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For more information, please see full course syllabus of Biology
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Lecture Comments (24)

1 answer

Last reply by: Bryan Cardella
Sun Jan 29, 2017 3:44 PM

Post by Kapil Patel on January 28, 2017

Hi Mr. Cardella can you help me with the pH Practice problems 1. If I have a solution with a pH of 4, what is the hydrogen ion concentration ([H+]), hydroxide concentration ([OH-]) and pOH?

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

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

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

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

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

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

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

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

1 answer

Last reply by: Bryan Cardella
Tue Jun 9, 2015 4:23 PM

Post by Aymane Mousa on June 7, 2015

Why cant i open these classes with my iPad. With laptop i can but not ipas

3 answers

Last reply by: Bryan Cardella
Sun Jan 25, 2015 2:04 PM

Post by antonio cooper on January 24, 2015

So could someone just verify if I am understanding this correctly.
-Monosaccharides are also called monomor and if you have more than 1 monomor you have a polymer.
-If you have 2 monomor which is also 2 Monosaccharides it is a disaccharide.
-If you have more than 2 monomore (>2 Monosaccharides) you have a polysaccharide.

1 answer

Last reply by: Bryan Cardella
Tue Oct 7, 2014 10:19 AM

Post by Jamal Tischler on October 7, 2014

Doesn't the lithium atom have 4 neutrons ? It has the atomic number 7. Thank you ! I realy liked the lesson.

8 answers

Last reply by: Bryan Cardella
Tue Nov 4, 2014 3:17 PM

Post by Yong yi Ji on September 9, 2014

where i can find the question related to this leature

1 answer

Last reply by: Bryan Cardella
Fri Jul 11, 2014 6:45 PM

Post by Brady Dill on July 11, 2014

It's not a Latin letter. It's Greek. Lowercase Delta.

1 answer

Last reply by: Bryan Cardella
Tue May 27, 2014 9:59 AM

Post by abdisalam aynte on May 26, 2014

i have a lot of buffering and lessons stops when ever i start or repeat so is it my internet or the wepsite.

0 answers

Post by Matthew Teuschel on March 15, 2014

Great lesson. Enjoyed your enthusiasm.

Molecular Basis of Biology

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
  • Building Blocks of Matter 0:06
    • Matter
    • Mass
    • Atom
    • Ions
    • Bonds
  • Molecules 9:55
    • Ionic Bonds
    • Covalent Bonds
    • Water
  • Organic Compounds 17:48
    • Carbohydrates
    • Lipids
    • Proteins
    • Nucleic Acids
  • Carbohydrates 22:54
    • Sugars
    • Functions
    • Molecular Representation Formula
    • Examples
  • Lipids 28:44
    • Fats
    • Triglycerides
    • Functions
    • Steroids
    • Saturated Fats
    • Unsaturated Fats
  • Proteins 37:26
    • Amino Acids
    • 3D Structure Relates to Their Function
    • Structural Proteins vs Globular Proteins
    • Functions
  • Nucleic Acids 42:53
    • Nucleotides
    • DNA and RNA
    • Functions

Transcription: Molecular Basis of Biology

Hi, welcome back to, this is the molecular basis of Biology.0000

If we are going to talk about Biology and the parts that make up living beings.0007

We have to get to what are the parts that make up the parts because it goes from small to big.0011

It is hard to understand everything that is happening microscopically on the surface,0018

if you do not know what is making it all happen in the smallest bits.0022

With the building blocks of matter, this really applies to every science, especially Physics, matter.0027

Matter is anything that has mass that takes up space.0034

Basically, the only thing that is not matter is space.0037

I do not mean just like outer space, I mean space being the lack of substance,0042

the lack of something physically being there.0047

If you were to talk to a physicist, they might give you a more advanced version of this.0051

They might tell you something about anti-matter, dark matter, or whatever it might be.0056

For our purposes in Biology, just knowing that matter is anything that has a measurable mass, substance, and takes some space, is matter.0060

What is mass? Mass is a measure or measurement of how much matter of something has.0070

Mass is the preferable way of actually measuring the amount of matter in a structure, in a living being, rather than weight.0076

Weight, something that has been used in America, is mass times the force of gravity, to get that measurement.0084

If you look at the International Science community, mass is used in terms of grams, kilograms, etc.0093

If you have more mass, you have more matter.0102

The atom, the atom is the smallest functional unit of an element.0107

The elements, when you look at periodic table of the elements from Hydrogen to Uranium,0111

those 92 elements being all the ones that are naturally found on earth.0116

93 through 100 and whatever, those were synthetic.0120

Those were put together in the lab, they may have existed just for a short period of time.0124

