Enter your Sign on user name and password.

Forgot password?
Sign In | Sign Up
Start learning today, and be successful in your academic & professional career. Start Today!

Use Chrome browser to play professor video
Raffi Hovasapian

Raffi Hovasapian

Example Problems with Acids, Bases & Buffers

Slide Duration:

Table of Contents

I. Preliminaries on Aqueous Chemistry
Aqueous Solutions & Concentration

39m 57s

Intro
0:00
Aqueous Solutions and Concentration
0:46
Definition of Solution
1:28
Example: Sugar Dissolved in Water
2:19
Example: Salt Dissolved in Water
3:04
A Solute Does Not Have to Be a Solid
3:37
A Solvent Does Not Have to Be a Liquid
5:02
Covalent Compounds
6:55
Ionic Compounds
7:39
Example: Table Sugar
9:12
Example: MgCl₂
10:40
Expressing Concentration: Molarity
13:42
Example 1
14:47
Example 1: Question
14:50
Example 1: Solution
15:40
Another Way to Express Concentration
22:01
Example 2
24:00
Example 2: Question
24:01
Example 2: Solution
24:49
Some Other Ways of Expressing Concentration
27:52
Example 3
29:30
Example 3: Question
29:31
Example 3: Solution
31:02
Dilution & Osmotic Pressure

38m 53s

Intro
0:00
Dilution
0:45
Definition of Dilution
0:46
Example 1: Question
2:08
Example 1: Basic Dilution Equation
4:20
Example 1: Solution
5:31
Example 2: Alternative Approach
12:05
Osmotic Pressure
14:34
Colligative Properties
15:02
Recall: Covalent Compounds and Soluble Ionic Compounds
17:24
Properties of Pure Water
19:42
Addition of a Solute
21:56
Osmotic Pressure: Conceptual Example
24:00
Equation for Osmotic Pressure
29:30
Example of 'i'
31:38
Example 3
32:50
More on Osmosis

29m 1s

Intro
0:00
More on Osmosis
1:25
Osmotic Pressure
1:26
Example 1: Molar Mass of Protein
5:25
Definition, Equation, and Unit of Osmolarity
13:13
Example 2: Osmolarity
15:19
Isotonic, Hypertonic, and Hypotonic
20:20
Example 3
22:20
More on Isotonic, Hypertonic, and Hypotonic
26:14
Osmosis vs. Osmotic Pressure
27:56
Acids & Bases

39m 11s

Intro
0:00
Acids and Bases
1:16
Let's Begin With H₂O
1:17
P-Scale
4:22
Example 1
6:39
pH
9:43
Strong Acids
11:10
Strong Bases
13:52
Weak Acids & Bases Overview
14:32
Weak Acids
15:49
Example 2: Phosphoric Acid
19:30
Weak Bases
24:50
Weak Base Produces Hydroxide Indirectly
25:41
Example 3: Pyridine
29:07
Acid Form and Base Form
32:02
Acid Reaction
35:50
Base Reaction
36:27
Ka, Kb, and Kw
37:14
Titrations and Buffers

41m 33s

Intro
0:00
Titrations
0:27
Weak Acid
0:28
Rearranging the Ka Equation
1:45
Henderson-Hasselbalch Equation
3:52
Fundamental Reaction of Acids and Bases
5:36
The Idea Behind a Titration
6:27
Let's Look at an Acetic Acid Solution
8:44
Titration Curve
17:00
Acetate
23:57
Buffers
26:57
Introduction to Buffers
26:58
What is a Buffer?
29:40
Titration Curve & Buffer Region
31:44
How a Buffer Works: Adding OH⁻
34:44
How a Buffer Works: Adding H⁺
35:58
Phosphate Buffer System
38:02
Example Problems with Acids, Bases & Buffers

44m 19s

Intro
0:00
Example 1
1:21
Example 1: Properties of Glycine
1:22
Example 1: Part A
3:40
Example 1: Part B
4:40
Example 2
9:02
Example 2: Question
9:03
Example 2: Total Phosphate Concentration
12:23
Example 2: Final Solution
17:10
Example 3
19:34
Example 3: Question
19:35
Example 3: pH Before
22:18
Example 3: pH After
24:24
Example 3: New pH
27:54
Example 4
30:00
Example 4: Question
30:01
Example 4: Equilibria
32:52
Example 4: 1st Reaction
38:04
Example 4: 2nd Reaction
39:53
Example 4: Final Solution
41:33
Hydrolysis & Condensation Reactions

18m 45s

Intro
0:00
Hydrolysis and Condensation Reactions
0:50
Hydrolysis
0:51
Condensation
2:42
Example 1: Hydrolysis of Ethyl Acetate
4:52
Example 2: Condensation of Acetic Acid with Ethanol
8:42
Example 3
11:18
Example 4: Formation & Hydrolysis of a Peptide Bond Between the Amino Acids Alanine & Serine
14:56
II. Amino Acids & Proteins: Primary Structure
Amino Acids

38m 19s

Intro
0:00
Amino Acids
0:17
Proteins & Amino Acids
0:18
Difference Between Amino Acids
4:20
α-Carbon
7:08
Configuration in Biochemistry
10:43
L-Glyceraldehyde & Fischer Projection
12:32
D-Glyceraldehyde & Fischer Projection
15:31
Amino Acids in Biological Proteins are the L Enantiomer
16:50
L-Amino Acid
18:04
L-Amino Acids Correspond to S-Enantiomers in the RS System
20:10
Classification of Amino Acids
22:53
Amino Acids With Non-Polar R Groups
26:45
Glycine
27:00
Alanine
27:48
Valine
28:15
Leucine
28:58
Proline
31:08
Isoleucine
32:42
Methionine
33:43
Amino Acids With Aromatic R Groups
34:33
Phenylalanine
35:26
Tyrosine
36:02
Tryptophan
36:32
Amino Acids, Continued

27m 14s

Intro
0:00
Amino Acids With Positively Charged R Groups
0:16
Lysine
0:52
Arginine
1:55
Histidine
3:15
Amino Acids With Negatively Charged R Groups
6:28
Aspartate
6:58
Glutamate
8:11
Amino Acids With Uncharged, but Polar R Groups
8:50
Serine
8:51
Threonine
10:21
Cysteine
11:06
Asparagine
11:35
Glutamine
12:44
More on Amino Acids
14:18
Cysteine Dimerizes to Form Cystine
14:53
Tryptophan, Tyrosine, and Phenylalanine
19:07
Other Amino Acids
20:53
Other Amino Acids: Hydroxy Lysine
22:34
Other Amino Acids: r-Carboxy Glutamate
25:37
Acid/Base Behavior of Amino Acids

48m 28s

Intro
0:00
Acid/Base Behavior of Amino Acids
0:27
Acid/Base Behavior of Amino Acids
0:28
Let's Look at Alanine
1:57
Titration of Acidic Solution of Alanine with a Strong Base
2:51
Amphoteric Amino Acids
13:24
Zwitterion & Isoelectric Point
16:42
Some Amino Acids Have 3 Ionizable Groups
20:35
Example: Aspartate
24:44
Example: Tyrosine
28:50
Rule of Thumb
33:04
Basis for the Rule
35:59
Example: Describe the Degree of Protonation for Each Ionizable Group
38:46
Histidine is Special
44:58
Peptides & Proteins

45m 18s

Intro
0:00
Peptides and Proteins
0:15
Introduction to Peptides and Proteins
0:16
Formation of a Peptide Bond: The Bond Between 2 Amino Acids
1:44
Equilibrium
7:53
Example 1: Build the Following Tripeptide Ala-Tyr-Ile
9:48
Example 1: Shape Structure
15:43
Example 1: Line Structure
17:11
Peptides Bonds
20:08
Terms We'll Be Using Interchangeably
23:14
Biological Activity & Size of a Peptide
24:58
Multi-Subunit Proteins
30:08
Proteins and Prosthetic Groups
32:13
Carbonic Anhydrase
37:35
Primary, Secondary, Tertiary, and Quaternary Structure of Proteins
40:26
Amino Acid Sequencing of a Peptide Chain

42m 47s

Intro
0:00
Amino Acid Sequencing of a Peptide Chain
0:30
Amino Acid Sequence and Its Structure
0:31
Edman Degradation: Overview
2:57
Edman Degradation: Reaction - Part 1
4:58
Edman Degradation: Reaction - Part 2
10:28
Edman Degradation: Reaction - Part 3
13:51
Mechanism Step 1: PTC (Phenylthiocarbamyl) Formation
19:01
Mechanism Step 2: Ring Formation & Peptide Bond Cleavage
23:03
Example: Write Out the Edman Degradation for the Tripeptide Ala-Tyr-Ser
30:29
Step 1
30:30
Step 2
34:21
Step 3
36:56
Step 4
38:28
Step 5
39:24
Step 6
40:44
Sequencing Larger Peptides & Proteins

1h 2m 33s

Intro
0:00
Sequencing Larger Peptides and Proteins
0:28
Identifying the N-Terminal Amino Acids With the Reagent Fluorodinitrobenzene (FDNB)
0:29
Sequencing Longer Peptides & Proteins Overview
5:54
Breaking Peptide Bond: Proteases and Chemicals
8:16
Some Enzymes/Chemicals Used for Fragmentation: Trypsin
11:14
Some Enzymes/Chemicals Used for Fragmentation: Chymotrypsin
13:02
Some Enzymes/Chemicals Used for Fragmentation: Cyanogen Bromide
13:28
Some Enzymes/Chemicals Used for Fragmentation: Pepsin
13:44
Cleavage Location
14:04
Example: Chymotrypsin
16:44
Example: Pepsin
18:17
More on Sequencing Larger Peptides and Proteins
19:29
Breaking Disulfide Bonds: Performic Acid
26:08
Breaking Disulfide Bonds: Dithiothreitol Followed by Iodoacetate
31:04
Example: Sequencing Larger Peptides and Proteins
37:03
Part 1 - Breaking Disulfide Bonds, Hydrolysis and Separation
37:04
Part 2 - N-Terminal Identification
44:16
Part 3 - Sequencing Using Pepsin
46:43
Part 4 - Sequencing Using Cyanogen Bromide
52:02
Part 5 - Final Sequence
56:48
Peptide Synthesis (Merrifield Process)

49m 12s

Intro
0:00
Peptide Synthesis (Merrifield Process)
0:31
Introduction to Synthesizing Peptides
0:32
Merrifield Peptide Synthesis: General Scheme
3:03
So What Do We Do?
6:07
Synthesis of Protein in the Body Vs. The Merrifield Process
7:40
Example: Synthesis of Ala-Gly-Ser
9:21
Synthesis of Ala-Gly-Ser: Reactions Overview
11:41
Synthesis of Ala-Gly-Ser: Reaction 1
19:34
Synthesis of Ala-Gly-Ser: Reaction 2
24:34
Synthesis of Ala-Gly-Ser: Reaction 3
27:34
Synthesis of Ala-Gly-Ser: Reaction 4 & 4a
28:48
Synthesis of Ala-Gly-Ser: Reaction 5
33:38
Synthesis of Ala-Gly-Ser: Reaction 6
36:45
Synthesis of Ala-Gly-Ser: Reaction 7 & 7a
37:44
Synthesis of Ala-Gly-Ser: Reaction 8
39:47
Synthesis of Ala-Gly-Ser: Reaction 9 & 10
43:23
Chromatography: Eluent, Stationary Phase, and Eluate
45:55
More Examples with Amino Acids & Peptides

