Download 1/23 Notes and Classwork

MACROMOLECULES
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Macro means LARGE
Molecules are groups of atoms (and an atom is a single piece of something, such as carbon or
oxygen)
We're getting into some chemistry here, which is tough since you haven't had chemistry yet...but what is
important to remember is that the bonds that hold the atoms together hold tremendous amounts of
energy.
This is the chart that we made to describe the structure and function of the major organic molecules
(organic means that they have carbon in them!)
Nucleic Acid
Protein
Lipid
What is it made
of?
Chains of base
pairs (A, T, C, G,
U)
Chains of amino
acids
Carbon atoms (in a Carbon atoms (in a
chain)
ring)
What does it do?
Contain
Runs our bodies
instructions for our functions
cells
Protection
stores energy
Draw or Describe Ribose (sugar)
attached to a
phosphate and a
nucleotide
Chain of amino
C-C-C-C-C-OH
acids → folded up
and twisted around
Give an example
Hemoglobin (in
your blood)
DNA, RNA,
tRNA, mRNA
Carbohydrate
Provides/stores
energy
C-C
C
C
C
C
C
(they all should be
connected by lines)
earwax
glucose
Lipids
Lipids are another type of organic molecule. Remember that organic means they contain
carbon (C) atoms. It's not like organic farming at all. When you think of fats, you should know
that they are lipids. Lipids are also used to make steroids and waxes. So, if you pick out some
earwax and smell it, that's a lipid, too!
Get the Wax Out of Your Ears
Waxes are used to coat and protect things in nature. Bees make wax. It can be used for
structures, such as the bees' honeycombs. Your ears make wax. It is used to protect the inside of
your ear. Plants use wax to stop evaporation of water from their leaves. There is a compound
called cutin that you can find in the plant cuticle covering the surface of leaves. It helps to seal
and protect plant structures. Don't worry about plants being able to breathe. There are still
small holes that let gases in and out of the leaves.
Steroids
Steroids are found in animals within something called hormones. The basis of a steroid
molecule is a four-ring structure: one ring with five carbons and three rings with six carbons.
You may have heard of steroids in the news. Many bodybuilders and athletes have used
anabolic steroids to build muscle mass. The steroids make their bodies add more muscle than
they would normally be able to. Those anabolic steroids help bodybuilders wind up stronger
and bulkier (but not faster). Steroids are also used in necessary medicines. Some help people
with acne, while others are used as muscle relaxers for injuries.
NOTE: Never take drugs to enhance your body. Those athletes are actually hurting their
bodies. They can't see it, because it is slowly destroying their internal organs and not the
muscles. When they get older, they can have kidney and liver problems. Some even die.
Triglycerides
Fat is also known as a triglyceride. It is made up of a molecule known as glycerol that is
connected to one, two, or three fatty acids. Glycerol is the basis of all fats and is made up of a
three-carbon chain that connects the fatty acids together. A fatty acid is just a long chain of
carbon atoms connected to each other.
Saturated and Unsaturated
There are two kinds of fats, saturated and unsaturated. Unsaturated fats have at least one
double bond in one of the fatty acids. A double bond happens when four electrons are shared or
exchanged in a bond. They are much stronger than single bonds with only two electrons.
Saturated fats have no double bonds.
Fats have a lot of energy stored up in their molecular bonds. That's why the human body stores
fat as an energy source. When you have extra sugars in your system, your body converts them
into fats. When it needs extra fuel, your body breaks down the fat and uses the energy. Where
one molecule of sugar only gives a small amount of energy, a fat molecule gives off many times
more.
The Nucleic Acids
The nucleic acids are the building blocks of living organisms. You may have heard of DNA
described the same way. Guess what? DNA is just one type of nucleic acid. Some other types
are RNA, mRNA, and tRNA. All of these "NAs" work together to help cells replicate and build
proteins. NA? Hold on. Might that stand for nucleic acid? It might.
While you probably don't have to remember the full words right now, we should tell you that
DNA stands for deoxyribonucleic acid. RNA stands for ribonucleic acid. The mRNA and tRNA
are messenger RNA and transfer RNA, respectively. You may even hear about rRNA which
stands for ribosomal RNA. They are called nucleic acids because scientists first found them in
the nucleus of cells. Now that we have better equipment, nucleic acids have been found in
mitochondria, chloroplasts, and cells that have no nucleus, such as bacteria and viruses.
The Basics
We already told you about the biggie nucleic acids (DNA, mRNA, tRNA). They are actually
made up of chains of base pairs of nucleic acids stretching from as few as three to millions.
When those pairs combine in super long chains (DNA), they make a shape called a double
helix. The double helix shape is like a twisty ladder. The base pairs are the rungs. We're very
close to talking about the biology of cells here. While it doesn't change your knowledge of the
chemistry involved, know that DNA holds your genetic information. Everything you are in
your body is encoded in the DNA found in your cells. Scientists still debate how much of your
personality is even controlled by DNA. Back to the chemistry...