But scientists, they combined atoms to make them exist.0130

In terms of all the elements you would find in living beings, when we look at the smallest bit of that element,0135

like the smallest bit of carbon, the smallest bit of oxygen, it is an atom.0142

If it is smaller than an atom, if it is just like a single electron, you cannot call it an oxygen electron.0147

They have come from an oxygen or may have come from a carbon,0155

but for you to call it that piece an element, it has to be the whole atom.0159

You will see what that means in a second.0165

Proton, let us use red to represent the protons, these are positively charged subatomic particles.0166

Inside of an atom, they tend to be in the center, in something called the nucleus with what are known as neutrons.0181

In parenthesis, I want to put a 0 because neutron for neutral, they do not have a charge.0188

There we have our nucleus, it is in the center of an atom, it is positively charged because of the protons.0199

The number of protons influences the element.0204

Since I drew 3 protons here, this is a lithium atom.0207

If I put another proton to make it 4, it will be Beryllium.0212

Another one to make it 5, it would be Boron.0217

If you have 6, it will be Carbon.0219

The number of protons makes the atom whatever element it is.0221

The number of neutrons influences the mass.0225

If you add neutrons, you are not affecting the charge but you are affecting the amount of matter0228

that is inside of that atom and that can affect how the atom behaves.0235

Electron, these are spinning around the outside and they are negatively charged.0241

I am going to draw 3 electrons out here.0250

I am not going to do the rings that you tend to see in the Bore atom or bore model of an atom, or in other models.0255

The track that you tend to see the electrons on, in that typical looking atom drawing, is not realistic.0265

It is not like they are spinning around a racetrack and they are confined to that path.0272

They tend to exist in little orbitals or little electron clouds.0275

At any given moment, they can be in any part of that cloud.0280

This one could actually be here or this one could be here, this one could be here.0283

Because of the space we have in this particular slide,0287

I cannot give you a realistic depiction of how far the electrons are from the nucleus in the center.0291

But the analogy that I have heard to give you a good sense of it is,0296

if you had a bumble bee in the middle of a football stadium or baseball stadium, whatever it might be,0300

the bumblebee is the nucleus and the edge of the stadium or arena is the nearest electrons.0308

That is how much space is usually between the outside of the nucleus and the closest electrons, which is crazy to think about.0314

Which is why there is a crazy fact that everything that has matter is still mostly space0321

is because of the amount of space in every individual atom.0329

That is kind of creepy to think about.0331

Here is your atom, right now it is neutral.0333

We have an even amount of negatively charged electrons and even amount of protons.0337

This has no net charge, meaning the amount of positives equally to negatives, so that charge is 0.0340

But an ion, let us do this black, this is a charged atom and it could be a positive or negative.0348

A cation is positively charged and anion is negatively charge.0366

Basically, it has to do with either the addition of electrons or the subtraction of electrons then leaving the atom.0380

Like I said before, if you change the number of protons, you have changed the element.0387

Ions have to do with, like charged atoms of any given elements.0391

Let us say, we had a sodium atom, the symbol on a periodic table is Na for sodium, the S is taken by sulfur, so they use Na.0394

Sodium actually loves to make a +1 charge, a lot of times you will see Na⁺.0411

The reason why is, when you count the number of protons for Sodium, it is 11.0418

The number of electrons, when it is neutral would also be 11.0423

But it turns out, one of the electrons on the outer most valance shell, the outermost part of the atom really likes to leave.0426

The atom does not mind it having its electron leave and go with another atom to make a bond.0438

And when that one electron, that one negative charge leaves, if you would add the number of protons which is now 110444

and the number of negatives electron which is now 10, you would then now have a +1 charge.0450

This is the ion you tend to see with sodium.0456

Conversely with chlorine, chlorine tends to make an anion, a -1 charge.0459

Sometimes, you will see a little one there but a lot of times you will Cl⁻.0466

Why does it do that? Chlorine loves to take on one additional electron to fill its outer shell0474

and it feels atomically satisfied, if you want to of it that way.0480

It turns out that these two would love to get together because sodium would like to give up its electron0485

to make the + charge and this one would like to take on one.0491

A lot of times, you will see Na and Cl combining, and sodium chloride is salt, when they get together.0494