54m 31s

Intro
0:00
Example 1
0:22
Data
0:23
Part A: What is the pI of Serine & Draw the Correct Structure
2:11
Part B: How Many mL of NaOH Solution Have Been Added at This Point (pI)?
5:27
Part C: At What pH is the Average Charge on Serine
10:50
Part D: Draw the Titration Curve for This Situation
14:50
Part E: The 10 mL of NaOH Added to the Solution at the pI is How Many Equivalents?
17:35
Part F: Serine Buffer Solution
20:22
Example 2
23:04
Data
23:05
Part A: Calculate the Minimum Molar Mass of the Protein
25:12
Part B: How Many Tyr Residues in this Protein?
28:34
Example 3
30:08
Question
30:09
Solution
34:30
Example 4
48:46
Question
48:47
Solution
49:50
III. Proteins: Secondary, Tertiary, and Quaternary Structure
Alpha Helix & Beta Conformation

50m 52s

Intro
0:00
Alpha Helix and Beta Conformation
0:28
Protein Structure Overview
0:29
Weak interactions Among the Amino Acid in the Peptide Chain
2:11
Two Principals of Folding Patterns
4:56
Peptide Bond
7:00
Peptide Bond: Resonance
9:46
Peptide Bond: φ Bond & ψ Bond
11:22
Secondary Structure
15:08
α-Helix Folding Pattern
17:28
Illustration 1: α-Helix Folding Pattern
19:22
Illustration 2: α-Helix Folding Pattern
21:39
β-Sheet
25:16
β-Conformation
26:04
Parallel & Anti-parallel
28:44
Parallel β-Conformation Arrangement of the Peptide Chain
30:12
Putting Together a Parallel Peptide Chain
35:16
Anti-Parallel β-Conformation Arrangement
37:42
Tertiary Structure
45:03
Quaternary Structure
45:52
Illustration 3: Myoglobin Tertiary Structure & Hemoglobin Quaternary Structure
47:13
Final Words on Alpha Helix and Beta Conformation
48:34
IV. Proteins: Function
Protein Function I: Ligand Binding & Myoglobin

51m 36s

Intro
0:00
Protein Function I: Ligand Binding & Myoglobin
0:30
Ligand
1:02
Binding Site
2:06
Proteins are Not Static or Fixed
3:36
Multi-Subunit Proteins
5:46
O₂ as a Ligand
7:21
Myoglobin, Protoporphyrin IX, Fe ²⁺, and O₂
12:54
Protoporphyrin Illustration
14:25
Myoglobin With a Heme Group Illustration
17:02
Fe²⁺ has 6 Coordination Sites & Binds O₂
18:10
Heme
19:44
Myoglobin Overview
22:40
Myoglobin and O₂ Interaction
23:34
Keq or Ka & The Measure of Protein's Affinity for Its Ligand
26:46
Defining α: Fraction of Binding Sites Occupied
32:52
Graph: α vs. [L]
37:33
For The Special Case of α = 0.5
39:01
Association Constant & Dissociation Constant
43:54
α & Kd
45:15
Myoglobin's Binding of O₂
48:20
Protein Function II: Hemoglobin

1h 3m 36s

Intro
0:00
Protein Function II: Hemoglobin
0:14
Hemoglobin Overview
0:15
Hemoglobin & Its 4 Subunits
1:22
α and β Interactions
5:18
Two Major Conformations of Hb: T State (Tense) & R State (Relaxed)
8:06
Transition From The T State to R State
12:03
Binding of Hemoglobins & O₂
14:02
Binding Curve
18:32
Hemoglobin in the Lung
27:28
Signoid Curve
30:13
Cooperative Binding
32:25
Hemoglobin is an Allosteric Protein
34:26
Homotropic Allostery
36:18
Describing Cooperative Binding Quantitatively
38:06
Deriving The Hill Equation
41:52
Graphing the Hill Equation
44:43
The Slope and Degree of Cooperation
46:25
The Hill Coefficient
49:48
Hill Coefficient = 1
51:08
Hill Coefficient < 1
55:55
Where the Graph Hits the x-axis
56:11
Graph for Hemoglobin
58:02
Protein Function III: More on Hemoglobin

1h 7m 16s

Intro
0:00
Protein Function III: More on Hemoglobin
0:11
Two Models for Cooperative Binding: MWC & Sequential Model
0:12
MWC Model
1:31
Hemoglobin Subunits
3:32
Sequential Model
8:00
Hemoglobin Transports H⁺ & CO₂
17:23
Binding Sites of H⁺ and CO₂
19:36
CO₂ is Converted to Bicarbonate
23:28
Production of H⁺ & CO₂ in Tissues
27:28
H⁺ & CO₂ Binding are Inversely Related to O₂ Binding
28:31
The H⁺ Bohr Effect: His¹⁴⁶ Residue on the β Subunits
33:31
Heterotropic Allosteric Regulation of O₂ Binding by 2,3-Biphosphoglycerate (2,3 BPG)
39:53
Binding Curve for 2,3 BPG
56:21
V. Enzymes
Enzymes I

41m 38s

Intro
0:00
Enzymes I
0:38
Enzymes Overview
0:39
Cofactor
4:38
Holoenzyme
5:52
Apoenzyme
6:40
Riboflavin, FAD, Pyridoxine, Pyridoxal Phosphate Structures
7:28
Carbonic Anhydrase
8:45
Classification of Enzymes
9:55
Example: EC 1.1.1.1
13:04
Reaction of Oxidoreductases
16:23
Enzymes: Catalysts, Active Site, and Substrate
18:28
Illustration of Enzymes, Substrate, and Active Site
27:22
Catalysts & Activation Energies
29:57
Intermediates
36:00
Enzymes II

44m 2s

Intro
0:00
Enzymes II: Transitions State, Binding Energy, & Induced Fit
0:18
Enzymes 'Fitting' Well With The Transition State
0:20
Example Reaction: Breaking of a Stick
3:40
Another Energy Diagram
8:20
Binding Energy
9:48
Enzymes Specificity
11:03
Key Point: Optimal Interactions Between Substrate & Enzymes
15:15
Induced Fit
16:25
Illustrations: Induced Fit
20:58
Enzymes II: Catalytic Mechanisms
22:17
General Acid/Base Catalysis
23:56
Acid Form & Base Form of Amino Acid: Glu &Asp
25:26
Acid Form & Base Form of Amino Acid: Lys & Arg
26:30
Acid Form & Base Form of Amino Acid: Cys
26:51
Acid Form & Base Form of Amino Acid: His
27:30
Acid Form & Base Form of Amino Acid: Ser
28:16
Acid Form & Base Form of Amino Acid: Tyr
28:30
Example: Phosphohexose Isomerase
29:20
Covalent Catalysis
34:19
Example: Glyceraldehyde 3-Phosphate Dehydrogenase
35:34
Metal Ion Catalysis: Isocitrate Dehydrogenase
38:45
Function of Mn²⁺
42:15
Enzymes III: Kinetics

56m 40s

Intro
0:00
Enzymes III: Kinetics
1:40
Rate of an Enzyme-Catalyzed Reaction & Substrate Concentration
1:41
Graph: Substrate Concentration vs. Reaction Rate
10:43
Rate At Low and High Substrate Concentration
14:26
Michaelis & Menten Kinetics
20:16
More On Rate & Concentration of Substrate
22:46
Steady-State Assumption
26:02
Rate is Determined by How Fast ES Breaks Down to Product
31:36
Total Enzyme Concentration: [Et] = [E] + [ES]
35:35
Rate of ES Formation
36:44
Rate of ES Breakdown
38:40
Measuring Concentration of Enzyme-Substrate Complex
41:19
Measuring Initial & Maximum Velocity
43:43
Michaelis & Menten Equation
46:44
What Happens When V₀ = (1/2) Vmax?
49:12
When [S] << Km
53:32
When [S] >> Km
54:44
Enzymes IV: Lineweaver-Burk Plots

20m 37s

Intro
0:00
Enzymes IV: Lineweaver-Burk Plots
0:45
Deriving The Lineweaver-Burk Equation
0:46
Lineweaver-Burk Plots
3:55
Example 1: Carboxypeptidase A
8:00
More on Km, Vmax, and Enzyme-catalyzed Reaction
15:54
Enzymes V: Enzyme Inhibition

51m 37s

Intro
0:00
Enzymes V: Enzyme Inhibition Overview
0:42
Enzyme Inhibitors Overview
0:43
Classes of Inhibitors
2:32
Competitive Inhibition
3:08
Competitive Inhibition
3:09
Michaelis & Menten Equation in the Presence of a Competitive Inhibitor
7:40
Double-Reciprocal Version of the Michaelis & Menten Equation
14:48
Competitive Inhibition Graph
16:37
Uncompetitive Inhibition
19:23
Uncompetitive Inhibitor
19:24
Michaelis & Menten Equation for Uncompetitive Inhibition
22:10
The Lineweaver-Burk Equation for Uncompetitive Inhibition
26:04
Uncompetitive Inhibition Graph
27:42
Mixed Inhibition
30:30
Mixed Inhibitor
30:31
Double-Reciprocal Version of the Equation
33:34
The Lineweaver-Burk Plots for Mixed Inhibition
35:02
Summary of Reversible Inhibitor Behavior
38:00
Summary of Reversible Inhibitor Behavior
38:01
Note: Non-Competitive Inhibition
42:22
Irreversible Inhibition
45:15
Irreversible Inhibition
45:16
Penicillin & Transpeptidase Enzyme
46:50
Enzymes VI: Regulatory Enzymes

51m 23s

Intro
0:00
Enzymes VI: Regulatory Enzymes
0:45
Regulatory Enzymes Overview
0:46
Example: Glycolysis
2:27
Allosteric Regulatory Enzyme
9:19
Covalent Modification
13:08
Two Other Regulatory Processes
16:28
Allosteric Regulation
20:58
Feedback Inhibition
25:12
Feedback Inhibition Example: L-Threonine → L-Isoleucine
26:03
Covalent Modification
27:26
Covalent Modulators: -PO₃²⁻
29:30
Protein Kinases
31:59
Protein Phosphatases
32:47
Addition/Removal of -PO₃²⁻ and the Effect on Regulatory Enzyme
33:36
Phosphorylation Sites of a Regulatory Enzyme
38:38
Proteolytic Cleavage
41:48
Zymogens: Chymotrypsin & Trypsin
43:58
Enzymes That Use More Than One Regulatory Process: Bacterial Glutamine Synthetase
48:59
Why The Complexity?
50:27
Enzymes VII: Km & Kcat

