biologically important molecules

Question 1

Peptide bond formed between the

Answer 1

Carboxyl group of one amino acid and the amino group of another

Question 2

hydrolysis of a protein by another protein is called _____ or ______ ______

Answer 2

proteolysis, proteolytic cleavage

Question 3

the protein that hydrolyzes another protein is called

Answer 3

protease, or proteolytic enzyme

Question 4

disulfide bond

Answer 4

the thiol (SH group) of one cysteine can react with the thiol of another cysteine to form a disulfide bond.

Question 5

disulfide bond plays an important role in stabilizing _____ _____

Answer 5

tertiary protein structure

Question 6

describe secondary structure of a protein

Answer 6

initial folding of polypeptide chain into shapes stabilized by hydrogen bonds between NH and CO groups

Alpha and beta sheets

Question 7

describe tertiary structure of a protein

Answer 7

interactions between AA residues located more distantly from each other on a polypeptide chain (ex: van Der Waals between 2 AAs far apart from one another)

Question 8

quaternary structure of a protein

Answer 8

interactions between polypeptide subunits. forces that stabilize are the same as those that stabilize tertiary structure

Question 9

Carbohydrates can be broken down into ____ by the process ____ which is called burning or combustion

Answer 9

CO2, oxidation

Question 10

the bond between 2 sugars is called

Answer 10

glycosidic linkage

Question 11

glycosidic bonds are what type of bond

Answer 11

covalent

Question 12

glycosidic bonds are formed by a _____ reaction

Answer 12

dehydration

Question 13

starch is the same as glycogen (with exception of minor differences in branching) T to F

Answer 13

true

Question 14

what are the 3 physiological roles of lipids

Answer 14

1) in adipose cells, triacylglyerols store energy
2) in cellular membranes, phospholipids constitute a barrier between intracellular and extracellular environments
3) cholesterol is a special lipid that serves as the building block for the hydrophobic steroid hormones

Question 15

Micelle

Answer 15

a circular formation that lipids form in water. Hydrophobic tails on the inside and hydrophilic heads on the outside

Question 16

fats are more efficient energy storage than carbohydrates

T or F?

Answer 16

true

Question 17

why are fats more efficient energy storage

Answer 17

1) packaging: their hydrophobicity allows for tighter packing than carbs
2) energy content: fat molecules store much more energy than carbs

Question 18

unsaturated fats increase or decrease membrane fluidity

Answer 18

increase, because it disrupts orderly packing of the lipid tails.

Question 19

what are the 3 structural determinants that affect membrane fluidity

Answer 19

degree of saturation, amount of cholesterol, and tail length

Question 20

how does cholesterol affect membrane fluidity

Answer 20

at low temps, cholesterol increases fluidity and at high temps it decreases fluidity

Question 21

steroid hormones are made from _____

Answer 21

cholesterol

Question 22

why is ATP known as a high energy structure at neural pH

Answer 22

it exhibits a large decrease in free energy when it undergoes hydrolytic reactions

Question 23

racemic mixtures are optically ____

Answer 23

inactive because they consist of left and right enantiomers which reflect light in opposite ways from one another to cancel out.

Question 24

which amino acids are basic

Answer 24

histidine, arginine, lysine

Question 25

which amino acids are acidic

Answer 25

glutamate and aspartate