They love to make NaCl which is also known as table salt.0501

When it comes to bonds, meaning atoms actually getting together and0508

having their electrons behave in way that keep something together,0512

two of the main ones you will see in this particular course are ionic bonds and covalent bonds.0515

Ionic bond is the transfer of electrons from one to the other.0520

I am writing e- to symbolize electron, I will have a little blue circle.0530

Covalent bonds, a little bit different, this is the sharing of electrons.0537

Sometimes they shared unequally, we will get to that in a little bit.0547

Ionic tends to be between metals and nonmetals.0553

It turns out that sodium is on the left hand side of the periodic table.0557

Metals make this positive charge, they tend to make cations.0562

Nonmetals on the far right hand side of the periodic table.0566

Not the very last column, that is the noble gas, but right next to there you see nonmetals.0571

When these two get together, it is perfect, it is a transfer of electrons from the metal to the nonmetal,0577

and then you have an ionic bond that keeps them attached.0583

Covalent tends to be between nonmetals and it is when they share electrons.0587

Like I said, it could be equal sharing, it could be unequal sharing.0592

Ionic bonds hold together metal and nonmetal.0597

The metals they make the plus charge, nonmetals make a negative charge.0603

Like just I wrote on the previous slide, NaCl normally this makes a +1, this makes a -1, perfect,0610

they go together.0619

They each have what the other one wants or needs, in a sense.0621

Magnesium sulfide, magnesium actually makes a +2 charge and sulfur makes a -2,0625

they get together in the same way.0632

If you had Magnesium chloride, you would actually need 2 chlorides to bond to make it neutral.0636

When you see the ionic bond holding the other metal and nonmetal,0644

they typically as a compound or as a molecule, they tend to be neutral.0649

If we had magnesium chloride, you would actually see it as MgCl₂0655

because the two negatives would then neutralize with the +2 for magnesium.0664

Covalent bonds typically hold together nonmetal and nonmetal.0670

Here, we have classic gas, in this particular course, carbon dioxide CO₂.0674

The way that you will see teachers write it out, in terms of how the bonding happens is like this.0680

These lines here, this means a double bond, meaning between this carbon atom and this oxygen atom,0688

you have electrons shared here and here.0695

On the other side, between carbon here and here.0699

Carbon likes to make 4 bonds, that is what it does, and that is the key to organic compounds which is coming up in a future slide.0702

This is a covalent bond holding together the carbon with the 2 oxygens.0710

With oxygen, O₂ gas, it would be like that.0715

With both of these, you have an equal sharing, they call this a nonpolar covalent bond.0723

At any given moment, you would see an equal sharing of electrons with the carbon and the oxygen and same here.0730

It is not sort of lopsided, in terms of like one side being slightly more negative0740

because it is hugging the electrons a little more than the other side where it is slightly more positive.0744

But when it comes to water, the covalent bond that exists with the water is very interesting.0749

This is the key to life on this planet.0754

Water is the key to every living being coming into existence.0757

For the vast majority of species, water needs to be inside of them and needs to be something that is replenished, if lost.0763

They need it for chemical reactions, there is so many important purposes for water.0772

Later on in this course, I will give you a few examples of living beings0777

that can go even a decade without water, which is pretty crazy but that is rare.0780

When you look at the water molecule, polar covalent bonds hold 1 molecule together.0787

If we looked at one single water molecule, let me draw it in here.0792

That is kind of the angle that you tend to see with 1 water molecule,0803

it is not just a kind of straight cross like this one, in terms of the atoms being bonded.0807

Here is the H₂O and this right here, that line and that line, these are these polar covalent bonds.0811

The reason why it is polar is because it is unequal sharing.0820

I am going to draw a little arrow towards the oxygen because it turns out the oxygen0824

is hugging the electrons a little bit more than it is giving to the H.0830

I had a professor that drew this way which help me remember it.0835

These little arrows are too full, did you see the arrows are pointing at the oxygen0839

meaning they are hugging the electrons more.0844

Down here, if you draw this little perpendicular line and the arrow, it looks like a positive sign.0846

That positive is at the H end.0851

This side of the molecule and this side, they are positively charged.0854

Up here is negative and if you are wondering why did I drew that,0862

that is a Latin letter that is associated with charge designations on these molecule.0867

This is just a fancy way to say, this side of the molecule more negatively charged.0873

This side of the molecule and this side of molecule more positively charge.0877

When you look at how individual water molecules bond to one another, hydrogen bond pulls together neighboring ones.0882