54m 49s

Intro
0:00
Km
1:48
Recall the Michaelis–Menten Equation
1:49
Km & Enzyme's Affinity
6:18
Rate Forward, Rate Backward, and Equilibrium Constant
11:08
When an Enzyme's Affinity for Its Substrate is High
14:17
More on Km & Enzyme Affinity
17:29
The Measure of Km Under Michaelis–Menten kinetic
23:19
Kcat (First-order Rate Constant or Catalytic Rate Constant)
24:10
Kcat: Definition
24:11
Kcat & The Michaelis–Menten Postulate
25:18
Finding Vmax and [Et}
27:27
Units for Vmax and Kcat
28:26
Kcat: Turnover Number
28:55
Michaelis–Menten Equation
32:12
Km & Kcat
36:37
Second Order Rate Equation
36:38
(Kcat)/(Km): Overview
39:22
High (Kcat)/(Km)
40:20
Low (Kcat)/(Km)
43:16
Practical Big Picture
46:28
Upper Limit to (Kcat)/(Km)
48:56
More On Kcat and Km
49:26
VI. Carbohydrates
Monosaccharides

1h 17m 46s

Intro
0:00
Monosaccharides
1:49
Carbohydrates Overview
1:50
Three Major Classes of Carbohydrates
4:48
Definition of Monosaccharides
5:46
Examples of Monosaccharides: Aldoses
7:06
D-Glyceraldehyde
7:39
D-Erythrose
9:00
D-Ribose
10:10
D-Glucose
11:20
Observation: Aldehyde Group
11:54
Observation: Carbonyl 'C'
12:30
Observation: D & L Naming System
12:54
Examples of Monosaccharides: Ketose
16:54
Dihydroxy Acetone
17:28
D-Erythrulose
18:30
D-Ribulose
19:49
D-Fructose
21:10
D-Glucose Comparison
23:18
More information of Ketoses
24:50
Let's Look Closer at D-Glucoses
25:50
Let's Look At All the D-Hexose Stereoisomers
31:22
D-Allose
32:20
D-Altrose
33:01
D-Glucose
33:39
D-Gulose
35:00
D-Mannose
35:40
D-Idose
36:42
D-Galactose
37:14
D-Talose
37:42
Epimer
40:05
Definition of Epimer
40:06
Example of Epimer: D-Glucose, D-Mannose, and D-Galactose
40:57
Hemiacetal or Hemiketal
44:36
Hemiacetal/Hemiketal Overview
45:00
Ring Formation of the α and β Configurations of D-Glucose
50:52
Ring Formation of the α and β Configurations of Fructose
1:01:39
Haworth Projection
1:07:34
Pyranose & Furanose Overview
1:07:38
Haworth Projection: Pyranoses
1:09:30
Haworth Projection: Furanose
1:14:56
Hexose Derivatives & Reducing Sugars

37m 6s

Intro
0:00
Hexose Derivatives
0:15
Point of Clarification: Forming a Cyclic Sugar From a Linear Sugar
0:16
Let's Recall the α and β Anomers of Glucose
8:42
α-Glucose
10:54
Hexose Derivatives that Play Key Roles in Physiology Progression
17:38
β-Glucose
18:24
β-Glucosamine
18:48
N-Acetyl-β-Glucosamine
20:14
β-Glucose-6-Phosphate
22:22
D-Gluconate
24:10
Glucono-δ-Lactone
26:33
Reducing Sugars
29:50
Reducing Sugars Overview
29:51
Reducing Sugars Example: β-Galactose
32:36
Disaccharides

43m 32s

Intro
0:00
Disaccharides
0:15
Disaccharides Overview
0:19
Examples of Disaccharides & How to Name Them
2:49
Disaccharides Trehalose Overview
15:46
Disaccharides Trehalose: Flip
20:52
Disaccharides Trehalose: Spin
28:36
Example: Draw the Structure
33:12
Polysaccharides

39m 25s

Intro
0:00
Recap Example: Draw the Structure of Gal(α1↔β1)Man
0:38
Polysaccharides
9:46
Polysaccharides Overview
9:50
Homopolysaccharide
13:12
Heteropolysaccharide
13:47
Homopolysaccharide as Fuel Storage
16:23
Starch Has Two Types of Glucose Polymer: Amylose
17:10
Starch Has Two Types of Glucose Polymer: Amylopectin
18:04
Polysaccharides: Reducing End & Non-Reducing End
19:30
Glycogen
20:06
Examples: Structures of Polysaccharides
21:42
Let's Draw an (α1→4) & (α1→6) of Amylopectin by Hand.
28:14
More on Glycogen
31:17
Glycogen, Concentration, & The Concept of Osmolarity
35:16
Polysaccharides, Part 2

44m 15s

Intro
0:00
Polysaccharides
0:17
Example: Cellulose
0:34
Glycoside Bond
7:25
Example Illustrations
12:30
Glycosaminoglycans Part 1
15:55
Glycosaminoglycans Part 2
18:34
Glycosaminoglycans & Sulfate Attachments
22:42
β-D-N-Acetylglucosamine
24:49
β-D-N-AcetylGalactosamine
25:42
β-D-Glucuronate
26:44
β-L-Iduronate
27:54
More on Sulfate Attachments
29:49
Hylarunic Acid
32:00
Hyaluronates
39:32
Other Glycosaminoglycans
40:46
Glycoconjugates

44m 23s

Intro
0:00
Glycoconjugates
0:24
Overview
0:25
Proteoglycan
2:53
Glycoprotein
5:20
Glycolipid
7:25
Proteoglycan vs. Glycoprotein
8:15
Cell Surface Diagram
11:17
Proteoglycan Common Structure
14:24
Example: Chondroitin-4-Sulfate
15:06
Glycoproteins
19:50
The Monomers that Commonly Show Up in The Oligo Portions of Glycoproteins
28:02
N-Acetylneuraminic Acid
31:17
L-Furose
32:37
Example of an N-Linked Oligosaccharide
33:21
Cell Membrane Structure
36:35
Glycolipids & Lipopolysaccharide
37:22
Structure Example
41:28
More Example Problems with Carbohydrates

40m 22s

Intro
0:00
Example 1
1:09
Example 2
2:34
Example 3
5:12
Example 4
16:19
Question
16:20
Solution
17:25
Example 5
24:18
Question
24:19
Structure of 2,3-Di-O-Methylglucose
26:47
Part A
28:11
Part B
33:46
VII. Lipids
Fatty Acids & Triacylglycerols

54m 55s

Intro
0:00
Fatty Acids
0:32
Lipids Overview
0:34
Introduction to Fatty Acid
3:18
Saturated Fatty Acid
6:13
Unsaturated or Polyunsaturated Fatty Acid
7:07
Saturated Fatty Acid Example
7:46
Unsaturated Fatty Acid Example
9:06
Notation Example: Chain Length, Degree of Unsaturation, & Double Bonds Location of Fatty Acid
11:56
Example 1: Draw the Structure
16:18
Example 2: Give the Shorthand for cis,cis-5,8-Hexadecadienoic Acid
20:12
Example 3
23:12
Solubility of Fatty Acids
25:45
Melting Points of Fatty Acids
29:40
Triacylglycerols
34:13
Definition of Triacylglycerols
34:14
Structure of Triacylglycerols
35:08
Example: Triacylglycerols
40:23
Recall Ester Formation
43:57
The Body's Primary Fuel-Reserves
47:22
Two Primary Advantages to Storing Energy as Triacylglycerols Instead of Glycogen: Number 1
49:24
Two Primary Advantages to Storing Energy as Triacylglycerols Instead of Glycogen: Number 2
51:54
Membrane Lipids

38m 51s

Intro
0:00
Membrane Lipids
0:26
Definition of Membrane Lipids
0:27
Five Major Classes of Membrane Lipids
2:38
Glycerophospholipids
5:04
Glycerophospholipids Overview
5:05
The X Group
8:05
Example: Phosphatidyl Ethanolamine
10:51
Example: Phosphatidyl Choline
13:34
Phosphatidyl Serine
15:16
Head Groups
16:50
Ether Linkages Instead of Ester Linkages
20:05
Galactolipids
23:39
Galactolipids Overview
23:40
Monogalactosyldiacylglycerol: MGDG
25:17
Digalactosyldiacylglycerol: DGDG
28:13
Structure Examples 1: Lipid Bilayer
31:35
Structure Examples 2: Cross Section of a Cell
34:56
Structure Examples 3: MGDG & DGDG
36:28
Membrane Lipids, Part 2

38m 20s

Intro
0:00
Sphingolipids
0:11
Sphingolipid Overview
0:12
Sphingosine Structure
1:42
Ceramide
3:56
Subclasses of Sphingolipids Overview
6:00
Subclasses of Sphingolipids: Sphingomyelins
7:53
Sphingomyelins
7:54
Subclasses of Sphingolipids: Glycosphingolipid
12:47
Glycosphingolipid Overview
12:48
Cerebrosides & Globosides Overview
14:33
Example: Cerebrosides
15:43
Example: Globosides
17:14
Subclasses of Sphingolipids: Gangliosides
19:07
Gangliosides
19:08
Medical Application: Tay-Sachs Disease
23:34
Sterols
30:45
Sterols: Basic Structure
30:46
Important Example: Cholesterol
32:01
Structures Example
34:13
The Biologically Active Lipids

48m 36s

Intro
0:00
The Biologically Active Lipids
0:44
Phosphatidyl Inositol Structure
0:45
Phosphatidyl Inositol Reaction
3:24
Image Example
12:49
Eicosanoids
14:12
Arachidonic Acid & Membrane Lipid Containing Arachidonic Acid
18:41
Three Classes of Eicosanoids
20:42
Overall Structures
21:38
Prostagladins
22:56
Thromboxane
27:19
Leukotrienes
30:19
More On The Biologically Active Lipids
33:34
Steroid Hormones
33:35
Fat Soluble Vitamins
38:25
Vitamin D₃
40:40
Vitamin A
43:17
Vitamin E
45:12
Vitamin K
47:17
VIII. Energy & Biological Systems (Bioenergetics)
Thermodynamics, Free Energy & Equilibrium

45m 51s

Intro
0:00
Thermodynamics, Free Energy and Equilibrium
1:03
Reaction: Glucose + Pi → Glucose 6-Phosphate
1:50
Thermodynamics & Spontaneous Processes
3:31
In Going From Reactants → Product, a Reaction Wants to Release Heat
6:30
A Reaction Wants to Become More Disordered
9:10
∆H < 0
10:30
∆H > 0
10:57
∆S > 0
11:23
∆S <0
11:56
∆G = ∆H - T∆S at Constant Pressure
12:15
Gibbs Free Energy
15:00
∆G < 0
16:49
∆G > 0
17:07
Reference Frame For Thermodynamics Measurements
17:57
More On BioChemistry Standard
22:36
Spontaneity
25:36
Keq
31:45
Example: Glucose + Pi → Glucose 6-Phosphate
34:14
Example Problem 1
40:25
Question
40:26
Solution
41:12
More on Thermodynamics & Free Energy

37m 6s

Intro
0:00
More on Thermodynamics & Free Energy
0:16
Calculating ∆G Under Standard Conditions
0:17
Calculating ∆G Under Physiological Conditions
2:05
∆G < 0
5:39
∆G = 0
7:03
Reaction Moving Forward Spontaneously
8:00
∆G & The Maximum Theoretical Amount of Free Energy Available
10:36
Example Problem 1
13:11
Reactions That Have Species in Common
17:48
Example Problem 2: Part 1
20:10
Example Problem 2: Part 2- Enzyme Hexokinase & Coupling
25:08
Example Problem 2: Part 3
30:34
Recap
34:45
ATP & Other High-Energy Compounds

