Page 2 AP Biology: 2013 Exam Review
CONCEPT 1 - BIOCHEMISTRY
1. CHNOPS- most common elements in all living matter
2. Bonds- ionic (transfer electrons), covalent (sharing- polar/unequal sharing and non-polar/equal sharing),
hydrogen (weak bonds between hydrogen and negatively charged items), hydrophobic interactions (how
non-polar compounds congregate together- lipids)
3. pH
a. acid-base/ 0-14, # of H ions determines scale; logarithmic- pH 3 = 10
-3
= 1/1000
b. blood- 7.4, stomach- 2, small intestine- 8; enzymes are specific to pH
4. Water properties- polarity, cohesion(attraction to other water molecules), adhesion (attraction to other
charged compounds) low density when frozen, versatile solvent, high heat of fusion/vaporization;
surface tension
5. Organic molecules - monomers are simplest form of all; monomers join together via dehydration synthesis
(loss of water) to make polymers; polymers are broken down via hydrolysis (input of water)
a. Carbohydrates- CHO 1:2:1 ratio, monomer= monosaccharides, 2=disaccharides, 3 or more=
polysaccharides
Used for energy (cell respiration)
Examples
(1) glucose- immediate energy to make ATP
(2) starch- stored energy in plants
(3) glycogen- stored energy in animals (stored in liver)
(4) cellulose- plant cell wall
b. Lipids – C, H, O (not a 1:2:1 ratio) *P only in phospholipids
(1) fats, waxes, oils and sterols
(2) Saturated fats have single bonds between carbons, unsaturated fats have at least one
double bond between carbons (kinky); plants make polyunsaturated; animals make
monounsaturated
(3) Phospholipids make up cell membranes (double layer) and are amphipathic- hydrophilic and
hydrophobic
(4) Uses- in all membranes; stored energy, protection, insulation, myelin sheath of nerves
c. Proteins- C, H, O, N (may have other elements in R group)
(1) Monomer- amino acids (20 total types), 2=dipeptide, 3 or more= polypeptide
(2) Parts of amino acid= carboxyl group (COOH) on one end, amino group on the other end
(NH2), central carbon and variable R group (can be hydrophobic or hydrophilic) which
determines chemical properties.
(3) Protein Folding- shape determines function; primary= a.a. chain; secondary= beta pleated
sheet or alpha helix( hydrogen bonds); tertiary=globular; folds in on itself (disulfide bridges,
hydrogen bonds, hydrophobic interactions; ionic bonding); quartenary= more than one
polypeptide.
(4) Uses- protein carriers in cell membrane, antibodies, hemoglobin, enzymes, most hormones