It is not actually covalent or ionic, in a sense.0887

Let me explain how that works.0891

I am going to use a dotted green line for the hydrogen bonds.0896

What you would see is, attraction of the oxygen of 1, which is more negatively charged to the hydrogen of another.0903

Conversely, you would see this, you would see here is an oxygen of another water molecule.0921

You would see the H of that water molecule be attracted to the O of the neighboring one.0930

This is how it works with hydrogen bonding.0937

The positive side of one molecule settles up next to the negative side of the other.0940

This is a very polar substance.0944

Water is polar because you do not have even distribution of charge.0947

That has a lot to do with the dissolving of salts or ionically bonded compounds in water.0951

When you put NaCl in water, the Na tends to be the positive charge and the chlorine, the Cl tends to be the negative.0959

They tend to be distributed in a way where, they kind of get next to the0967

positive and negative parts of they are attracted to, between water.0970

It actually helps dissolve a lot of things in nature.0974

You could see that this hydrogen bond holds together these neighboring water molecules.0977

The difference between solid water, liquid water, and gaseous water, comes down to this.0982

Solid water that is of course ice, frozen ice, which is redundant to say.0987

Solid water or ice has consistent maintain hydrogen bonds.0995

If you picture out that my torso is a single water molecule and my arms are bonds,1002

they are just literally frozen in that bonding.1007

That is ice right? Solid, it is just sitting there in its solid form1011

But as you apply temperature, these bonds will break and reform.1017

Liquid takes the shape of whatever container it is in, liquid water.1022

If I put it in a container that is cubed shaped, well the liquid looks cubed.1028

If I put it in a very long trough-like container, the liquid will take that shape.1033

It is because with liquid water, these hydrogen bonds between the water molecules1038

would break and reform, break and reform, break and reform.1042

Then, when you heat that a bit more, you heat up that liquid water to get to be vapor, gaseous water,1045

you see these bonds just completely break and the water molecules just go nuts, leaving the liquid and entering as gaseous water vapor.1052

And that comes down to hydrogen bonding and the differences between the solid, the liquid, and the gaseous phase.1062

When we look at organic compounds, these are really the building blocks of cells1069

which is what life is and in terms of how it exists in this planet.1075

Life is made of cells, and therefore main organic compounds, the first is carbohydrates.1079

Here is a model of linear carbohydrate.1087

This is glucose and if you count the carbons 1, 2, 3, 4, 5, 6,1090

it is a very common case with carbohydrates to have a 6 carbon sugar.1095

You will also see ones of that has 12 carbons.1102

You will see ones that have 24, and so on.1104

When we look at something like starch or glycogen which are huge carbohydrates,1108

you could have hundreds or thousands of carbons because it is a big, big sugar.1113

You could see on either side, except for this top part, you got H and OH, OH and H, H and OH.1117

If you think about what would H and OH make, when you put them together,1123

we just had that on the previous slide, water.1127

The term carbo—hydrate, carbohydrate, the name makes sense.1130

You also see this occasionally in the ring form, there will be an oxygen there.1136

At each corner is a carbon and you will see another carbon here H₂OH.1142

This will make more sense on the next slide, when I talk about carbohydrates in detail.1150

Each one of these corners is one of these carbons, this line, that line, these sides,1156

these are the bonds between the carbons.1162

Off of each corner, you would see an H and an OH just like here.1165

There are different ways of depicting these carbohydrates.1174

This one shows you every single atom, in terms of the carbons, hydrogen and oxygens.1177

Lipids also made of carbon, hydrogen and oxygen, have a different purpose.1183

Per gram, if you compare carbohydrates and lipids, these actually have more energy stored up in them,1190

in terms of you break down a lipid, how much ATP, which is an energy molecule can you get of it, you can get a lot.1197

This is another way of depicting it, each one of these corners is a carbon atom.1204

The lines here are the bonds between the carbons.1209

Attached to every single carbon, other than the neighboring carbons, you would see hydrogens here.1213

Often times, we will call this a Hydrocarbon chain, it is also known as a fatty acid chain.1218

Right here, this double line, that double line, those are double bonds1225

like we saw between oxygen atoms on the previous slide.1228

The double bonds in lipids create a kink, a little bend in this chain, that can affect the lipid which we will see in a little bit.1233

Moving on, we got proteins, a huge deal in this class, in terms of making a cell, what it is.1243