44m 32s

Intro
0:00
ATP & Other High-Energy Compounds
0:10
Endergonic Reaction Coupled With Exergonic Reaction
0:11
Major Theme In Metabolism
6:56
Why the ∆G°' for ATP Hydrolysis is Large & Negative
12:24
∆G°' for ATP Hydrolysis
12:25
Reason 1: Electrostatic Repulsion
14:24
Reason 2: Pi & Resonance Forms
15:33
Reason 3: Concentrations of ADP & Pi
17:32
ATP & Other High-Energy Compounds Cont'd
18:48
More On ∆G°' & Hydrolysis
18:49
Other Compounds That Have Large Negative ∆G°' of Hydrolysis: Phosphoenol Pyruvate (PEP)
25:14
Enzyme Pyruvate Kinase
30:36
Another High Energy Molecule: 1,3 Biphosphoglycerate
36:17
Another High Energy Molecule: Phophocreatine
39:41
Phosphoryl Group Transfers

30m 8s

Intro
0:00
Phosphoryl Group Transfer
0:27
Phosphoryl Group Transfer Overview
0:28
Example: Glutamate → Glutamine Part 1
7:11
Example: Glutamate → Glutamine Part 2
13:29
ATP Not Only Transfers Phosphoryl, But Also Pyrophosphoryl & Adenylyl Groups
17:03
Attack At The γ Phosphorous Transfers a Phosphoryl
19:02
Attack At The β Phosphorous Gives Pyrophosphoryl
22:44
Oxidation-Reduction Reactions

49m 46s

Intro
0:00
Oxidation-Reduction Reactions
1:32
Redox Reactions
1:33
Example 1: Mg + Al³⁺ → Mg²⁺ + Al
3:49
Reduction Potential Definition
10:47
Reduction Potential Example
13:38
Organic Example
22:23
Review: How To Find The Oxidation States For Carbon
24:15
Examples: Oxidation States For Carbon
27:45
Example 1: Oxidation States For Carbon
27:46
Example 2: Oxidation States For Carbon
28:36
Example 3: Oxidation States For Carbon
29:18
Example 4: Oxidation States For Carbon
29:44
Example 5: Oxidation States For Carbon
30:10
Example 6: Oxidation States For Carbon
30:40
Example 7: Oxidation States For Carbon
31:20
Example 8: Oxidation States For Carbon
32:10
Example 9: Oxidation States For Carbon
32:52
Oxidation-Reduction Reactions, cont'd
35:22
More On Reduction Potential
35:28
Lets' Start With ∆G = ∆G°' + RTlnQ
38:29
Example: Oxidation Reduction Reactions
41:42
More On Oxidation-Reduction Reactions

56m 34s

Intro
0:00
More On Oxidation-Reduction Reactions
0:10
Example 1: What If the Concentrations Are Not Standard?
0:11
Alternate Procedure That Uses The 1/2 Reactions Individually
8:57
Universal Electron Carriers in Aqueous Medium: NAD+ & NADH
15:12
The Others Are…
19:22
NAD+ & NADP Coenzymes
20:56
FMN & FAD
22:03
Nicotinamide Adenine Dinucleotide (Phosphate)
23:03
Reduction 1/2 Reactions
36:10
Ratio of NAD+ : NADH
36:52
Ratio of NADPH : NADP+
38:02
Specialized Roles of NAD+ & NADPH
38:48
Oxidoreductase Enzyme Overview
40:26
Examples of Oxidoreductase
43:32
The Flavin Nucleotides
46:46
Example Problems For Bioenergetics

42m 12s

Intro
0:00
Example 1: Calculate the ∆G°' For The Following Reaction
1:04
Example 1: Question
1:05
Example 1: Solution
2:20
Example 2: Calculate the Keq For the Following
4:20
Example 2: Question
4:21
Example 2: Solution
5:54
Example 3: Calculate the ∆G°' For The Hydrolysis of ATP At 25°C
8:52
Example 3: Question
8:53
Example 3: Solution
10:30
Example 3: Alternate Procedure
13:48
Example 4: Problems For Bioenergetics
16:46
Example 4: Questions
16:47
Example 4: Part A Solution
21:19
Example 4: Part B Solution
23:26
Example 4: Part C Solution
26:12
Example 5: Problems For Bioenergetics
29:27
Example 5: Questions
29:35
Example 5: Solution - Part 1
32:16
Example 5: Solution - Part 2
34:39
IX. Glycolysis and Gluconeogenesis
Overview of Glycolysis I

43m 32s

Intro
0:00
Overview of Glycolysis
0:48
Three Primary Paths For Glucose
1:04
Preparatory Phase of Glycolysis
4:40
Payoff Phase of Glycolysis
6:40
Glycolysis Reactions Diagram
7:58
Enzymes of Glycolysis
12:41
Glycolysis Reactions
16:02
Step 1
16:03
Step 2
18:03
Step 3
18:52
Step 4
20:08
Step 5
21:42
Step 6
22:44
Step 7
24:22
Step 8
25:11
Step 9
26:00
Step 10
26:51
Overview of Glycolysis Cont.
27:28
The Overall Reaction for Glycolysis
27:29
Recall The High-Energy Phosphorylated Compounds Discusses In The Bioenergetics Unit
33:10
What Happens To The Pyruvate That Is Formed?
37:58
Glycolysis II

1h 1m 47s

Intro
0:00
Glycolysis Step 1: The Phosphorylation of Glucose
0:27
Glycolysis Step 1: Reaction
0:28
Hexokinase
2:28
Glycolysis Step 1: Mechanism-Simple Nucleophilic Substitution
6:34
Glycolysis Step 2: Conversion of Glucose 6-Phosphate → Fructose 6-Phosphate
11:33
Glycolysis Step 2: Reaction
11:34
Glycolysis Step 2: Mechanism, Part 1
14:40
Glycolysis Step 2: Mechanism, Part 2
18:16
Glycolysis Step 2: Mechanism, Part 3
19:56
Glycolysis Step 2: Mechanism, Part 4 (Ring Closing & Dissociation)
21:54
Glycolysis Step 3: Conversion of Fructose 6-Phosphate to Fructose 1,6-Biphosphate
24:16
Glycolysis Step 3: Reaction
24:17
Glycolysis Step 3: Mechanism
26:40
Glycolysis Step 4: Cleavage of Fructose 1,6-Biphosphate
31:10
Glycolysis Step 4: Reaction
31:11
Glycolysis Step 4: Mechanism, Part 1 (Binding & Ring Opening)
35:26
Glycolysis Step 4: Mechanism, Part 2
37:40
Glycolysis Step 4: Mechanism, Part 3
39:30
Glycolysis Step 4: Mechanism, Part 4
44:00
Glycolysis Step 4: Mechanism, Part 5
46:34
Glycolysis Step 4: Mechanism, Part 6
49:00
Glycolysis Step 4: Mechanism, Part 7
50:12
Hydrolysis of The Imine
52:33
Glycolysis Step 5: Conversion of Dihydroxyaceton Phosphate to Glyceraldehyde 3-Phosphate
55:38
Glycolysis Step 5: Reaction
55:39
Breakdown and Numbering of Sugar
57:40
Glycolysis III

59m 17s

Intro
0:00
Glycolysis Step 5: Conversion of Dihydroxyaceton Phosphate to Glyceraldehyde 3-Phosphate
0:44
Glycolysis Step 5: Mechanism, Part 1
0:45
Glycolysis Step 5: Mechanism, Part 2
3:53
Glycolysis Step 6: Oxidation of Glyceraldehyde 3-Phosphate to 1,3-Biphosphoglycerate
5:14
Glycolysis Step 6: Reaction
5:15
Glycolysis Step 6: Mechanism, Part 1
8:52
Glycolysis Step 6: Mechanism, Part 2
12:58
Glycolysis Step 6: Mechanism, Part 3
14:26
Glycolysis Step 6: Mechanism, Part 4
16:23
Glycolysis Step 7: Phosphoryl Transfer From 1,3-Biphosphoglycerate to ADP to Form ATP
19:08
Glycolysis Step 7: Reaction
19:09
Substrate-Level Phosphorylation
23:18
Glycolysis Step 7: Mechanism (Nucleophilic Substitution)
26:57
Glycolysis Step 8: Conversion of 3-Phosphoglycerate to 2-Phosphoglycerate
28:44
Glycolysis Step 8: Reaction
28:45
Glycolysis Step 8: Mechanism, Part 1
30:08
Glycolysis Step 8: Mechanism, Part 2
32:24
Glycolysis Step 8: Mechanism, Part 3
34:02
Catalytic Cycle
35:42
Glycolysis Step 9: Dehydration of 2-Phosphoglycerate to Phosphoenol Pyruvate
37:20
Glycolysis Step 9: Reaction
37:21
Glycolysis Step 9: Mechanism, Part 1
40:12
Glycolysis Step 9: Mechanism, Part 2
42:01
Glycolysis Step 9: Mechanism, Part 3
43:58
Glycolysis Step 10: Transfer of a Phosphoryl Group From Phosphoenol Pyruvate To ADP To Form ATP
45:16
Glycolysis Step 10: Reaction
45:17
Substrate-Level Phosphorylation
48:32
Energy Coupling Reaction
51:24
Glycolysis Balance Sheet
54:15
Glycolysis Balance Sheet
54:16
What Happens to The 6 Carbons of Glucose?
56:22
What Happens to 2 ADP & 2 Pi?
57:04
What Happens to The 4e⁻ ?
57:15
Glycolysis IV

39m 47s

Intro
0:00
Feeder Pathways
0:42
Feeder Pathways Overview
0:43
Starch, Glycogen
2:25
Lactose
4:38
Galactose
4:58
Manose
5:22
Trehalose
5:45
Sucrose
5:56
Fructose
6:07
Fates of Pyruvate: Aerobic & Anaerobic Conditions
7:39
Aerobic Conditions & Pyruvate
7:40
Anaerobic Fates of Pyruvate
11:18
Fates of Pyruvate: Lactate Acid Fermentation
14:10
Lactate Acid Fermentation
14:11
Fates of Pyruvate: Ethanol Fermentation
19:01
Ethanol Fermentation Reaction
19:02
TPP: Thiamine Pyrophosphate (Functions and Structure)
23:10
Ethanol Fermentation Mechanism, Part 1
27:53
Ethanol Fermentation Mechanism, Part 2
29:06
Ethanol Fermentation Mechanism, Part 3
31:15
Ethanol Fermentation Mechanism, Part 4
32:44
Ethanol Fermentation Mechanism, Part 5
34:33
Ethanol Fermentation Mechanism, Part 6
35:48
Gluconeogenesis I

