Macromolecules Notes: Ch. 3

KEY WORDS/
QUESTIONS / NOTES
General Vocabulary: / Monomers: subunits that make up larger molecules. “Parts that make up the whole.”
Polymers: a bunch of monomers all hooked together. The whole thing!
Examples:
1. Legos vs. Legoland
2. Bono vs. U2
3. A cinderblock vs. HamiltonHigh School
Dehydration Synthesis:

AKA. Condensation reaction

  • Process used to create polymers from the monomers.
  • Used in anabolic reactions in the body (Reactions that BUILD molecules.)
  • Water is formed during the process. Why? b/c in order to hook subunits together, they need to be able to share electrons. If there are no electrons to be shared, they won’t/don’t need to form a bond. So...
  • ...by removing an -H from one subunit and an –OH from the other subunit, you have freed up electrons that will now bond together to form the covalent links that connect the monomers. The H and OH form water.
  • In the body these reactions are carried out by enzymes known generally as POLYMERASES.
Hydrolysis:
  • Process used to release monomers from the larger polymer.
  • Used in catabolic reactions in the body (Reactions that BREAK DOWN molecules.)
  • Water is used during the process. Why? b/c now you have to break up one or more of the covalent links. This leaves unhappy atoms with electrons that need to be shared. So...
  • ...water breaks up into –H and –OH and attaches to make each side happy.
  • In the body these reactions are carried out by enzymes known generally as HYDROLASES.
Polymerization: process that creates polymers from monomer subunits.
Macromolecules: organic molecules found in the body can be classified as one of four things: proteins, nucleic acids, carbohydrates and lipids. These are known as macromolecules because they can be very large. These are the “bricks and mortar” of our bodies...they make up the cells and everything in them.

CARBOHYDRATES

Structure: / How can you tell carbohydrates apart from other molecules?
  • Only made of carbon, hydrogen and oxygen
  • If given the formula: characteristic 1:2:1 ratio
  • If given the name: most end with “-ose”
  • If given the structure: look for the hexagon shape...but then double check by looking for the ratios. If not listed, each corner of the hexagon is a carbon. Sometimes they aren’t always shown.
Monomer: simple sugar/monosaccharide
Polymer: polysaccharide
Types: / A. Monosaccharide: aka simple carbohydrate
Ex. Glucose, fructose, galactose
Interesting notes:
  • All the examples listed above have the same molecular formula. So how are they different? The atoms are hooked together differently. These are known as ISOMERS.
B. Disaccharides: aka simple carbohydrate
Ex. Sucrose, maltose, lactose
C. Polysaccharides: aka complex carbohydrate
Ex. Cellulose, glycogen, chitin, starch
Interesting:
  • All of the examples listed above are polymers of glucose! So if they are all made of only glucose how are they different?
  • They differ in the way the glucose molecules are attached. Cellulose and chitin are STRUCTURAL polymers made with one type of glucose. Glycogen and starch are ENERGY polymers made with the other form of starch.
  • Who cares? Cellulose and chitin are used in plants and animals respectively for constructing cell walls and exoskeletons. We (plants and animals) don’t have the enzymes that recognize how the glucose molecules are hooked together in this form...so we don’t digest these forms! Good thing...if plants had the enzyme they would have to find something else to build their cell walls out of.

Testing for Carbs /
  1. Iodine Test: Indicates the presence of starch.
  2. A positive test turns purple.
  1. Benedicts Test: Indicates the presence of monosaccharides.
  2. A positive test turns orangy.

LIPIDS

Structure: / How can you tell Lipids apart from other molecules?
  • Made of carbon, hydrogen, oxygen and other elements...typically phosphorous and nitrogen
  • If given the formula: no characteristic ratio
  • If given the name: no fancy way to tell. Sorry!
  • If given the structure: since there are three classes of lipids, they each have a recognizable shape: (See under “types” below)
Monomer: Fatty Acids
Polymer: Three exist: a. Triglyceride
  1. Phospholipids
  2. Steroids (Cholesterol)

Types: / A. Triglycerides:
  • Made by attaching the glycerol head to the three fatty acid tails. (Known as triglycerides)
  • The fatty acid tails can be saturated or unsaturated depending on the presence or absence of double bonds.
  • This molecule is entirely hydrophobic!
  • Who cares? Unsaturated fats are liquid at room temperature since they can’t pack tightly. Hence, easier for the body to digest and don’t build up in the blood stream. Saturated fats are solid at room temp, can pack tightly together, so makes it harder for the body to digest.
  • Typical Structure:
  • Tails can be all saturated, all unsaturated or a combination.
B. Phospholipids:
  • Made by taking off one of the fatty acid tails and replacing it with a molecule known as a “phosphate group”
  • By adding this group, you have now made a portion of the molecule hydrophobic (the tails) and a portion is now hydrophilic (the head)
  • So what? You can now use this molecule as a type of sack! When dropped into water, they form spheres with the heads facing the water and the tails in the middle. You can put stuff inside them!
  • Typical Structure:
C. Steroids:
  • Made by combining tons of fatty acids into rings.
  • Characterized by looking for the fused rings: (Don’t worry about the numbers!)

Testing for Lipids: /
  1. Emulsification Test: forms two layers when heated in water and subsequently having ethanol poured in
  2. Brown Paper Bag Test
  3. Sudan IV Test: Turns red in the presence of a fat

Proteins

Structure: / How can you tell proteins apart from other molecules?
  • Made of carbon, hydrogen, oxygen, sulfur, etc.
  • If given the formula: no characteristic ratio
  • If given the name: most end with “-in”
  • If given the structure: look for the N – C – C (See below)
Monomer: amino acid
Key parts to the amino acid:
Polymer: protein or polypeptide (named because the covalent bond that links the monomers is known as a peptide bond.) Show how they bond together and you can tell how many AA you have by looking at the # of NCC-s in a chain.
Levels of Organization: / When proteins are made in living organisms they are QUITE LARGE! A typical protein has about 50, 000 amino acids. So they conserve space within the cell, they are packed tightly. We will talk about how this happens later, but for now, these are the levels of protein packaging:
1. Primary Structure: a simple chain of monomers. The order the amino acids line up is dictated by the DNA code.
2. Secondary Structure: the chain starts to coil (AKA alpha helices) (like a telephone cord) and other parts of the chain will accordion fold (AKA beta-pleated sheets)
KEY: They maintain their shape because parts of the backbone forms hydrogen bonds (N from one amino group on one amino acid bond to the O in the carboxyl group of another aa)
3. Tertiary Structure: the coils and pleats now start folding in on each other! KEY: The shape is maintained by bonding at the R group level! Important here is to know whether the amino acids are hydrophobic or hydrophilic...the hydrophobic ones will cause the protein to bend (during folding) away from water. The hydrophilic won’t be bothered in the presence of water.
  • All proteins are at least at this stage.
  • Examples: keratin, antibodies, collagen
  • All enzymes are at this stage. (Few exceptions)
4. Quaternary Structure: two proteins at the tertiary stage have combined.
  • Example: hemoglobin

Testing for Proteins: / 1. Buiret’s Test: turns a pretty purple if proteins are there!

Nucleic Acids

Structure: / Monomer: nucleotides
Cool song: (Sung to Row, Row, Row Your Boat)
“We love DNA, made of nucleotides
Sugar, phosphate and a base bonded down one side.
Adenine and thymine make a lovely pair.
Cytosine without guanine would be oh so bare...OH”

Polymer: DNA or RNA
Testing for Nucleic Acids: / Don’t worry about!