The different cells in human body, they have the same DNA but1250

it is a matter of which DNA is being expressed to make that cell differentiated,1255

to make that cell have a purpose or function in that tissue.1259

It is a matter of what proteins are in its cell membrane and what kinds of enzymes are inside of it,1263

what structural proteins are there.1269

This is a three dimensional molecule of what a protein is made up of.1271

I know you cannot see the c’s, the H’s and the O’s here.1274

Also with proteins, you will also see nitrogen and you do also see sulfur, as well.1279

But definitely, carbon, hydrogen, oxygen and nitrogen, common in proteins, they are necessary for it to be a protein.1287

What you are seeing here is kind of zoomed out compared to the other two on the previous slide.1295

This particular red ribbon, this is known as a α helix.1302

It is a sequence of amino acids which is building blocks of proteins that are strung together in a helical shape like how our DNA is.1307

But, you will also see what are called pleated sheets.1317

You could also see other, this green ones or another kind of amino acid chain.1321

You really have a much bigger molecule, much bigger than what we saw on the previous two,1327

with carbohydrate and lipid.1333

This has a very specific function, in terms of what it is doing, and that is based on these three dimensional shape.1335

Nucleic acids, that is DNA and RNA.1341

Here we see that classic double helix of DNA.1343

Right now, in this image, it is being replicated.1347

Both sides of the DNA are each being copied, a copy of each strand is being made with respect to each side.1350

This is what needs to happen in a cell, before it divides, before it makes what are called two daughter cells.1357

It is the way of passing on the genetic information accurately and correctly to both daughter cells.1363

We will see much more about nucleic acids later on in this course.1370

When you look at carbohydrates in detail, these are also known as sugars.1376

It is not always digestible sugar though, you will see that with nutrition facts.1381

There are sugars like glucose which you use for energy every time you eat something sweet.1386

Chances are, there are some glucose in there but there are other sugars known as fibers, dietary fiber,1392

that you and I do not digest, we do not actually break it down and absorb it.1398

It just runs through your intestines like kind of a drain cleaner almost, and helps keep you regular.1404

There are other organisms like cows, giraffes, antelope, that do break those down and1410

thanks to a certain bacteria in their gut, we will get to that later.1416

These are also known as sugars.1420

Functions, the primary function, energy source, without a doubt, that is what glucose is meant to do.1422

Plants make glucose to the process of photosynthesis and all life depends on that.1430

Whether you are herbivore, an animal that only eats plant material, or omnivore it only eats and meat, or carnivore eating just meat.1436

The animal does depend on the making of glucose because even something like a tiger that eats just flesh.1446

Let us say it is an antelope, how did the antelope nourish itself, it got glucose from the plants it ate.1456

Energy source is the primary function of carbohydrates.1463

Energy storage, in plants, it is known as starch, in terms of putting a bunch of glucose, a bunch of sugar,1466

tends to make a big storage molecule.1476

Something like a potato, it is very high in starch.1479

Another one, in animals is glycogen.1484

This is in a sense, animals starch.1489

If you and I eat too much sugar, it is possible that it can be stored as fat.1492

You do store away glycogen in your liver and muscle cells, primarily, as a way to have a reserve of sugar.1498

If you go on a long run and it is been two or three hours since you have eaten,1505

your liver will be stimulated and your muscles will be stimulated to break apart glycogen.1511

This can make a thousands of glucose molecules.1515

It is broken apart, that glucose is given to your muscles and your cells that need that energy.1518

It is been awhile since you have actually consumed glucose.1525

Whether it is plants or animals, energy source is important.1529

Structural purposes, two examples.1532

In plant cell walls, cellulose is a structural carbohydrate.1535

Cellulose is the main ingredient of plant cell walls.1545

Plants are not using that to break it down and get energy, they are using it to keep their cell walls rigid and protected.1547

Another one is Chitin, that is a terrible arrow.1557

Some people pronounced it chitin but I was told that is called chitin.1564

Chitin is in fungal cell walls, like a mushroom cell wall is made of chitin and1568

the exoskeleton of arthropods, of insects, like beetles hard outer body shell is made of chitin.1573

That beetle is not consuming its own body shell for an energy source, there is a structural protective purpose.1582

These are both called polysaccharide, a very large sugar molecules.1590

Here is the basic kind of molecular representation of what kinds of atoms are in carbohydrates, in terms of the typical ratio.1595

N means any positive integer can you put in there, any number from 1 on up.1604

If you put 6 in here and a 6 in here, that give you glucose.1613

You have 6 carbons with 6 water molecules, carbohydrate is perfect name.1617

If I put a thousand here and a thousand there, you are probably looking at1624

something like glycogen or starch, or a very large sugar.1628

Monosaccharide, these are simple sugars, tiny sugars, they call them a monomer.1633