41m 34s

Intro
0:00
Gluconeogenesis, Part 1
1:02
Gluconeogenesis Overview
1:03
3 Glycolytic Reactions That Are Irreversible Under Physiological Conditions
2:29
Gluconeogenesis Reactions Overview
6:17
Reaction: Pyruvate to Oxaloacetate
11:07
Reaction: Oxaloacetate to Phosphoenolpyruvate (PEP)
13:29
First Pathway That Pyruvate Can Take to Become Phosphoenolpyruvate
15:24
Second Pathway That Pyruvate Can Take to Become Phosphoenolpyruvate
21:00
Transportation of Pyruvate From The Cytosol to The Mitochondria
24:15
Transportation Mechanism, Part 1
26:41
Transportation Mechanism, Part 2
30:43
Transportation Mechanism, Part 3
34:04
Transportation Mechanism, Part 4
38:14
Gluconeogenesis II

34m 18s

Intro
0:00
Oxaloacetate → Phosphoenolpyruvate (PEP)
0:35
Mitochondrial Membrane Does Not Have a Transporter for Oxaloactate
0:36
Reaction: Oxaloacetate to Phosphoenolpyruvate (PEP)
3:36
Mechanism: Oxaloacetate to Phosphoenolpyruvate (PEP)
4:48
Overall Reaction: Pyruvate to Phosphoenolpyruvate
7:01
Recall The Two Pathways That Pyruvate Can Take to Become Phosphoenolpyruvate
10:16
NADH in Gluconeogenesis
12:29
Second Pathway: Lactate → Pyruvate
18:22
Cytosolic PEP Carboxykinase, Mitochondrial PEP Carboxykinase, & Isozymes
18:23
2nd Bypass Reaction
23:04
3rd Bypass Reaction
24:01
Overall Process
25:17
Other Feeder Pathways For Gluconeogenesis
26:35
Carbon Intermediates of The Citric Acid Cycle
26:36
Amino Acids & The Gluconeogenic Pathway
29:45
Glycolysis & Gluconeogenesis Are Reciprocally Regulated
32:00
The Pentose Phosphate Pathway

42m 52s

Intro
0:00
The Pentose Phosphate Pathway Overview
0:17
The Major Fate of Glucose-6-Phosphate
0:18
The Pentose Phosphate Pathway (PPP) Overview
1:00
Oxidative Phase of The Pentose Phosphate Pathway
4:33
Oxidative Phase of The Pentose Phosphate Pathway: Reaction Overview
4:34
Ribose-5-Phosphate: Glutathione & Reductive Biosynthesis
9:02
Glucose-6-Phosphate to 6-Phosphogluconate
12:48
6-Phosphogluconate to Ribulose-5-Phosphate
15:39
Ribulose-5-Phosphate to Ribose-5-Phosphate
17:05
Non-Oxidative Phase of The Pentose Phosphate Pathway
19:55
Non-Oxidative Phase of The Pentose Phosphate Pathway: Overview
19:56
General Transketolase Reaction
29:03
Transaldolase Reaction
35:10
Final Transketolase Reaction
39:10
X. The Citric Acid Cycle (Krebs Cycle)
Citric Acid Cycle I

36m 10s

Intro
0:00
Stages of Cellular Respiration
0:23
Stages of Cellular Respiration
0:24
From Pyruvate to Acetyl-CoA
6:56
From Pyruvate to Acetyl-CoA: Pyruvate Dehydrogenase Complex
6:57
Overall Reaction
8:42
Oxidative Decarboxylation
11:54
Pyruvate Dehydrogenase (PDH) & Enzymes
15:30
Pyruvate Dehydrogenase (PDH) Requires 5 Coenzymes
17:15
Molecule of CoEnzyme A
18:52
Thioesters
20:56
Lipoic Acid
22:31
Lipoate Is Attached To a Lysine Residue On E₂
24:42
Pyruvate Dehydrogenase Complex: Reactions
26:36
E1: Reaction 1 & 2
30:38
E2: Reaction 3
31:58
E3: Reaction 4 & 5
32:44
Substrate Channeling
34:17
Citric Acid Cycle II

49m 20s

Intro
0:00
Citric Acid Cycle Reactions Overview
0:26
Citric Acid Cycle Reactions Overview: Part 1
0:27
Citric Acid Cycle Reactions Overview: Part 2
7:03
Things to Note
10:58
Citric Acid Cycle Reactions & Mechanism
13:57
Reaction 1: Formation of Citrate
13:58
Reaction 1: Mechanism
19:01
Reaction 2: Citrate to Cis Aconistate to Isocitrate
28:50
Reaction 3: Isocitrate to α-Ketoglutarate
32:35
Reaction 3: Two Isocitrate Dehydrogenase Enzymes
36:24
Reaction 3: Mechanism
37:33
Reaction 4: Oxidation of α-Ketoglutarate to Succinyl-CoA
41:38
Reaction 4: Notes
46:34
Citric Acid Cycle III

44m 11s

Intro
0:00
Citric Acid Cycle Reactions & Mechanism
0:21
Reaction 5: Succinyl-CoA to Succinate
0:24
Reaction 5: Reaction Sequence
2:35
Reaction 6: Oxidation of Succinate to Fumarate
8:28
Reaction 7: Fumarate to Malate
10:17
Reaction 8: Oxidation of L-Malate to Oxaloacetate
14:15
More On The Citric Acid Cycle
17:17
Energy from Oxidation
17:18
How Can We Transfer This NADH Into the Mitochondria
27:10
Citric Cycle is Amphibolic - Works In Both Anabolic & Catabolic Pathways
32:06
Biosynthetic Processes
34:29
Anaplerotic Reactions Overview
37:26
Anaplerotic: Reaction 1
41:42
XI. Catabolism of Fatty Acids
Fatty Acid Catabolism I

48m 11s

Intro
0:00
Introduction to Fatty Acid Catabolism
0:21
Introduction to Fatty Acid Catabolism
0:22
Vertebrate Cells Obtain Fatty Acids for Catabolism From 3 Sources
2:16
Diet: Part 1
4:00
Diet: Part 2
5:35
Diet: Part 3
6:20
Diet: Part 4
6:47
Diet: Part 5
10:18
Diet: Part 6
10:54
Diet: Part 7
12:04
Diet: Part 8
12:26
Fats Stored in Adipocytes Overview
13:54
Fats Stored in Adipocytes (Fat Cells): Part 1
16:13
Fats Stored in Adipocytes (Fat Cells): Part 2
17:16
Fats Stored in Adipocytes (Fat Cells): Part 3
19:42
Fats Stored in Adipocytes (Fat Cells): Part 4
20:52
Fats Stored in Adipocytes (Fat Cells): Part 5
22:56
Mobilization of TAGs Stored in Fat Cells
24:35
Fatty Acid Oxidation
28:29
Fatty Acid Oxidation
28:48
3 Reactions of the Carnitine Shuttle
30:42
Carnitine Shuttle & The Mitochondrial Matrix
36:25
CAT I
43:58
Carnitine Shuttle is the Rate-Limiting Steps
46:24
Fatty Acid Catabolism II

45m 58s

Intro
0:00
Fatty Acid Catabolism
0:15
Fatty Acid Oxidation Takes Place in 3 Stages
0:16
β-Oxidation
2:05
β-Oxidation Overview
2:06
Reaction 1
4:20
Reaction 2
7:35
Reaction 3
8:52
Reaction 4
10:16
β-Oxidation Reactions Discussion
11:34
Notes On β-Oxidation
15:14
Double Bond After The First Reaction
15:15
Reaction 1 is Catalyzed by 3 Isozymes of Acyl-CoA Dehydrogenase
16:04
Reaction 2 & The Addition of H₂O
18:38
After Reaction 4
19:24
Production of ATP
20:04
β-Oxidation of Unsaturated Fatty Acid
21:25
β-Oxidation of Unsaturated Fatty Acid
22:36
β-Oxidation of Mono-Unsaturates
24:49
β-Oxidation of Mono-Unsaturates: Reaction 1
24:50
β-Oxidation of Mono-Unsaturates: Reaction 2
28:43
β-Oxidation of Mono-Unsaturates: Reaction 3
30:50
β-Oxidation of Mono-Unsaturates: Reaction 4
31:06
β-Oxidation of Polyunsaturates
32:29
β-Oxidation of Polyunsaturates: Part 1
32:30
β-Oxidation of Polyunsaturates: Part 2
37:08
β-Oxidation of Polyunsaturates: Part 3
40:25
Fatty Acid Catabolism III

33m 18s

Intro
0:00
Fatty Acid Catabolism
0:43
Oxidation of Fatty Acids With an Odd Number of Carbons
0:44
β-oxidation in the Mitochondrion & Two Other Pathways
9:08
ω-oxidation
10:37
α-oxidation
17:22
Ketone Bodies
19:08
Two Fates of Acetyl-CoA Formed by β-Oxidation Overview
19:09
Ketone Bodies: Acetone
20:42
Ketone Bodies: Acetoacetate
20:57
Ketone Bodies: D-β-hydroxybutyrate
21:25
Two Fates of Acetyl-CoA Formed by β-Oxidation: Part 1
22:05
Two Fates of Acetyl-CoA Formed by β-Oxidation: Part 2
26:59
Two Fates of Acetyl-CoA Formed by β-Oxidation: Part 3
30:52
XII. Catabolism of Amino Acids and the Urea Cycle
Overview & The Aminotransferase Reaction

40m 59s

Intro
0:00
Overview of The Aminotransferase Reaction
0:25
Overview of The Aminotransferase Reaction
0:26
The Aminotransferase Reaction: Process 1
3:06
The Aminotransferase Reaction: Process 2
6:46
Alanine From Muscle Tissue
10:54
Bigger Picture of the Aminotransferase Reaction
14:52
Looking Closely at Process 1
19:04
Pyridoxal Phosphate (PLP)
24:32
Pyridoxamine Phosphate
25:29
Pyridoxine (B6)
26:38
The Function of PLP
27:12
Mechanism Examples
28:46
Reverse Reaction: Glutamate to α-Ketoglutarate
35:34
Glutamine & Alanine: The Urea Cycle I

39m 18s

Intro
0:00
Glutamine & Alanine: The Urea Cycle I
0:45
Excess Ammonia, Glutamate, and Glutamine
0:46
Glucose-Alanine Cycle
9:54
Introduction to the Urea Cycle
20:56
The Urea Cycle: Production of the Carbamoyl Phosphate
22:59
The Urea Cycle: Reaction & Mechanism Involving the Carbamoyl Phosphate Synthetase
33:36
Glutamine & Alanine: The Urea Cycle II

36m 21s

Intro
0:00
Glutamine & Alanine: The Urea Cycle II
0:14
The Urea Cycle Overview
0:34
Reaction 1: Ornithine → Citrulline
7:30
Reaction 2: Citrulline → Citrullyl-AMP
11:15
Reaction 2': Citrullyl-AMP → Argininosuccinate
15:25
Reaction 3: Argininosuccinate → Arginine
20:42
Reaction 4: Arginine → Orthinine
24:00
Links Between the Citric Acid Cycle & the Urea Cycle
27:47
Aspartate-argininosuccinate Shunt
32:36
Amino Acid Catabolism

