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Raffi Hovasapian

Raffi Hovasapian

Acids & Bases

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
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Lecture Comments (17)

1 answer

Last reply by: Professor Hovasapian
Wed Feb 8, 2017 12:00 AM

Post by Kapil Patel on January 31, 2017

hi professor Hovasapian i have question the ph practice problems can you help me  
answer this questions? thank you

question number 1. If I have a solution with a pH of 4, what is the hydrogen ion concentration ([H+]), hydroxide concentration ([OH-]) and pOH?

question number 2. If I have a solution with a pH of 8, what is the hydrogen ion concentration ([H+]), hydroxide concentration ([OH-]) and pOH?

question number 3. If I have a solution with a pH of 11, what is the hydrogen ion concentration ([H+]), hydroxide concentration ([OH-]) and pOH?

question 4. If I have a solution with a pH of 2, what is the hydrogen ion concentration ([H+]), hydroxide concentration ([OH-]) and pOH?

question 5. If I have a solution with a [H+] of 1x10-3, what is the pH, hydroxide concentration ([OH-]) and pOH?

question 6.If I have a solution with a [H+] of 1x10-5, what is the pH, hydroxide concentration ([OH-]) and pOH?

question 7. If I have a solution with a [OH-] of 1x10-3, what is the pH, hydrogen ion concentration ([H+]) and pOH?

question 8.How much stronger is an acid with e pH of 3 then one with a pH of 6?

and question 9.How much strong of a base is a solution with a pH of 12 then one with a pH of 7

2 answers

Last reply by: rew node
Sat Nov 22, 2014 10:05 AM

Post by rew node on November 21, 2014

can you explain  equation of strong base
why is not left
cus i don't get it this equation

1 answer

Last reply by: Professor Hovasapian
Fri Jun 20, 2014 4:41 PM

Post by Catherine Hand on June 20, 2014

There is quite a few subjects I am not following.  Especially the Henderson-Hasselbach equation, parts is because i do not know how to do the negative log calculations.  Is there another course I should of done first?

2 answers

Last reply by: Catherine Hand
Fri Jun 20, 2014 9:30 AM

Post by Donna Karein on August 2, 2013

I am trying to find how you got 3.98 sorrry

2 answers

Last reply by: tiffany yang
Sun Sep 29, 2013 4:52 PM

Post by Nawaphan Jedjomnongkit on May 6, 2013

Hi Professor, you mention that the acid and base reaction the only thing that move is H+ so what happen if in acid base reaction that does not have H+ like in Lewis acid or base? Will we still use Ka Kb in this situation? and how about the pH or pOH?

0 answers

Post by Professor Hovasapian on March 29, 2013

Hi Marsha,

I hope you're doing well.

Ka values have been calculated experimentally and placed in tables -- usually in the appendices at the back of the book -- or shorter versions within the chapter itself. If you don't find it in the back of your Biochem text, you'll most certainly find it in the back of your General Chem Text -- the Title of the table will be something like "Stepwise Dissociation Constants for Several Common Polyprotic Acids". The second dissociation Constant for Phosphoric Acid (Ka2) is listed as 1.38 x 10^-7.

I hope that clears it up. if not, let me know, and I'll remedy the situation.

Best wishes, always, and take good care.

Raffi

2 answers

Last reply by: Professor Hovasapian
Fri Mar 29, 2013 5:33 PM

Post by marsha prytz on March 29, 2013

Prof Hovasapian, I am confused as to how you got the Ka2 of 1.38 x 10-7 result. Can you explain to me or show me how that result came about? Thanks Marsha

Acids & Bases

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
  • Acids and Bases 1:16
    • Let's Begin With H₂O
    • P-Scale
    • Example 1
    • pH
    • Strong Acids
    • Strong Bases
    • Weak Acids & Bases Overview
    • Weak Acids
    • Example 2: Phosphoric Acid
    • Weak Bases
    • Weak Base Produces Hydroxide Indirectly
    • Example 3: Pyridine
    • Acid Form and Base Form
    • Acid Reaction
    • Base Reaction
    • Ka, Kb, and Kw