With all these organic compounds, a monomer is one building block.1641

You put together a bunch of monomers and you eventually get what is called a polymer.1648

The monomer for carbohydrates is monosaccharide.1655

This would be glucose, another one is galactose, and there is fructose, there is a lot of them.1658

Both of these are simple single sugars.1668

You put together two monosaccharides, you get a disaccharide, di mean double or two.1670

Sucrose and maltose, the way we get in this, if I put together a glucose and a fructose,1678

that gives me a sucrose.1691

If I put together glucose and a glucose, that gives me a maltose.1692

Sucrose is also known as table sugar, that white stuff that is used for baking.1696

Maltose, malt sugar.1703

Polysaccharides, I mention them up here.1706

Here they are, I have to write them again, starch, glycogen, cellulose, chitin.1709

These are all polysaccharides, hundreds, sometimes even thousands of these monosaccharide1713

put together to make a very large sugar.1720

Lipids are the next one also known as fats.1725

I know in our society, these have a bad reputation but they are needed, as a part of a healthy diet.1728

You need them, if you do not get any fat that can lead to some negative health problems depending on your fitness level.1735

Triglyceride is kind like a classic lipid, you tend to hear most about with nutrition and with this particular course.1743

Triglycerides, that comes from putting a glycerol with three fatty acid chain.1751

There is the tri, the glycer, you can see how that name came together.1757

Glycerol looks like this.1763

And then here, everyone on the blanks, everything that I have right written that is just an H, a hydrogen atom.1778

Like I have said before, carbon really likes to make 4 bonds, that is what it is good at doing,1785

you can count here, they each make 4 bonds that surround them.1793

This, by itself is a glycerol but still you need the 3 fatty acid chains.1797

They are attached here, this three spots.1802

What actually needs to happen is, it is called the dehydration reaction.1805

That is what actually need to happen in the previous slide, if you want to attach two monomers together,1809

if you want to attach glucose to glucose.1814

H and OH leave off on each molecule and then you have them attached.1817

We are going to see that here, because this can be very long.1821

Here you have a carbon, there is an OH hydroxyl that is a double bond with the oxygen,1837

this is that hydrocarbon chain.1843

What actually leaves is this and this, and when H and OH leave together, it is water.1845

That is why they called it the dehydration reaction.1853

There goes water, it went bye-bye and then this can attach.1856

Let me move that up and bond it here.1862

Here is that hydrocarbon chain and it can be very long.1871

I am not going to draw all the hydrogen but every single bond here has a hydrogen attached to it.1873

This could be really long depending on the length and the actual amount of atoms that are attached here,1881

that determines the different name for this fatty acid chain, there are a lot of different ones.1890

The same thing would happen on down the line here to make a full triglyceride.1896

In a moment, I will tell you about what that double bond does.1905

If you remember about how carbon likes to make 4 bonds, if there are two bonds here that means1915

there is going to be one less hydrogen attached because 1, 2, 3, 4.1923

I will finish drawing that in a second.1927

But back to functions, what is this thing do? Why is it important?1929

It can also be broken down as energy source.1933

Like I have mentioned earlier, you actually can get more energy out of a gram of lipid than a gram of sugar.1937

It is a great energy source.1944

Insulation, there is a layer of fat primarily between the lower levels of your skin,1946

and the muscles you have, the skeleton muscle you have.1953

That is your adipose tissue layer, that helps keep you warm.1956

Also in terms of what surrounding your organs and what is helping to keep bloody organs in place,1961

there are insulatory layers of fat in your body that you are not even aware of.1967

Hormones synthesis, this is one of the dangers of having 0 intake of fat.1971

Some people who have no fat intake and are bringing too much fat in their physical activity,1977

they can actually stop making certain hormones.1983

For instance, estrogen is a hormone that is made from lipids, it is synthesized from fat.1986

Some women who were extremely athletic, who are not getting enough fat in their diet,1993

they can actually stop going to their cycle normally because they are not producing enough estrogen,1999

since they are not taking in enough lipids.2003

And of course membrane synthesis, every membrane of every one of your cells is known as a phospholipid bilayer.2005

The keeping up with your membrane structure and rebuilding it when needed, you need lipids to do that.2014

Steroids, steroids have a bad reputation on our society.2021

But here, I am not necessarily talking about anabolic steroids that some athletes had abused.2025

It is not just that, steroids are naturally found on your body, it is a lipid based signal molecule.2030