47m 58s

Intro
0:00
Amino Acid Catabolism
0:10
Common Amino Acids and 6 Major Products
0:11
Ketogenic Amino Acid
1:52
Glucogenic Amino Acid
2:51
Amino Acid Catabolism Diagram
4:18
Cofactors That Play a Role in Amino Acid Catabolism
7:00
Biotin
8:42
Tetrahydrofolate
10:44
S-Adenosylmethionine (AdoMet)
12:46
Tetrahydrobiopterin
13:53
S-Adenosylmethionine & Tetrahydrobiopterin Molecules
14:41
Catabolism of Phenylalanine
18:30
Reaction 1: Phenylalanine to Tyrosine
18:31
Reaction 2: Tyrosine to p-Hydroxyphenylpyruvate
21:36
Reaction 3: p-Hydroxyphenylpyruvate to Homogentisate
23:50
Reaction 4: Homogentisate to Maleylacetoacetate
25:42
Reaction 5: Maleylacetoacetate to Fumarylacetoacetate
28:20
Reaction 6: Fumarylacetoacetate to Fumarate & Succinyl-CoA
29:51
Reaction 7: Fate of Fumarate & Succinyl-CoA
31:14
Phenylalanine Hydroxylase
33:33
The Phenylalanine Hydroxylase Reaction
33:34
Mixed-Function Oxidases
40:26
When Phenylalanine Hydoxylase is Defective: Phenylketonuria (PKU)
44:13
XIII. Oxidative Phosphorylation and ATP Synthesis
Oxidative Phosphorylation I

41m 11s

Intro
0:00
Oxidative Phosphorylation
0:54
Oxidative Phosphorylation Overview
0:55
Mitochondrial Electron Transport Chain Diagram
7:15
Enzyme Complex I of the Electron Transport Chain
12:27
Enzyme Complex II of the Electron Transport Chain
14:02
Enzyme Complex III of the Electron Transport Chain
14:34
Enzyme Complex IV of the Electron Transport Chain
15:30
Complexes Diagram
16:25
Complex I
18:25
Complex I Overview
18:26
What is Ubiquinone or Coenzyme Q?
20:02
Coenzyme Q Transformation
22:37
Complex I Diagram
24:47
Fe-S Proteins
26:42
Transfer of H⁺
29:42
Complex II
31:06
Succinate Dehydrogenase
31:07
Complex II Diagram & Process
32:54
Other Substrates Pass Their e⁻ to Q: Glycerol 3-Phosphate
37:31
Other Substrates Pass Their e⁻ to Q: Fatty Acyl-CoA
39:02
Oxidative Phosphorylation II

36m 27s

Intro
0:00
Complex III
0:19
Complex III Overview
0:20
Complex III: Step 1
1:56
Complex III: Step 2
6:14
Complex IV
8:42
Complex IV: Cytochrome Oxidase
8:43
Oxidative Phosphorylation, cont'd
17:18
Oxidative Phosphorylation: Summary
17:19
Equation 1
19:13
How Exergonic is the Reaction?
21:03
Potential Energy Represented by Transported H⁺
27:24
Free Energy Change for the Production of an Electrochemical Gradient Via an Ion Pump
28:48
Free Energy Change in Active Mitochondria
32:02
Loading...
This is a quick preview of the lesson. For full access, please Log In or Sign up.
For more information, please see full course syllabus of Biochemistry
  • Discussion

  • Download Lecture Slides

  • Table of Contents

  • Transcription

  • Related Books & Services

Lecture Comments (19)

2 answers

Last reply by: Swati Sharma
Sat Jan 27, 2018 10:16 AM

Post by Swati Sharma on January 21 at 08:23:24 PM

Dear Dr Raffi

I am little confused in understanding the questions. For example in class we did this question : Calculate the PH of 1L solution containing 0.1 M of Formic acid and 0.1 M sodium formate. So in class our professor told us not to convert them into ,moles and so we directly used 0.1 M concentration into the ICE table.

But if the question says for example Calculate the PH of 2L solution containing 10ml of 5M of acetic acid and 10ml of 1M of sodium acetate then we do convert the concentrations such as 5 moles/1lites * 10.0*10 - liters * 1/2litres and we get Molar concentrations. So in your last question the question said 100.0ml of 0.15 M unknown solution so instead of converting 0.15 M into moles I directly used 0.15M and divided by 2 and got 0.075 M and I plugged into ICE tables and I got the same answer. So if I am not wrong if the question phrases such as Calculate the PH of 1L solution containing X M of acid and X M of base is different from question such as Calculate the PH of 1l solution containing Xml of acid and Xml of base. Please could you explain me if I am right.

Respectfully
Swati

1 answer

Last reply by: Temitope Olasusi
Thu Nov 17, 2016 2:40 PM

Post by Temitope Olasusi on November 17, 2016

How do you solve for the antilog?

1 answer

Last reply by: Professor Hovasapian
Tue Sep 27, 2016 5:03 PM

Post by pierre shaouni on September 15, 2016

at 17:24 how did u get the answer from 2.18= ((o.15-h2po4/h2po4)) to be 0.047. i am confused on what was skipped

0 answers

Post by Professor Hovasapian on February 14, 2014

Hi Tejinder.

I hope you're well.

My apologies for the delayed response.

I'm presuming you meant that the only ACIDS you have available have pKas of 8.0 and 6.9 respectively?

In this case, it really depends on whether the Buffer is going to be absorbing Acid or Base during its function as a buffer.

If absorbing base, then you'll have more buffering capacity if you choose 8.0. If absorbing Acid, then 6.9 is better.

Either one is a fine choice though, if there is not going to be too much movement.

I hope that helps. Let me know.

Best wishes.

Raffi

1 answer

Last reply by: Professor Hovasapian
Fri Feb 14, 2014 1:57 AM

Post by Tejinder kaur on February 11, 2014

Hi Professor, I have homework question and I am little confuse on what one to pick. You want a make a buffer with a pH 7.5, but only buffers you have available have pka of 8.0 and 6.9. Which one, if any, would be better choice and why?
I have picked 6.9 because the buffering region include from 5.9 to 7.9 is close to the pH 7.5. Can you please help me? Thanks

4 answers

Last reply by: Aaron Wasielewski
Mon Feb 3, 2014 12:35 PM

Post by Aaron Wasielewski on January 28, 2014

Hi professor, I am just hitting a bit of a snag here with example 2, and perhaps it should be obvious to me, since it is simple algebra, but at the moment it is not. How are you getting the molarity of 0.047 for the dihydrogen phosphate concentration around 16:21? Maybe after I take a break and try it again, it will jump out, like "AH-HA!", but right now it just isn't. Thank you so much for your help!

3 answers

Last reply by: Professor Hovasapian
Tue Jan 28, 2014 3:03 AM

Post by Madeleine Hackstetter on December 15, 2013

Hi Professor, could you please explain the exact algebra you did in Example 2: Total Phosphate Concentration to get the 0.047 M. It's around 16:27 minutes. I tried doing the question on my own and keep getting an incorrect M value but I'm not sure where my algebra is going wrong.
That would be a great help,
Thank you

Example Problems with Acids, Bases & Buffers

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Example 1 1:21
    • Example 1: Properties of Glycine
    • Example 1: Part A
    • Example 1: Part B
  • Example 2 9:02
    • Example 2: Question
    • Example 2: Total Phosphate Concentration
    • Example 2: Final Solution
  • Example 3 19:34
    • Example 3: Question
    • Example 3: pH Before
    • Example 3: pH After
    • Example 3: New pH
  • Example 4 30:00
    • Example 4: Question
    • Example 4: Equilibria
    • Example 4: 1st Reaction
    • Example 4: 2nd Reaction
    • Example 4: Final Solution

Transcription: Example Problems with Acids, Bases & Buffers

Hello and welcome back to Educator.com and welcome back to Biochemistry.0000

On the last lesson, we talked about titrations and buffers, and I said that we were going to spend this particular lesson just doing example problems mostly with buffers, because that is the real important thing in biochemistry.0003

Let's just jump in and get started.0017

OK.0021

As with all problems in the sciences, it's really, really important, I mean, we have certain equations that we deal with, for example in this particular set of problems that we are going to be doing, the Henderson-Hasselbalch equation is going to be the important one, but it's not just about plugging numbers in.0024

As you'll see in a minute, these problems, they can come across as reasonably complicated- they are not.0040

It's very, very important that you understand the chemistry behind it.0046

If you stop and take a look and ask yourself what reaction is taking place, your intuition will guide you.0049

We want the chemistry to guide the mathematics, not the other way around.0056

If you don't exactly understand the chemistry, then you're sort of going to be limited in the number of problems that you'll be able to do.0061

You'll only be able to do the simple ones, but this is biochemistry, and there tends to be a lot of things going on.0067

They are not difficult problems; it's just a question of, again, understanding the chemistry, so let's see what we can do.0074

The first example- let's go ahead and do it in black here.0082

Example 1: glycine and amino acid, those are the constituents of proteins, and we'll be talking about that very, very soon.0088

I'll go ahead and draw out the structure here: H3 and there is a plus charge, there is a C, there is a C, H, H, H.0106

OK.0119

Glycine is often used to prepare buffer solutions in biochemistry.0120

OK.0142

Let's go ahead and concern ourselves with the amino group.0144

Let's concern ourselves with the amino group.0150

So, you notice in this particular thing, you have an OH here, so this is 1 hydrogen that can be pulled off, that is one ionizable group; but notice here, this is NH3+, there is another hydrogen here, so we are going to concern ourselves with the amino group.0161

Let me go ahead and do this in blue.0174

I'm just going to call this whole rest of the thing "R", and I'm just going to write RNH3+, something like that.0180

That is R amino acid glycine- the protonated form of that.0188

So, let's go ahead and write our reaction that is going to take place.0194

Again, we want to be able to understand what's happening as far as a reaction is concerned: RNH3+, and this is going to be in equilibrium with H+ + RNH2.0196

This is the acid, and this is the conjugate base.0212

That is our little bit of a buffer system here.0216

You are going to have a little bit of this and a little bit of that.0219

OK.0221

Now, let's go ahead and ask some questions about this.0222

I’ll give you a bit of information here, the pKA for this, for the amino group, is 9.6.0227

So, nice, simple first question: What is the buffering region or what is the buffer region of the amino group for glycine?0234

Well, we said that the buffer region is pKA + or - 1 unit.0256

The pKA is 9.6, so we're looking at about 8.6 to about 10.6.0263

If we're going to run an experiment that is going to require a pH in that range, glycine buffer is a good buffer.0270

There you go.0279

OK.0281

Now, let's see what we can do.0283

Now, let's get to some quantitative stuff.0284

OK.0287

In a 0.15M glycine solution at a pH equal to 9.2, what percent of glycine is in its protonated form?0288

OK.0323

Let me go ahead and go to red.0325

The protonated form of glycine is this one; that is the one that is protonated.0327

It's the acid; it's the one that has the hydrogen ion to donate.0330

This is the unprotonated form right here, the RNH2.0333

They want to know, in a solution that is set to a 9.2 pH, what percentage of the glycine is in this form?0337

Again, you've got a buffer solution, some of it is going be this, some of it is going to be that, what's the percentage?0348