Transcription: Acids & Bases

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

Today we are going to start talking about acids and bases.0004

This is going to be a reasonably quick review, because again, we just want to get our feet wet, get used to some concepts from general chemistry before we actually dive into the biochemistry proper.0008

Acids and bases, acid base chemistry is profoundly, profoundly, profoundly important.0019

We are going to be going through most of the stuff that you've seen.0025

We are going to be talking about pH.0028

We are going to be talking about how acids and bases behave.0030

What I'd like you to take away from the notion of acid-base chemistry is how acids and bases actually behave and the idea that the only thing that moves in an acid-base reaction is the proton- is that hydrogen ion.0033

If you can concentrate just on that aspect, you can use what you know - your intuition that you've gained from general chemistry and from organic chemistry - to actually understand a huge amount of biochemistry.0047

Don't get lost in the details here.0061

I mean, yes, the details are important, but what's important is understanding that it's only a proton that is moving.0063

That's it; that's the only thing that's going on here.0069

That's the important part to take away from this.0073

OK, let's go ahead and start our review.0075

Let's go ahead and begin with water.0078

Let's begin with H20.0089

OK.0094

H20, water, in solution, actually dissociates a little bit.0096

It releases a free hydrogen ion, and it releases a free hydroxide ion.0102

We write that this way: H+ + OH-.0109

Now, you remember from general chemistry, we want to be able to have some sort of numerical measure of the extent to which something dissociates.0117

In other words, how much H+, how much OH-, is floating around in water.0126

Well, you remember there is something called the equilibrium constant, you have some reaction, what you do is you take the concentration of the products raised to their stoichiometric coefficients, divided by the reactants, raised to their stoichiometric coefficients.0131

Now, let me go ahead and put some state symbols here, this is aq, and this is aq; and you remember of course, when we have liquids or solids, they actually don't show up in the equilibrium expression.0145

So in this case, our Keq is going to equal the concentration of H+ times the concentration of OH-; but again, this is liquid so it doesn't show up in the denominator, so that's all.0157

Now, we call this, because it's for water, we give it a special symbol Kw.0172

We have measured this, and it's actually equal to 1.0 x 10-14 at 25°C.0176

At 25°C, this ion product constant, this dissociation constant for water happens to be 1.0 x 10-14.0186

That is a very small number.0196

What that is telling you is that most of it stays as water, but a little bit of it, very, very little, dissociates into that.0199

OK, that's it.0206

This is a very, very important relation.0210

Now, in any and every aqueous solution, the hydrogen ion concentration times the hydroxide ion concentration has to equal 1.0 x 10-14.0212

In other words, if the hydrogen ion concentration rises for some odd reason, the hydroxide ion concentration drops, because their product has to equal a constant.0234

That's what this whole idea is.0247

A constant is something that doesn't change.0249

The particular values of the individual species involved in the constant, they might change; but their product doesn't change.0252

If one goes up the other has to go down.0258

OK.0262

Now, let's introduce something called the p-scale.0264

You already know this, but we will mention it anyway.0266

We talked about pH and that's equal to -log of the hydrogen ion concentration.0272

Again, hydrogen ion concentrations are generally very small, things like 2.6 x 10-3, very tiny numbers.0282

So, instead of dealing with those numbers, they developed this idea of a p-scale because they wanted to deal with numbers that are just more natural like 6.2, 10.6, things like that.0289

It doesn't really matter.0300

I personally prefer to deal with concentrations directly, as opposed to taking the negative logarithm of them and using the p-scale; but in biochemistry, they tend to use the p-scale almost exclusively.0303

That's all it is, it's just the -log of whatever concentration.0316

We also speak of a plH, that's the -log of the hydroxide ion concentration.0319

You can also talk about, let's say pCl, that's equal to the -log of the chloride concentration.0325

It could be p-anything, so p-scale, but most of the time, we talk about pH.0334

We pick one thing to discuss as our standard in a particular aqueous solution.0339

We've chosen the hydrogen ion concentration as the standard against which other things are measured.0344