Sometimes it comes in the form of a hormone, something like testosterone or estrogen is known as a steroid hormone.2037

This tends to have a different shapeness, you actually would see kind of these hexagonal pieces,2046

in terms of how the steroid is built, but it is lipid based.2053

And then finally, what are saturated fats versus unsaturated fats?2058

Saturated fats, they tend to be solid at room temperature, solid at let us say 20° C,2061

and these tend to be liquid at 22° C or 20° C, why is that?2082

Saturated fats which tend to come more from animal tissues, red meat, any meat that you would consume,2093

tends to be higher in saturated fat because when you look at how saturated fat is built, you actually do not see any double bonds.2101

There are no double bonds here and what is happening is, this hydrocarbon chain is straight out,2109

this hydrocarbon chain straight out, and this is straight, you will not see the kinks like I drew here.2114

Because the fatty acids chains all layout straight, they can be compacted very close together,2119

they can be densely compacted when they are altogether and that tends to form a solid mass.2127

Something like butter, a stick of butter it room temperature is high in saturated fat.2132

You can melt it, but saturated fats no double bonds between these carbons and they tend to exist in little dense packages.2137

The reason why they are slightly more unhealthy is because a diet high in saturated fats means that2148

you are more likely to get a clogging of the arteries with these solid clumps of fat, compared to the liquid versions of them.2155

Moderation is key, in terms of consuming saturated fats.2164

Unsaturated fats, the reason why they are in liquid or room temperature,2167

tends to be because these double bonds, you would see in unsaturated fat, these have the double bonds.2171

We have double bonds which make little kinks.2185

Imagine, having a bunch of papers that you crumble up and you tried to put them in a nice and neat little stack,2187

if I crumble them up, they do not sit together very nicely and close together.2193

That makes them more liquidly, they do not get dense, they compacted quite the way with the saturated fats do.2200

Olive oil, canola oil, vegetable oil, in general, these tend to come from plants more so than animals.2209

Diet that is higher on saturated fats versus unsaturated fats, you are less likely to develop a sclerosis.2218

A narrowing of the arteries and making the pathway that blood flows through those arteries more narrow,2225

which can lead to heart disease, which can lead to a heart attack.2233

Moderation, in terms of consuming fats and being particular about how much saturated fat2238

you are consuming versus unsaturated fat is important.2243

Proteins, these are arguably one of the more important organic compounds.2248

They are all important of course, but In terms of what makes a cell a cell, in terms of what type of cell it is,2253

what organism it is, in terms of how it is being expressed, that comes down to the proteins that are produced.2262

The variety of proteins compared to another cell.2269

You would not get these without nucleic acid that is why we cannot leave out the other ones.2273

Proteins are made of amino acids, that is the term monomer before.2278

Amino acids are the monomer for the polymer that we would call a protein.2283

A chain of amino acid, an amino acid chain is known as a polypeptide.2294

Here is that poly for polymer and peptide, the bond that exists between neighboring amino acids.2299

Imagine that you to each of my fists is the amino acid, the pen here that is a peptide bond.2304

The reason why polypeptide is perfect is, a chain of them, you will have all those peptide bonds.2310

Going back to the previous lesson, on our previous slide on bonds, this would be a covalent bond.2317

All the particular bonds we looked at with, with inside of carbohydrates, lipids and these,2325

they are types of covalent bonds.2330

They are three dimensional structure relates to their function.2333

For instance, this right here computer generated image of the different amino acid chains2336

and how they are structurally held together in this pattern, this is hemoglobin.2341

This is how your red blood cells are able to function, in terms of transporting oxygen around your body within your bloodstream.2346

These three dimensional structure allows it to have a high affinity meaning attraction for oxygen molecules binding here.2353

If some of the amino acids are wrong, in terms of how they are put in here2362

and how they are attached, the shape of the protein changes.2367

The protein will not be affected like what it is supposed to do.2371

That particular amino acid error can be related to a mutation in DNA, we will get to that more later.2375

But this brings you to the next point, structural proteins vs. Globular proteins.2381

This is a globular protein, this protein has a metabolic function in terms of transporting oxygen to cells that need it.2385

Structural proteins, a little bit different, something like when you looked at collagen for instance.2396

Collagen is a structural protein, it is really the most abundant protein found in human body.2403

Collagen, you would find in bones, joints, in terms of how ligaments and tendons exist.2409

That has a structural purpose, in terms of holding stuff together in your body.2416

Globular proteins tend to things like an enzyme, has some kind of catalyst function.2422

