AP Bio Unit 1 - Barron's 2020

Ionic bonds

transfer of electrons

Covalent bonds

sharing of electrons; molecules

Polar covalent bonds

electrons unequally shared, ex. CO2

Nonpolar covalent bonds

electrons equally shared, ex. Diatomics like H2

What holds H2O molecules together in water?

Hydrogen bonds; weak bonds between H and electronegative atoms (F, N, O)

Water properties

high specific heat (temp regulation); high heat of vaporization (evap of sweat cools); universal solvent (dissolves polar and ionic compounds); strong cohesion tension (attract one another); solid less dense than liquid

Water cohesion effects

transpirational-pull cohesion tension; capillary action; surface tension

Transpirational-pull cohesion tension

when H2O molecule evaporates from tree stomata, another is pulled up by roots

Spring overturn

ice melts on lake which causes water circulation which leads to O2 and nutrient circulation

pH

over 7 is basic (less H+), less than 7 is acidic (more H+); more H+ = lower pH; body wants to stay around 7

Buffer

absorbs or donates H+ to stabilize pH; most common in humans is BICARBONATE ION

Isomers

organic compounds with the same formula but different structures and properties

Structural isomers

different arrangement of atoms

Cis-trans isomers

differ in spacial arrangement around double bonds (aren’t flexible like single bonds)

Enantiomers

mirror images of each other, called L- (left-handed) and D- (right-handed) versions; important for pharma b/c mirror might not have same effect

L-dopa and D-dopa

ENANTIOMERS; L-dopa used to treat Parkinson’s, but D-dopa, its mirror image, useless

All amino acids in cells are

left-handed (L-)

Carbon can form (bonds)

single, double or triple bonds

Shapes of carbon molecules

ring, branch, chain

Carbohydrate composition

CHO

Ration of H to O in all carbohydrates

2H:1O

Empirical formula for all carbohydrates CnH2O

Monosaccharides

C6H12O6; ex. Glucose, galactose, fructose (ISOMERS)

Disaccharides

C12H22O11, 2 monos joined by DEHYDRATION SYNTHESIS/CONDENSATION; ex. Maltose (glucose+glucose), lactose (glucose+galactose)

Dehydration synthesis

aka condensation, creation of polymer by removal of H2O

Hydrolysis

breakdown of compound by adding water, reverse of dehydration synthesis

Polysaccharides

macromolecules; polymers of carbs; ex. Cellulose, starch, chitin, glycogen

Cellulose

plant cell walls; polysaccharides

Starch

plants; 2 forms are amylose and amylopectin; polysaccharide

Chitin

animals; exoskeletons in arthropods and cell walls in mushrooms; polysaccharide

Glycogen

“animal starch”; used for ENERGY and stored in LIVER and skeletal muscle in humans; polysaccharide

Lipids

fats, oils, waxes, steroids; grouped b/c hydrophobic; composed of 1 glycerol and 3 fatty acids

Lipid composition

1 glycerol and 3 fatty acids

Glycerol

alcohol used in lipids

Fatty acid

hydrocarbon chain w/ carboxyl group at end; saturated (straight) or unsaturated (bent)

Saturated fatty acids

solid at room temp; unhealthy; SINGLE BONDS btwn carbon atoms; ex. Butter

Unsaturated fatty acids

liquid at room temp; healthy; AT LEAST ONE DOUBLE BOND formed by removal of H atoms; FEWER H THAN SATURATED

Steroids

lipids w/ 4 fused carbon rings; ex. Cholesterol, testosterone, estradiol

Lipid functions

energy storage, structure (phospholipids, cholesterol=plasma membrane), endocrine (hormones)

Phospholipids

TWO FATTY ACIDS = HYDROPHOBIC TAIL; PHOSPHATE GROUP = HYDROPHILIC HEAD; self-assemble into bilayer in water; basis of ALL plasma membranes

Protein functions

growth and repair, signaling, regulation (insulin hormones), enzyme (catalyze), movement (actin, myosin = muscle contraction)

Actin, myosin

protein fibers responsible for muscle contraction

Protein composition

C, H, O, N, P, S

Protein

polymer/polypeptide of amino acids joined by peptide bonds

Amino acids

composed of carboxyl group, amine group, and variable (R) group (separated by property – hydrophilic, hydrophobic, acidic, basic)

Number of amino acids

20

Dipeptide

2 amino acids connected by peptide bond

Protein conformation

shape that determines function; primary, secondary, tertiary, quaternary

Primary structure

linear sequence of amino acids; one sub can change hemoglobin to sickle cell

Explain the connection between the sequence of the subcomponents of a polymer and its properties

the order of amino acids determines how a protein folds and therefore its function. One substitution can cause major effects – valine -> glutamic acid in hemoglobin causes sickle cell

Secondary structure

results from HYDROGEN BONDING; folds into ALPHA HELIX OR BETA-PLEATED SHEET

Fibrous proteins

proteins with alpha helix or beta-pleated sheet or both; ex. Keratin mostly alpha helixes, silk mostly beta-pleated

Tertiary structure

intricate 3D shape superimposed on secondary structure; determines protein SPECIFICITY; factors are H-bonding between R groups, ionic bonding between R groups, hydrophobic interactions, Van der Waals interactions, disulfide bonds between cysteine amino acids

Factors of tertiary structure

H-bonding between R groups, ionic bonding between R groups, hydrophobic interactions, Van der Waals interactions, disulfide bonds between cysteine amino acids

Quaternary structure

proteins of >1 polypeptide chain; ex. Hemoglobin = 4 heme groups

Chaperone proteins

aka chaperonins; assist in folding other proteins

Misfolded proteins ex

parkinson’s, alzheimer’s, mad cow all from prions (misfolded brain)

X-ray crystallography

used to determine 3d shape/conformation of proteins

Nucleotide composition

phosphate (P), 5 carbon sugar (deoxyribose/ribose), nitrogenous base (ACTGU)

Functional groups

organic molecules most often involved in chem reactions; attached to carbon skeleton; ex. Testosterone vs. estradiol

Functional group examples

amino, carboxyl, hydroxyl, phosphate

Hydrogen

one proton and one electron and NO NEUTRON

Monomers are combined via

dehydration synthesis

Isotopes

same electrons, same protons, different neutrons