OK, so let's see.0350

If a hydrogen ion concentration times the hydroxide ion concentration in any aqueous solution is equal to 1.0 x 10-14, well, in terms of pH, if I take the negative log of both of these, I get the following.0354

I get the fact that the pH plus the pOH of an aqueous solution is equal to 14.0371

They're the same thing.0378

One deals with the concentrations directly; the other deals with a different representation of concentration.0379

That's all.0386

OK.0388

A pH of...well, actually, I'll introduce that in just a second.0390

OK, so let's see what we have here.0397

Let's do an example just really quickly.0399

OK.0405

The pH of a glycine solution - glycine is an amino acid and we'll get to that in just a couple of lessons when we start to discuss proteins - is measured to be 5.4.0408

OK.0432

The question for us is "What is the hydroxide ion concentration in the solution?".0433

OK.0441

Well, nice and easy; we just use this- right here.0446

That's our basic relation.0453

If the pH of our solution is equal to 5.4, well, that implies that 5.4 equals -log of the hydrogen ion concentration; that's the definition, right?0459

Let's go ahead and take the antilog raise it to power, that means that the hydrogen ion concentration is equal to 10-5.4, right?0474

Move the negative sign over antilog; just raise, take 10 to that particular power and when we do that, we get 3.98 x 10-6M.0486

So, the concentration of the hydrogen ion in this particular glycine solution is 3.98 x 10-6mol/l.0502

OK.0509

Well, we know that the hydrogen ion concentration times the hydroxide ion concentration is equal to 1.0 x 10-14.0511

Therefore, the hydroxide ion concentration equals 10-14 divided by the hydrogen ion concentration, which is 3.98, times 10-6; and when we do this calculation, we get 2.51 x 10-9M.0524

That's it.0550

Nice and simple, basic relation.0554

Hydrogen ion concentration times the hydroxide ion concentration at 25°C is 10-14.0556

If I have one, I have the other.0562

If I wanted to go to the pH, if I wanted to, let's say, do the pOH, what I would get is the following: pOH, I would just take the -log of this hydroxide ion concentration and I get 8.6.0565

Nice, straight-forward, nothing strange going on here.0578

OK.0584

Now, let's talk about the pH scale.0587

Any pH from 0 to 7, we call that an acidic solution.0592

The pH of 7 is called a neutral solution, and the pH of 7 to 14 is called a basic solution.0599

What that means in an acidic solution, the hydrogen ion concentration is greater than the hydroxide ion concentration; they're not equal.0613

In a neutral solution, the hydrogen ion concentration actually equals the hydroxide ion concentration- 10-7 = 10-7, 10-7 x 10-7 = 10-14.0621

That's where this scale comes from, 0-14.0636

It is based on that.0638

Actually it's based on that number.0642

And, a basic solution is when the hydrogen ion concentration is less than the hydroxide ion concentration; or another way of thinking about it, when the hydroxide ion concentration exceeds that of the hydrogen ion concentration.0646

No matter what they are, they multiply to 10-14 at 25°C.0658

Different temperature, it's a different Kw.0664

OK, good.0667

Now, let's go on and discuss strong acids.0671

Strong acids are acids that completely - ooh, might be nice if I actually knew how to write here, Oh my God, what is happening?- let's try this again.0682

There we go.0701

Strong acids are ones that completely dissociates when put into water.0703

In other words, if I take some hydrogen chloride and if I drop it into water, what happens is that it actually becomes an aqueous solution of hydrogen chloride; and then it completely dissociates into H+ and Cl-.0715

This is actually a two-step process.0732

I take the pure hydrogen chloride- see this is the thing, when we speak of things like HCl, H2SO4, H3PO4, we refer to them as acids; because 100% of the time in our dealings with them, we're going to be dealing with them as solutions.0734

As solutions they are acids; they are acids when they dissociate.0751

When they're like this in pure form, they're not acids.0755

We still name them as such, but what happens is when we speak about acids, we're speaking about an aqueous solution.0757

We've taken this thing and we've dropped it into water, and then first of all, it becomes solvated; water surrounds it, and then water takes it apart- it breaks up.0763