That is something that we will get to in the future lesson.2431

Enzymes are kinds of proteins that help a metabolic process occur,2432

it helps it along and make it easier to happen in the body.2437

Functions, I hinted some of them but signaling is one.2441

A lot of the hormones in your body are protein based.2445

Also neighboring cells can signal each other, in terms of saying like I am this kind of cell,2449

I want this kind of cell, based on proteins being sensed.2454

Movement, muscles is a classic way to think of that.2459

Your muscle cells would not be what they are without proteins.2464

Myosin, actin, if you look at the physiology lessons on,2469

you will see that muscles will not be able to contract and relax without proteins moving, with respect one another.2475

Hormone synthesis, mentioned that previously.2483

A hormone like epinephrine better known as adrenaline would not exist without proteins.2485

Enzymes, mentioned those previously, whether it is something like amylase,2490

that was mentioned in the previous lesson, the first lesson for this course.2494

Or something like catalase, enzymes tend to end in ASE.2500

There are so many enzymes in the human body and in every organism.2508

These make reactions happen a little bit more easily.2512

They can build up a molecule, they can break down a molecule, depends on the enzyme.2515

Protection, antibodies, you would not be able to make antibodies to help immune response without proteins.2520

Storage, when you look at the structure of an egg, in terms of how the egg is separated in different parts,2530

the yolk, the albumin, etc, proteins can contribute to the storing of organic compounds in a cells and energy source.2537

You can actually break down a protein to get energy within a cell.2547

It is not as common as using sugars or fats on a cell but if proteins are rather available,2551

you can strip off a part of the amino acid that contains the nitrogen in it,2559

and you can do a conversion to make the protein kind of more reminiscent of that carbohydrate structure or lipid structure.2563

You can use them for energy.2571

Finally nucleic acids, without nucleic acids you would not be able to make proteins,2575

and cells would not have instructions in terms of how to do what they do.2580

Nucleic acids are made of a sequence of nucleotides.2585

Once again, the nucleotide these are the monomers.2587

Something like a whole DNA molecule that would be the polymer, a bunch of this nucleotide strung together.2596

A nucleotide is a phosphate, sugar, and base.2601

You are going to see this in a greater detail in a future lesson.2605

What I am drawing here is a very simplistic representation of the phosphate which is phosphorus with oxygen.2613

The sugar which, if it is DNA is called deoxyribose, if it is RNA it is called ribose.2620

It is a 5 sided pentose sugar and then a base, the different bases, that nitrogenous bases, whether they are A’s G’s C’s or t’s.2626

You may have heard of these before, these makeup the genetic code,2635

in terms of the sequence of them in the polymer of DNA or RNA.2638

I have a little jingle that I made up to remember what is in the nucleotide of DNA or RNA.2644

To jingle it, it is phosphate sugar base, your DNA determines your face, and it is true.2651

It rhymes to help you remember it, you can think of it as a country song and be like,2658

phosphate sugar base, your DNA determines your face.2663

Whatever works but that is how I remember it.2671

DNA and RNA, whether it is deoxyribose or ribose means2674

whether or not, it is going to be deoxyribonucleic acid which is the full name for this, or ribonucleic acid.2680

In the lesson on how DNA actually is made into protein,2686

you are going to hear a lot more about the structural purposes of DNA and RNA, how they have a functionality?2691

In terms of making this information in DNA work, how it is actually end up making proteins in a cell?2698

It does store genetic information and it transmits that code for the purposes of making protein.2706

This code is passed on from generation to generation.2711

Overtime, over the eons, it does change.2715

Mutations, a lot of times they are bad, in terms of these bases being changed to DNA.2719

But mutations can be a good thing, that is the key to evolution which we will talk about in future lesson.2724

If you are wondering what the heck is this, this is a type of RNA called (tRNA) transfer RNA.2730

There are several kinds of tRNA, the letter or letters in front of RNA tell you what kind it is specifically.2738

This is a really cool computer generated image of, you can see this single stranded,2746

you can trace the RNA down although it is folded up,2753

RNA polymer but has a very specific structure, a three dimensional structure.2756

On the bottom here is something call an anti-codon, up to the top you have an amino acid there.2761

This is an easy way to think about it, actually when I picture tRNA’s, I picture this.2766

It looks like a T and this actually participate in putting together amino acids, it is something called a ribosome.2772

These are very important, without these, you are not going to get2781

the building of a protein and cells would not exist as they do in nature.2785

Thank you for watching