Five Easy Pieces
There are five easy parts of nucleic acids. All nucleic acids are made up of the same building
blocks (monomers). Chemists call the monomers "nucleotides." The five pieces are uracil,
cytosine, thymine, adenine, and guanine. No matter what science class you are in, you will
always hear about ATCG when looking at DNA. Uracil is only found in RNA. Just as there are
twenty (20) amino acids needed by humans to survive, we also require five (5) nucleotides.
These nucleotides are made of three parts:
1. A five-carbon sugar
2. A base that has nitrogen (N) atoms
3. An ion of phosphoric acid known as phosphate (PO43-)
Proteins
We already showed you some information about amino acids. Proteins are made of amino
acids. Even though a protein can be very complex, it is basically a long chain of amino acid
subunits all twisted around like a knot.
Primary Structure
As proteins are being built, they begin as a straight chain of amino acids. This chain structure
is called the primary structure. Sometimes chains can bond to each other with two sulfur (S)
atoms. Those bonds would be called a disulfide bridge.
Secondary Structure
After the primary structure comes the secondary structure. The original chain begins to twist.
It's as if you take a piece of string and twist one end. It slowly begins to curl up. In the amino
acid chain, each of the amino acids interacts with the others and it twists like a corkscrew
(alpha helix) or it takes the shape of a folded sheet (beta sheet). We talked about amino acids
that are hydrophobic and hydrophilic. Those desires to stay away or be close to water (H2O)
play a part in the twisting.
Tertiary Makes Step Three
Let's move on to the tertiary structure of proteins. By now you're probably getting the idea
that proteins do a lot of folding and twisting. The third step in the creation of a protein is the
tertiary structur. The amino acid chains begin to fold even more and bond using more bridges
(the disulfide bridges).
Quaternary Is Fourth and Final
We can finally cover the quaternary structure of proteins. Quaternary means four. This is the
fourth phase in the creation of a protein. In the quaternary structure, several amino acid
chains from the tertiary structures fold together in a blob. You heard us right. "Blob" is the
term we use on this site. They wind, entwined, in and out of each other. Some of the most
famous protein blobs are hemoglobin in human red blood cells and the photosystems in plant
chloroplasts.
Sweet, Sweet Carbs
Carbohydrate is a fancy way of saying "sugar." Scientists came up with the name because the
molecule have many carbon (C) atoms bonded to hydroxide (OH-) groups. Carbohydrates can be
very small or very large molecules, but they are still considered sugars. Plants can create long chains
of these molecules for food storage or structural reasons.
What's It Used For?
A carbohydrate is called an organic compound, because it is made up of a long chain of carbon
atoms. Sugars provide living things with energy and act as substances used for structure. When
sugars are broken down in the mitochondria, they can power cell machinery to create the energy-rich
compound called ATP (adenosine triphosphate). Some examples of structural uses might be the shell
of a crab (chitin) or the stem of a plant (cellulose). We'll talk about them in a little bit.
Saccharides
Scientists also use the word saccharide to describe sugars. If there is only one sugar molecule, it is
called a monosaccharide. If there are two, it is a disaccharide. If there are three, it is a trisaccharide.
You get the idea.
Simple Sugars
What about the simplest of sugars? A sugar called glucose is the most important monosaccharide on
Earth. Glucose (C6H12O6) is created by photosynthesis and used in cellular respiration. When you
think of table sugar, like the kind in candy, it is actually a disaccharide. The sugar on your dinner
table is made of glucose and another monosaccharide called fructose (C6H12O6). These sugars have
the same numbers of atoms, but they are different structures called isomers.
Polysaccharides
When several carbohydrates combine, it is called a polysaccharide ("poly" means many). Hundreds
of sugars can be combined in a branched chain. These chains are also known as starches. You can
find starches in foods such as pasta and potatoes. They are very good sources of energy for your
body.
Sugars for Structure and Support
An important structural polysaccharide is cellulose. Cellulose is found in plants. It is one of those
carbohydrates used to support or protect an organism. Cellulose is in wood and the cell walls of
plants. You know that shirt you're wearing? If it is made of cotton, that's cellulose, too! There can be
thousands of glucose subunits in one large molecule of cellulose. If we were like some herbivores or
insects, such as termites, we could eat cellulose for food. Those animals don't actually digest the
polysaccharides. They have small microorganisms in their bellies that break down the molecules and
release smaller sugars.
Polysaccharides are also used in the shells (chitin) of crustaceans, such as crabs and lobsters. Chitin
is similar in some ways to the structure of cellulose, but has a far different use. The shells are solid,
protective structures that need to be molted (left behind) when the crustacean begins to grow. It is
very inflexible. On the other hand, it is very resistant to damage. While a plant may burn, it takes
very high temperatures to hurt the shell of a crab. If you know the way crabs are cooked, you know
that the crab meat cooks on the inside of the shells when it is boiled. There is no damage to the shells
at the temperature of boiling water (H2O at 100oC).