AP Biology Unit 1

Chapters 2 and 3 in the textbook

Standard Error of the Mean

How well a sample represents the mean of the population

Covalent Bonds

Bonds where atoms share electrons

HONC Valence

1, 2, 3, 4

Van Der Walls Interactions (London Disperson Forces)

Attractive forces that exist between all molecules. They are weak individually, but can be strong together

Hydrogen Bonds

Weak bonds between polar hydrogen and Nitrogen, Oxygen, or Flourine (less common) on another polar molecule

Hydroxyl Group

(—OH), in Carbohydrates

Carbonyl Group

(—CO), in lipids and carbohydrates, is polar

Carboxyl Group

(—COOH), in proteins, acidic

Amino Group

(—NH₂), in proteins, basic

Sulfhydryl Group

(—SH), in proteins, can cross-link to form disulfide bonds

Phosphate Group

(—PO₄), important in DNA and ATP, in Phospholipids, helps energy transfer

Hydrolysis

Water “attacks” the covalent bond between monomers, leaving one monomer with a hydroxyl and the other with a hydrogen.

Dehydration Synthesis

(—OH) on one monomer joins —H on another monomer. H₂O is made and leaves the molecule, and the two monomers bond.

Carbohydrate General Formula

C_nH_2nO_n

Function Groups in Carbohydrates

Hydroxyl and Carbonyl groups

Carbohydrate Functions

Structure or fuel

Monosaccharides

Simple sugars, one ring. Ex: Glucose

Disaccharides

Two rings. Ex: Lactose and sucrose

Polysaccharides

Complex carbohydrates, long chain of monosaccharides (linear or branched)

Carbohydrate Examples

Cellulose (plant cell wall, fiber source in diet), starch (energy storage in plants - dietary glucose), Glycogen (energy storage for animals - stored in liver and muscle)

Lipids Functions

Energy storage and structure

Saturated Fats

Only single bonds in the carbon chain (straight), solid at room temperature, forms plaques in blood vessels. Ex: Steak fat, bacon fat, butter

Unsaturated Fats

At least one double bond in the carbon chain (bends), liquid at room temperature, better for health. Ex: Vegetable oil, olive oil

Trans Fats

Unsaturated fats synthetically solidified by adding hydrogen, contribute to heart disease.

Fats

Lipid: energy storage (most energy dense macromolecule), insulation, made of Glycerol + up to 3 fatty acid tails

Steroids

Lipid: Hormones (cell communication, growth, development, physiology, homeostasis), made for 4 rings. Ex: Cholesterol

Phospholipid

Form the lipid bilayer of the cell membrane, have a hydrophilic “head” with hydrophobic “tails”

Nucleic Acids Function

Contain genetic information

Nucleic Acids Structure

Phosphate, 5C sugar (ribose or deoxyribose), Nitrogenous base (A, T - DNA only, C, G, U - RNA only), Purines (2 ring) include A and G, Pyrimidines (1 ring) include T, U, and C

DNA

Two strands held by hydrogen bonds between base pairs, double helix with antiparallel strands, pairs A to T and C to G

RNA vs. DNA

RNA is single stranded, contains Uracil instead of Thymine, and has Ribose instead of Deoxyribose (which is in DNA)

Proteins

Do almost everything for the cell, monomer is Amino Acids, Polymer is Polypeptide

Amino Acid Structure

Central carbon is bonded to hydrogen, amino group, carboxyl group, and an R group (1 of 20 structures), dehydration synthesis forms peptibe bonds between them

Protein Primary Structure

Chain of amino acids

Protein Secondary Structure

Caused by hydrogen bonding of the backbone, can be alpha helix coil or beta pleated sheet (folded back and forth in parallel segments)

Protein Tertiary Structure

Creates 3D shape, caused by interactions between R-groups. Interactions: Hydrogen bonds, hydrophobic interactions, ionic interactions, and disulfide bridges

Protein Quaternary Structure

Combination of 2 or more polypeptides, not present in all proteins

Denature

Interactions in a protein are destroyed, causing it to unravel and lose shape.