Anything that completely dissociates, in other words, when there is no HCl left, we call it a strong acid, because it completely separates into free ions.0772

Another example would be HNO3; I'm going to skip this part.0782

H+ + NO3-, a strong acid, when you drop this in the solution or when you drop this into water, into a solvent, all of this comes apart; there is none of this left.0788

There is only H+ floating around and NO3- floating around in a nitric acid solution.0799

That's what's happening.0806

Strong acids don't have an equilibrium constant precisely because there is no reactant left over to be used as the denominator of the equilibrium constant.0808

Anytime, if you're looking through a list of equilibrium constants for acids, then if it's not there, it's a strong acid.0820

That is pretty much how you tell.0831

OK.0833

A strong base, same thing, except instead of complete dissociation, instead of producing hydrogen ion, they produce hydroxide ion.0836

An example would be sodium hydroxide, it completely dissociates into sodium plus hydroxide ion, OH-.0847

That's it.0858

There is none of this left.0860

The only thing you have floating around in a sodium hydroxide solution is a bunch of sodium ions which are harmless; and then you have the hydroxide ions which are not harmless.0861

OK.0872

Now, we're going to get to the important stuff: weak acids and bases.0873

This is where everything gets really, really exciting- weak acids and bases.0875

Well, weak acids and bases, exactly what you think it is; weak acids and bases are ones that don't completely dissociate.0887

However, before I discuss that, I'm going to write down the thing that I mentioned early on before we started this lesson, the only thing that moves.0896

The only thing that moves in acid-base reactions is H+- the proton.0908

Remember that.0921

The only thing that moves is the H+, that's it.0923

H+ is going to bounce from one species to another species.0925

The species that it goes away from is the acid; the species that it actually goes to is the base.0929

That is all the acid-base base chemistry is about, the rest is just math.0934

OK.0939

Let's talk about weak acids.0943

I'm actually going to start this on another page, and I'm going to go to a blue ink.0946

I'm going to start with an example as opposed to a definition.0954

And again, a weak acid is one that just doesn't dissociate completely, so I'm going to use hydrofluoric acid as my example.0960

HF + H2O, when I take hydrogen fluoride, I drop it in water, a reaction takes place between hydrogen fluoride and water.0965

Hydrogen fluoride gives up its hydrogen ion, water takes the hydrogen ion.0976

This is the acid; this is acting as the base.0982

What you get is the following: H3O+ + F-.0987

Now, I'm going to write this in another way.0993

I wrote it this way simply because the reaction that is actually taking place is this.0995

Anytime there is an acid, there is also a base.1001

The acid is the thing giving the hydrogen ion, the base is the thing taking it.1003

In this reaction, hydrogen fluoride is acting as the acid, H2O is acting as the base.1007

What you get is a hydronium ion, and you get F-.1011

There is another way that we actually write this which tends to be a little bit more popular in biochemistry1015

When dealing with weak acids, they generally drop this H2O part and they write it like this: HF ⇌ H+ + F-.1023

They say that this hydrogen fluoride dissociates a little bit to produce some hydrogen ion and some fluoride ion.1033

Now, notice this equilibrium arrow- this is in equilibrium.1039

It doesn't go to completion; all of it doesn't dissociate.1042

In fact for weak acids, most of it does not dissociate; very little, in fact, dissociates.1046

We can write an equilibrium expression for this.1052

By the way, this is aq, and this is aq, and this is aq.1056

So, everything shows up in the equilibrium expression.1061

The equilibrium expression for an acid is, for this one is H+F-, actually for all weak acids, it's going to be the hydrogen ion concentration times the conjugate base concentration, over the concentration in moles per liter of the original acid; so it's products divided by reactants.1065

Well, it's an equilibrium expression; but because we are talking about standard acid reaction, we actually call it Ka- A for acid.1090

That's it.1099

It's called the acid dissociation constant; and there is a list of acid dissociation constants for the different weak acids: hydrofluoric acid, phosphoric acid, nitrous acid- whatever it is.1102

OK.1124

In this particular case, the Ka for hydrofluoric acid happens to be 7.2 x 10-4.1126