OK.0352

A percentage is the part over the whole.0354

Let's go ahead and see what we can do here.0356

Let's go ahead and use Henderson-Hasselbalch equation, which is perfect: pH = pKA + log of RNH2, that is the conjugate base, over the acid form, RNH3+, over that.0359

Well, they said that the pH is 9.2, so, that is going to be the left hand side of our equality.0380

The pKA is 9.6 + the log- I'm just going to write base over acid so that I don't have to keep writing over and over again.0386

OK.0397

Well, let me see.0399

Let me go to the next page to actually solve this and rewrite it.0400

I've got 9.2 = 9.6 + the log of the base over the acid, and now, I'm going to go ahead, and I'm going to solve for this ratio- the base over the acid.0403

Because they are asking for percentage, they are asking for a fraction, I'm just going to go ahead and leave it as that; because this base over the acid, that is our percentage.0418

So, when I solve this 9.2 - 9.6 = -0.4, right?0427

This is going to be -0.4 = log of b/a.0433

Now, I'm going to take the antilog, I'm going to raise both side, I'm going to exponentiate with the base 10; and what I end up with is the following.0440

I end up getting that the, well, this is going to be 0.398 = RNH2/RNH3+.0449

OK.0469

Now, what does this mean?0470

This ratio here is telling me the ratio of base, unprotonated to protonated, is 0.398.0472

This is a part over the whole.0480

That means that 39.8% is unprotonated.0482

That is what a percent is- it's just the part over the whole.0493

In this particular case, how much of that is unprotonated?0496

Well, they didn't ask for the unprotonated, they asked for the protonated, so now, I just subtract this from 100 and what you get is: 60.1% is protonated.0500

In this particular case, I used the Henderson-Hasselbalch equation.0512

I used the ratio itself; I didn't actually solve for the numerator or denominator.0518

I used the ratio itself, because the problem asked for a percentage, and a percentage is a part over the whole.0522

I hope that made sense.0530

OK.0531

Let's do something a little bit more complex here- example number 2.0534

Let me go back to blue here.0540

Example number 2: how much in grams, actually - so, let me just write how many grams - how many grams of sodium dihydrogen phosphate and how many grams of disodium hydrogen phosphate are needed to prepare 1.0L of a pH = 7.20 buffer, with the condition that the total phosphate concentration must be 0.15M?0547

OK.0637

When you read this question, you're probably thinking to yourself "Oh my God, how the heck am I going to solve this? There's a lot going on here?".0639

OK.0645

This is where it's really, really important to take your time, relax, don't think that you have to look at this question and just automatically know what to do.0646

You want to think about this, think about the chemistry, think about what's going on; and see if we can interpret what it is this thing is actually saying here.0655

Here we're trying to prepare a buffer, 1L of that buffer- that is nice, 1L, that is good.0666

We want the buffer to be half a pH of the final pH of 7.2.0672

Well, I'm going to be adding some sodium dihydrogen phosphate and some disodium hydrogen phosphate, so I know that my buffer here is going to be the H2PO4 and the HPO4, the phosphate buffer.0677

It looks like this experiment is trying to mimic what is going on inside of a cell.0689

So, I'm going to add a little bit of dihydrogen phosphate, a little bit of hydrogen phosphate.0695

I need to know how many grams I need to add to 1L in order to get myself to a pH of 7.2, but I have a condition: I need the total phosphate concentration to be 0.15M.0700

OK.0714

Let's just go ahead and write down some equations, and see where we can go.0715

And again, sometimes you just have to start with what you do know, and hopefully, something will fall out.0719

I'm going to write down the equation- my buffer equation: H2PO4-, that is going to be in equilibrium with H+ + HPO42-, right?0724

This is my acid; this is my conjugate base.0736

This is my proton donor; this is my proton acceptor.0739

Well, I need the total phosphate concentration.0743

I need it to equal 0.15M.0753

What that means is the following: that means the total concentration of H2PO4- plus the concentration of HPO42- -, the sum of those, that is what that means.0757

A lot of these problems in biochemistry, the difficulty is not going to be the chemistry; it's going to be interpreting what it is that it's going to ask.0774

So, questions can be asked in several different ways.0780

One of the things that you will see in biochemistry, in books, in journals, in things like that, when they talk about the total phosphate concentration or the total carbonate concentration, they are talking about all the different species.0783

In this case, the phosphates that we are dealing with, it isn’t PO43--; the only phosphate species we have is the dihydrogen phosphate and the hydrogen phosphate, so the total phosphate means the sum of those two, this and this.0795

They have to add up to 0.15.0809

That is what that part means in the question.0811

OK.0813

Let me go ahead and do...I'm going to do something here.0816

I'm actually going to move one of these over, and I'm going to solve for HPO42-.0823

The hydrogen phosphate concentration, HPO42- - and again, be very, very careful, there's a lot of symbols going on here- 0.15 minus the concentration of the dihydrogen phosphate.0829

So, that's that.0844

Now, I can go ahead and write down the Henderson-Hasselbalch equation, and I should be able to work this out.0847

Let's go ahead and write down pH = pKA plus the logarithm of the base, which is HPO42- over the acid, which is the H2PO4-, right?0853

OK.0877

We want the pH to be 7.2, so we have that number.0878

We have the pKA of this buffer system; we can just look it up.0883

This is actually the second ionization of phosphoric acid, so the pKA happens to be 6.86 plus the log; and now, I've already expressed HPO4 in terms of this, so I’m going to write 0.15 - H2PO4- over the concentration of H2PO4-.0885

Notice what I did, is I ended up replacing two different variable here by one variable by knowing that the total phosphate concentration was 0.15, so now, I just have H2PO4-.0913

Well, I have a perfectly good equation here.0925

This is my variable, the concentration of the dihydrogen phosphate.0927

I'll just go ahead and solve for that.0930

I end up with the following: 2.1 - I'll go ahead and work it out to a reasonable degree - so, I have 2.188 is equal to, once I actually move this over, take the antilog, I'm left with 2.188 = 0.15 - H2PO4-/H2PO4-.0933

OK.0965

And so, I'm going to go ahead and let you do the algebra here, move this over, this is just simple algebra.0966

I end up with a dihydrogen phosphate concentration equal to 0.047M.0970

So, I know that that's the concentration of the dihydrogen phosphate I need, in order to get a 7.2 buffer.0981

OK.0989

Well, since I know the dihydrogen phosphate, now, I can just do the 0.15 minus this.0990

I also know the hydrogen phosphate, so HPO42- concentration, that equals 0.15 - actually, let me do that one in red just to keep them separate - 0.15 - 0.047 and that is going to equal 0.103M.0996

There is our concentrations that we need, but we want it grams, we didn't want concentration in moles per liter.1023

So, let's go ahead, and now deal with the sodium dihydrogen phosphate.1030

OK.1038

I have 0.047mol/L, and the molar mass of the sodium dihydrogen phosphate is 120g/mol, and it was going to be in 1L of solution.1040

This is why I said "I'm really happy that it is 1L, it's a very, very nice number - 1.".1057

Well, liter cancels liter, mole cancels mole.1062

I'm left with grams and my answer there is going to be 5.64g of sodium dihydrogen phosphate- that is my first answer.1065

Now, I want to do my disodium hydrogen phosphate.1080

Well, this one is 0.103mol/L, and its molar mass is 142g/mol, and of course, we are creating 1L of solution; so again, mole cancels mole, liter cancels liter - oops, sorry about these little stray lines here, they tend to show up - and here, we get 14.63g.1088

There we go.1119

In order for the total phosphate concentration to be 0.15M, using the phosphate buffer system, dihydrogen phosphate and hydrogen phosphate at a pH of 7.2, I need to add 5.64g of sodium dihydrogen phosphate to 1L of solution, and I need to add 14.63g of disodium hydrogen phosphate, and I will prepare this 7.2 pH buffer.1120

That is it.1150

I'm just using the Henderson-Hasselbalch equation and trying my best to extract as much information as I can and play around with it.1151

I hope that makes sense.1159

It's a little long, but there's nothing strange going on, and certainly nothing strange mathematically, it's just simple algebra.1160

OK.1166

Let's move on to another example here.1168

Let's see.1175

Example number 3: what is the change in pH when 6.0mL - actually you know what, let me write, I don't want to separate my unit from my number - when 6.0mL of a 0.5M hydrochloric acid is added to 1.0L of a lactic acid buffer solution containing 0.03mol of lactic acid and 0.05mol of lactate.1176

And in this particular case, the pKA of lactic acid is 3.86.1256

OK.1267

So, what's the change in the pH when 6mL of a 0.5M hydrochloric acid is added to 1L of a lactic acid buffer solution that contains 0.03mol of lactic acid and 0.05mol of lactate?1268

OK.1281

It seems kind of complicated, a lot of numbers floating around.1283

What's nice about this, I noticed that they gave us the moles of the lactic acid and the moles of the lactate.1287

That is really, really good.1293

Let's write our equation, first of fall, so we understand what's going on.1296

We are looking at a lactic acid solution, so, I'm just going to write that as HLac, and that is in equilibrium with H+ + Lac-.1299

OK.1311

That is our equation.1312

This is our acid, the lactic acid, and this is our conjugate base, so the R buffer solution contains a little bit of this and a little bit of that.1316

And, what's nice is they actually told us how much- it's 1L of solution.1321

That is fantastic, that works out well.1325

They want a change in pH, so we need the pH before, we need the pH after.1329

Let's go ahead and calculate the pH before the addition.1334

OK, and again, we're going to use the Henderson-Hasselbalch.1345

Again, pH = pKA plus the logarithm of the base, which is the lactate, over...you know what, I hope you'll forgive me, I'm going to stop writing these brackets, I think of at this point it should be pretty clear we're dealing with concentrations, moles per liter, so, I'm just going to go ahead and write Lac- over HLac without the brackets, but again, we're talking about concentration- moles per liter.1347

Well, the pKA is 3.86 - that is great - and plus the logarithm of the lactate concentration is 0.05mol/1.0L, and the acid concentration was 0.03mol, so this is 0.03mol/1.0L.1375

Here is what's really nice, when the volume doesn't change because they are both in the same container, so for all practical purposes, we can just work with moles.1401

We don't have to worry about concentration.1409

In other words, even if I were to add, let's say here I'm going to add 6mL, so now, there is an extra 6mL, but the volume is the same.1411

You are dividing by the total volume, so the volume and volume actually cancel, so we can just work with moles.1420

That is the nice thing about the Henderson-Hasselbalch equation.1426

The volume actually cancels, but I want you to see that you are actually dealing with concentration, a certain number of moles per 1L.1428

OK.1437

So, when we do this, we end up with 3.86 - and by all means, please check my arithmetic here, I'm notorious for arithmetic errors - plus 0.223, and we get an initial pH of 4.08.1439

That is our initial pH before the hydrochloric acid was added.1456

OK.1460

Now, let's go ahead and calculate the pH afterward.1461

OK.1464

Now, for the pH after the addition of the hydrochloric acid.1465

So, here is where it's really, really important- we have to stop and ask ourselves what is it that's happening.1475

This is a buffer solution, so when we add hydrochloric acid, we're adding H+.1479

Well, we have to stop and ask ourselves what the chemistry, what's taking place?1485

