BIO CHP 2 - Biological Molecules

II. Biological Molecules

A. Introduction [ugh... intros...]
-- The study of biochemistry - explores structure and function of molecules in living organisms
-- Organic molecules - molecules with the Carbon atom in it. [The only exception is carbon dioxide, CO2... go SAT II Bio book!]
-- Macromolecules - relatively large molecules [organic larger than inorganic... usually] and are usually polymers - molecules formed by adding smaller subunits - monomers. [so many definitions... except you should know all this already.]

B. Carbohydrates [yay carbs... I learned how to spell monosaccharides, disaccharides, and polysaccharides from this outline :)]
-- Carbohydrates - named carbohydrates because it's mainly composed of Carbon and Water, usually in the formula of: [C(H2O)]n [<-- that bracket is not my comment but this is.]
- 1. Monosaccharides - simplest carbohydrate subunits found in nature. They're usually suit and known as "sugars" or "simple carbohydrates". Monosacharides are usually 6-Carbon compounds.
--- glucose - C6H12O6
--- fructose - C6H12O6
--- galactose - C6H12O6
[The general formulas are the same, but the bonds are different]
--- Important 5-Carbon sugars: ribose/deoxyribose [this should sound familiar, if not, you fail at bio :)] - C5H10O5/C5H10O4 [yes that's why it's deoxy-ribose]
- 2. Disacharides - Compose of two monosaccharides [di!] joined by a glycosidic bond. These are also fairly simple sugars.
--- sucrose - table sugar = fructose + glucoses
--- lactose - "milk sugar" = glucose + galactose
--- maltose - "malt sugar" = glucose + glucose
[must be broken down into monosaccharides before bonding]
3. Polysaccharides - composed of many, often hundreds, or monosaccharide units.
-- in nature, all the important polysaccharides are flucose polymers [yay go glucose], differing in their physical arrangement
--- Starch - energy storage in plants and one of the most consumed polysaccharides
--- Cellulose - makes up the cell wall of plants
--- Glycogen - "animal starch" - how animals store excess glucose in their livers and muscles as an energy reserve.

C. Lipids - macromolecules grouped together; lipids do not dissolve in water. They contain nonpolar covalent bonds, largely composed of hydrocarbon chains/rings
- 1. Triglycerides - composed of one molecule of trialcohol glycerol covalently attached to 3 fatty acids.
-- Chains containing double bonds are called unsaturated, the more unsaturated a fatty acid chain is, the more liquidy the triglyceride is. Oils are usually known as polyunsaturated triglycerides.


- 2. Phospholipids - They resemble triglycerides, but a hydrophilic molecule containing a phospate group is in place of one of the fatty acids, giving the molecule a hydrophobic tail and a hydrophilic head [aka amphipathic molecule - one philic, one phobic]. Phospholipids form structures of plasma membranes and can also act as emulsifying agents - agents that allow other lipids to dissolve more easily in the body.

- 3. Steroids - lipids that don't resemble triglycerides but are composed of a series of nonpolar rings. Cholestrol is the most wellknown and prevalent steroid compound in the body. Other important ones include sex hormones and vitamin D.


D. Proteins - polymeric macromolecules made up of subunits called animo acids, which differ by an "R" group.

FOUR LEVELS OF PROTEIN STRUCTURE:
- 1. Primary Structure: linear order of amino acids
- 2. Secondary Structure: hydrogen bonds between atoms of adjacent amino and acid groups. Common secondary structures: alpha-helix and beta-pleated sheets.
- 3. Tertiary Structure: ultimate 3D shape. It folds due to long range interactions between R-groups of amino acids: hydrogen bonding, electrostatic interactions, and hydrophobic interactions. Tertiary structure is responsible for the protein's function.
- 4. Quaternary Structure - not all proteins have a quaternary structure, only those that ave multiple polypeptide chains. Its folding refers to the interactions between multiple chains of amino acids to make a protein that can only function in this state.
-- Proteins also function as enzymes, antibodies, structural components, hormones... etc
-- Hemoglobin: help carries oxygen in blood
-- Collagen and Keratin - major components of hair, skin, and connective tissues
-- Insulin - hormone that regulates blood glucose levels [yay hormones! my fav subject]
-- Pepsin - enzyme that digests other proteins in the stomach, functions best in acidic places with pH between 1.5 - 2 [aka your stomache is acidic... in case you did not know that]

E. Nucleic Acids - macromolecular polymers made up of nucleotide subunits.
-- a nucleotide contains a 5-carbon sugar [yes this is when ribose and deoxyribose comes in handy :)], a nitrogenous base, and a phosphate group.
-- Adenine [purine] - Thymine [pyrimidine]-->(Uracil [pyrimidine] in RNA}
-- Guanine [purine] - Cytosine [pyrimidine]
-- Nucleotides are joined to one another by phosphodiester bonds [a group of strong covalent bonds between the phosphorus atom in a phosphate group and two other molecules over two ester bonds --> go wikipedia].