OK, this is very small.1136

That means that this is a tiny number, and this is a big number.1140

What that means is that very little hydrogen fluoride actually dissociates to produce hydrogen ion in solution.1144

Yes, it is an acid, and yes, it does dissociate, and yes, the pH of this solution is going to be less than 7; but it's not going to be altogether that much less than 7.1152

It is a weak acid, not complete dissociation.1163

There is an equilibrium that takes place here.1166

OK.1168

Let's do an example - example 2.1171

Let's do phosphoric acid because that is a very, very important weak acid in biochemistry.1177

Phosphoric acid is H3PO4.1185

Now, when acid dissociate, they dissociate one hydrogen at a time.1188

In this particular case, it's not just going to give up three hydrogens; it's going to give up one hydrogen, then another, then another.1192

There is an equilibrium expression for each dissociation, so for phosphoric acid, what you have is the following.1199

When it dissociates, by the way, we're probably going to end up doing this version of it without explicitly mentioning the water; but it's important to remember that it's water that is actually reacting.1205

So, H+ and H3O+, they're interchangeable, they're the same thing.1217

There is no H+ floating around in a solution freely.1224

What it is, it is an H+ that is attached to a water molecule.1226

So, these are the same thing, this is just a different way of writing it.1230

Here, we write this version of the equation simply to explicitly show that water is acting as the base in this acid-base reaction.1234

H3PO4 dissociates into H+, let me go back to blue so that I'm consistent here...dissociates into H+ + H2PO4-.1244

It has a Ka1, a first dissociation constant.1261

Well, now, H2PO4, that can also dissociate.1266

It has a hydrogen ion that it can give up, and it does so under the appropriate circumstances, and it breaks up into H+ + HPO42-.1271

It has an acid dissociation constant associated with this reaction; it is called the Ka2.1282

Sorry about that.1288

Well, HPO4, there is still a hydrogen ion, so under the appropriate conditions, it too can dissociate to produce H+ and PO43-- a phosphate ion.1289

It, too, has an acid dissociation constant, that's the Ka3.1304

So that's it.1310

Let's go ahead and take a particular reaction as our example, and do a little bit more with it.1312

Let's just go ahead and take the second dissociation of phosphoric acid.1319

Our Ka2 is going to be the concentration of HPO42-, the reactants, times the H+ concentration divided by the H2PO4- concentration.1323

That's it, and in this particular case, the second acid dissociation constant happens to be 1.38 x 10-7- very, very, very small.1339

OK.1351

So, again, let me go ahead and write this out explicitly using water as our other reactant, H+ + HPO42-.1353

In this particular case, the H2PO4, this is acting as the acid because it's the one that's giving up the hydrogen ion.1369

The water is acting as base because it's the one taking the hydrogen ion.1380

OK.1390

Now, there is a certain nomenclature that is used.1391

Anytime you have a particular species, if it's the one giving up, we call that the acid.1396

The thing that it turns into once it has actually given up its hydrogen ion, which is this thing right here, we call it the conjugate base; and what that means in this particular case is because if we were to look at this reaction the other way around, in other words, if we were to start with this, now, what happens is - oops, this is not H+ this is H3O+ because I actually used H2O here - now, what happens is if I started with the HPO42- and one would look at it from the perspective of this going that way, then this is actually going to act as the base and it's going to be H3O+ that is going to act as the acid.1404

This is going to be the proton donor; this is going to be the proton acceptor.1450

Now, acid conjugate base- however, when we're looking at it from this perspective, when this is the reactant and this is the reactant, what's acting as the acid is the H2PO4-; what's acting as the base is the H2O.1455

So again, nomenclature is actually not that important.1471

What's important is that you understand what's giving up the hydrogen, what's taking the hydrogen.1474

The giver is the acid, the taker is the base- that is what's important.1478

OK.1484

And, again, notice, the only thing moving here is the H+.1486

Alright, now, let's talk about weak bases.1491

OK.1498

Let's just say first of all, a base, whether weak or strong, is something that produces hydroxide ion in a solution.1500