So, the H+ is going to react with either the lactic acid or the lactate in order to be used up.1489

Well, it's going to react with the lactate.1497

The reaction upon addition of the H+, we add the hydrochloric acid, but the chloride doesn’t matter, it's the H+ that matters.1501

And, the H+ is as follows: we have H+ is going to react with the lactate to produce lactic acid.1516

Now, we have to find out how much of this lactate is actually converted to lactic acid, we calculate our mole ratios, so that we can find our new pH.1531

We're going to working with moles, so we're going to have it before the addition of the hydrochloric acid.1540

We're going to have the change that takes place, and we're going to have the afterward.1546

Well, before, our lactate concentration is 0.05mol, and our lactic acid concentration is 0.03mol, now, our H+ concentration happens to be 0.003mol, and you're probably wondering where I came up with that.1551

Well, I'll show you where I came up with that.1574

OK, remember we said we're adding 6mL of a 0.5M hydrochloric acid solution, so 6mL is 0.006L x 0.5mol/L.1577

0.006 x 0.5 gives me 0.003mol of HCL were added, which means 0.003mol of H+.1592

This is before any reaction takes place.1606

Now, this reaction goes to completion.1608

All of the hydrogen ion is eaten up, that is what a buffer does- leaving no free hydrogen ion.1613

Lactate 0.003 reacts with the lactate leaving - it's the lactate that is converted, so that is going to deplete - that is going to end up leaving me with 0.047mol of the lactate, and this is going to be plus 0.003, because now, lactic acid is being produced.1621

It is being produced that much, so we end up with 0.033mol of lactic acid.1646

So, the buffer solution stands at a certain pH, I add some hydrogen ion.1655

Some hydrogen ion converts some of the lactate to lactic acid.1660

I need to find out how much is converted.1664

I need these numbers - the final mole amounts.1665

Now, I can run my Henderson-Hasselbalch equation to get my new pH.1669

OK.1673

Let me do it over here; so, pH equals - again, I'm just going to keep writing this equation over and over again: pKa plus the logarithm of the lactate over the lactic acid, it equals 3.86 plus the logarithm of, well, lactate is 0.047, and again, this is moles, but again, because the volume is the same, even though I've added 6mL, so now, I have 1L + 6mL, so I have 1006mL, the volume is the same.1677

So, even if I divide by the volume here to get molarity, because these are concentrations, the volumes cancels, so I can just work with moles, the volume is irrelevant...over 0.033mol.1730

And when I run this, I end up with 3 - I don't need to write out everything - I end up with the pH of 4.01.1745

My initial pH was 4.08; my final pH was 4.01, so my delta pH, my change in pH is -0.07.1758

Yes, as you see, this is a fantastic buffer.1771

I've added 6mL of a 0.5M hydrochloric acid solution.1774

That is actually a lot of hydrochloric acid, and yet the pH has gone down just a little bit, barely anything to be noticeable.1779

This is a perfectly functioning buffer solution.1786

OK.1790

Now, let's go ahead and do one last example here.1793

Do this one in blue.1802

Example 4, now, OK.1806

An unknown compound has 2 ionizable groups.1813

In other words, there are 2 sets of hydrogen ions that it can lose, that can be taken away.1826

OK.1833

It's an unknown compound.1834

Now, the pKA1 is equal to 2.5. - that much we do know, the first ionizable group.1836

Now, when 85.0mL of a 0.1M sodium hydroxide is added to 100.0mL of a 0.15M solution of this unknown compound, which is already at a pH = 2.5, its pH jumps to 6.82.1845

My question to you is: what is KA2 or pKA2?1911

See here, did I give you KA...yes that is fine.1925

What is the pKA2?1927

OK.1931

We have an unknown compound that has two ionizable groups.1932

We happen to know that the first ionizable group has a pKA of 2.5, now, when we add 85mL of a 0.1M sodium hydroxide to this 100mL of a 1.5M solution of this unknown compound, which is already at a pH of 2.5, its pH jumps to 6.82.1936

What's the pKA2?1955

OK, let's see what we have going here.1958

I'm going to go ahead and assign a...let me do, that is fine, I'll go ahead and keep it as blue.1960

I need a symbol for this, so let H2A be the unknown compound.1971

OK.1984

The equilibria are as follows.1985

In this particular problem, we definitely need to keep track of the chemistry.1989

The chemistry is what's important.1993

It will decide what the math looks like.1994

The equilibria are as follows: we have the 1st dissociation, H2A goes to H+ + HA-; and we know that this pKA, we know that one, that is equal to 2.5.1999

And then of course, we have the second ionization: HA- in equilibrium with H+ + A-.2020

This is the pKA that we seek.2028

So, we have number 1- we seek that.2031

OK.2036

Well, notice what we have.2040

They are telling me that the pH of this solution - let me go to red here - is already 2.5.2043

Well, as it turns out, the pKA of the first ionizable group is 2.5.2049

This is very, very convenient.2055

So, at pH equal to 2.5, the H2A concentration is equal to the HA- concentration, right?2057

This is half equivalence.2076

When the pH equals the pKA, then what you have is, that and that have the same concentration.2077

OK.2086

Well, let's see what else we can do with that little bit of information.2087

So, we have a 0.15M solution of this unknown compound, and it also gives us the volume.2093

Oh good, OK.2102

So, we have 0.100L x 0.15mol/L, so when I multiply this out, I end up with 0.015mol of H2A to begin with.2106

You know what, I have a lot of lines floating around, so I'm going to actually do this on the next page; I hope you don't mind.2134

I want you to be able to see the math and not have it be...OK...let me actually do it down here, and see if it works a little bit better.2142

I have 100mL, 0.1L x 0.15mol/L, that gives me 0.015mol of H2A to begin with.2152

That is what this means: 100mL of a 0.15M solution to begin with, I have 0.015mol of H2A.2174

Well, I know that at pH of 2.5, the pKA is 2.5, so I know that my H2A is actually equal to this; so, half of this H2A originally, has been converted to its conjugate base.2182

Therefore, if I have 0.015 to start off with, if I take half of the 0.015, that means I have 0.0075mol of H2A, and I have 0.0075mol of HA-.2198

That is before anything happens.2224

The pH of 2.5 happens to match the pKA; I know that that is half equivalence.2227

Therefore, I know that acid and the conjugate base concentrations are equal.2231

I started off with 0.015mol; I've converted half of it.2234

That means now, that is what I have.2238

OK.2241

Now, let's move forward from here.2242

Well, let's go ahead and concentrate; let's see how much hydroxide ion was added.2245

Hydroxide ion, they said we added 85mL of a 0.1M, so 0.085L x 0.1mol/L; liter and liter cancels, leaving me with 0.0085mol of OH- were added.2252

OK.2276

Well, this is a buffer solution; now, I'm adding a base.2277

When I add a base, it's going to react with the acid.2280

Here is what's going to happen.2285

Again, you have to reason out the chemistry; that is the only way this problem is going to be solved.2287

Well, the first reaction is going to be, the hydroxide that is added is going to react with the H2A, that is left over, the little bit that is there; because that is the first ionization, H2A, and it's going to produce H2O + HA-.2298

We're going to have a before; we're going to have a change, and we're going to have an after.2319

Well, before, our concentration is 0.0075, 0.0085 of the hydroxide, the water doesn't matter, and I have 0.0075 of that.2324

Well, 0.0075, 0.0085, this is the limiting reactant, so it's going to run out first.2340

So, the change is that, there's going to be no H2A left over, 0.0075, there's going to be 0.0010mol of hydroxide left over.2347

Water doesn't matter; here it's going to be converted, so it's going to be +0.0075.2364

This H2A, all of it is going to be converted to HA, so now I have 0.015mol of the HA-.2372

OK, but notice, I still have some excess hydroxide.2384

Hydroxide is going to go after any other hydrogen ion it can find.2387

So, there's a second reaction that takes place here.2393

Now, this hydroxide is going to react with this.2398

So, the second reaction that takes place is: the leftover hydroxide is going to react with the HA-, and it's going to convert it to water + A-.2401

Well, I have a before, I have a change, I have an after.2416

Before, I start with 0.0010mol of that HA, I have 0.015mol of that, water, of course, does not matter; and I have none of this.2421

Well, in this case, 0.0010 is the limiting reactant, so that is going to drop to 0 - 0.0010.2437

This is going to be converted, that is why this is a minus, so we end up with 0.014mol of HA.2447

Now, in this particular reaction, it's the HA that is the acid donor, and this is the conjugate base.2457

Up here, the HA is the conjugate base, and this is the acid.2465

OK.2469

So now, we have the 0, and then we have +0.0010, so this is going to be 0.001.2470

Now, we have a certain amount of A-- that much.2480

We have a certain amount of HA- that is that much.2483

Now, we can go ahead and do our thing.2486

Let me go ahead and we're going to write out again the Henderson-Hasselbalch equation: pH= pKA + the log of the A2- over the HA-.2492

I apologize, I may have left the 2-; it lost a second proton, so now, it has a 2-charge on there.2513

Well, they said the pH jumps to 6.82.2518

Well, we're looking for the pKA2, that is what we're looking for, plus the logarithm of the...so now, the A2-.2525

We said we had 0.001mol, right?2535

And this time, I'm actually going to put it there.2542

So you see, I had 100mL of solution to start, I added 85mL, so now, my total volume is 0.185L - and you'll see in a minute, it actually cancels out, but I wanted you to see that it's there, I don't have to put it there, I can just work with the moles, but I do want you to see it - over 0.014mol, over 0.185L, volume, so those go away.2544

They don't really matter.2571

So, what I'm left with is 6.82 is equal to the pKA2 that I seek, plus a -1.15.2573

That means that my pKA2 is equal to 7.97 if I had done my arithmetic correct.2586

There you go.2595

I had a solution whose pH happens to match the first ionization- the pKA1 of an unknown compound.2597

I added a certain amount of hydroxide to this buffer solution, and now, the pH jumped up to 6.82.2605

Well, I used the fact that, basically, what you have is a titration, you have a buffer; however, I need to keep track of what's going on.2613

I need to find out the number of moles, how much of one species is being converted to another, how much hydroxide is left over.2621

Because there was some hydroxide left over upon the first reaction, the leftover hydroxide was going to react with the next species that has hydrogen ions to give up, until all of the hydroxide is used up, is eaten up, is sequestered; and then what you're left with, was of course, this, giving us a way to actually find the pKA.2629

OK.2654

Thank you so much for joining us here at Educator.com.2656

We'll see you next time, bye-bye.2658

Resetting Your Password?
Educator®

Please sign in for full access to this lesson.

Sign-InORCreate Account

Enter your Sign-on user name and password.

Forgot password?

Start Learning Now

Our free lessons will get you started (Adobe Flash® required).
Get immediate access to our entire library.

Sign up for Educator.com

Membership Overview

  • Unlimited access to our entire library of courses.
  • Search and jump to exactly what you want to learn.
  • *Ask questions and get answers from the community and our teachers!
  • Practice questions with step-by-step solutions.
  • Download lesson files for programming and software training practice.
  • Track your course viewing progress.
  • Download lecture slides for taking notes.

Use this form or mail us to .

For support articles click here.