Well, a strong base does it directly.1511

Strong base produces OH- directly, and by directly, I mean it just dissociates; and when it dissociates, hydroxide just goes in the solution.1515

An example of that would be potassium hydroxide.1525

When I drop that in the solution, I get K+ and OH- now floating around in the solution.1528

Notice the single arrow, there is no equilibrium here, there is none of this left.1534

When it dissociates, it's all this and it's all that.1538

A weak base produces hydroxide indirectly and here is the reaction.1541

I'm going to use ammonia as our base.1564

Oops, no, we definitely don't want that- these crazy lines that show up here.1567

OK, we have NH3- ammonia.1575

When you take ammonia and you drop it into water, a reaction takes place between the ammonia and the water.1579

I'm going to write the water as HOH, that's my personal way of doing it because it actually makes more sense to me.1585

So, I don't write H2O, I write HOH and you'll see why in a second.1592

In this particular case, an H from the HOH from water, now, water is going to act as the acid; it's going to give up one of its hydrogen ions, and ammonia is going to take it.1597

In this case, water is acting as the acid, this is acting as the base; and what you get is the following: NH4+ + OH-.1611

Again, we've produced hydroxide in this solution; however we've done it indirectly.1621

A weak base is something that actually extracts a hydrogen ion from water to leave a hydroxide behind; that's why I write it as HOH.1627

I don't like writing it as H2O.1637

It's just a personal thing.1638

You can do it anyway you want, but this is the reaction that's taking place- very, very important.1639

The generic reaction is this: any base, B + water goes to BH+ + OH-.1644

This is the generic.1662

OK.1663

In this particular case, my B, my base is NH3- ammonia.1664

It can be anything, any weak base, anything that behaves like this.1667

OK.1673

We can write an equilibrium expression for this.1675

Let me rewrite the expression.1677

We had ammonia + water produces ammonium + hydroxide.1680

OK.1689

There is a way of writing an equilibrium expression for this.1690

It is product NH4+ x OH- / NH3.1693

Water does not show up because water is a liquid.1711

OK.1715

Now, when the base reaction is taking place, we call it Kb.1716

I call it the base association constant, and the reason I call it association constant is that the dissociation constant or just the base constant, is because what's happening is that the base is actually associating with an H to become NH4+.1726

So, base constant, acid constant, what's important is the reaction that takes place.1742

OK, let's go ahead and do an example of another base- example 3.1748

So, pyridine, which looks like this.1755

OK.1763

Pyridine shows up, actually, doesn't really matter.1767

Pyridine is a weak base, and notice, it has a nitrogen.1777

It is going to be a common theme, weak bases are pretty much going to have nitrogen in them.1787

It's a weak base.1791

Let's see what its reaction as a base looks like.1794

OK.1797

So we have our pyridine and actually what I'm going to do it I'm going to write it as pyr.1798

Pyridine plus water is going to be pyridine H+ + OH-.1805

That's it.1817

The Kb for this is going to be the concentration of pyridinium ion times the concentration of hydroxide ion, divided by the concentration of pyridine; and in this particular case, is equal to 1.7 x 10-9.1819

Again, this is a small Kb, that means that the reaction hasn't gone very far forward, that it's mostly this way, that in a pyridine solution, most of it is in this form.1842

There isn't a lot of this; there isn't a lot of this.1856

Now, the pH is still going to be greater than 7 because you've taken water, which is pH7, and you've created this extra hydroxide ion floating around; so the pH is definitely going to go up.1860

In other words, the hydroxide ion concentration went up; that means the hydrogen ion concentration went down, the product still equals 10-14, but now, the concentration of hydroxide is higher ,so the pH is above 7.1875

OK.1887

Now, let's see what we can do.1890

So, again, when you're seeing it from the perspective of an acid, when you're doing the acid reaction, you're going to have something called the Ka.1893

When the particular species that you drop into water behaves as a base, like pyridine or like ammonia, you're going to look at it as a base and you're going to have a Kb.1904

OK.1916

Now, let me write a couple of things here.1918

Let me go to a different page.1921

Now, when a species has an H+ it can give up, it is in its acid form.1925

When it can accept an H+, it is in its base form.1956

So, this whole idea of an acid or base is not absolute.1972

It's not that something is an acid or something is a base, it just depends on how it is behaving.1978

If it's in a particular form where it has a hydrogen to give up and it does give it up, it's behaving as an acid; but if it's the other way around, if it turns around and actually takes a hydrogen ion, then it's acting as a base.1985

The same species can be both; it just depends on your perspective.1997

So, again, in science, we need a particular perspective, we need a point of reference from which to measure something, from which to look at it.2001

That's what we're doing here, but it just depends on what's happening in the particular situation.2009

So for example, NH3, well, ammonia, when it's behaving as ammonia, it's going to behave as a base; but, if I happen to have, let's say some ammonium chloride, salt, NH4Cl and I drop that NH4Cl into water, now, what's happening is that there is a bunch of ammonium floating around in the solution, now, this species is not going to behave as a base.2017

Now, it has that extra hydrogen ion and it's going to actually give it up, now, it's going to behave as an acid.2044

So acid-base behavior is based on behavior.2052

It's not that this particular species is an acid or a base.2055

Acid-base reactions have to do with what's happening, what's giving the H, what's taking the H.2058

In this particular case, this NH3 and this NH4, here is the base form, here is the acidic form.2064

For our purposes, since most of the time we deal with NH3, in the list of equilibrium constant values, we've listed it under the heading of a base simply because we tend to think of it more as a base, but it has an acid version.2069

Hydrogen fluoride, we think of it as an acid, well, it is an acid; but when it's in this form, when it's already lost it and when it's behaving this way, it's actually acting as a base, because in this case, now, it's going to take the hydrogen from something else.2088

For example, if I had a sodium fluoride, salt, and if I took that sodium fluoride and if I dropped it in a solution, now, what I have floating around in the solution is a bunch of sodium ions and fluoride ion.2103

Well, F- doesn't have an H to give up, however, this F- is going to end up reacting with the water in a solution; it's actually going to steal a hydrogen ion from the water.2119

So, in this case, it's going to be acting as a base to turn back into its acid form.2130

So, that's what you want to think of.2136

Two sides of a coin, heads or tails, at any given moment we have to decide which perspective- is it behaving as an acid or is it behaving as a base?2138

It can do both depending on what's happening.2148

Now, can we write, well, actually we just talked about that yes, we can write these the other way.2150

So what's important here is the perspective.2161

When it undergoes this reaction, let's just say HA + H2O goes to H3O+ + A-- this is the acid reaction.2165

That's it.2186

But, if I write it this way, I say A- + H2O goes to HA + OH-- that's the base reaction.2190

Be very clear about the species here.2202

Here, HA, it's behaving as an acid; it's giving up its water to produce hydronium and this other species, the base version of its species.2205

Here, if I take the A and if I drop it into water, what it does is it steals H from the water to produce hydroxide and to produce HA, now, it's acting as a base.2216

It just depends on the perspective.2226

That's what's going on here.2228

OK.2230

Let's see, one final comment, so this idea of Ka and Kb, when a species is behaving as an acid, it has a Ka; when a species is behaving as a base, it has a Kb.2235

Here is a relationship between these two.2253

Ka x Kb = Kw = 10-14.2258

So, let's just use hydrofluoric acid as our example.2267

HF + H2O goes to H3O+ + F-.2272

We said that the Ka here - let me see, let's go back, what did we say Ka if HF was, 7.20 x 10-4, I think...right...7.2 x 10-4...that way - but if I happen to, let's say, take a sodium fluoride, salt, and if I happen to run this reaction, now, because it's acting as a base, if I do any math with it, I have to use the Kb, not the Ka.2286

Well, the Kb happens to equal the Kw over the Ka.2325

Now, I just wanted to introduce it here towards the end.2330

I'm actually going to be discussing more of this in the next lesson, so don't feel like this just..."Wait a minute, what's going on here?2332

I am going to be beginning the next lesson with the discussion of Ka, Kb and the relationship between those two; and we'll do some more problems.2340

Until then, thank you for joining us here at Educator.com.2348

Take care, bye-bye.2350

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