ACS STUDY

  1. which enzyme is responsible for prepping glucose inside the cell?

a. glucose-6-phosphatase

b. phosphohexose isomerase

c. glycogen synthase → links glucose together

d. hexokinase → first step to phosphorylate

  1. what is the next ATP output for two molecules of glucose during glycolysis?

a. 2

b. 4 → from two molecules of glucose after glycolysis

c. 6

d. 8

  1. all of these enzymes involve the transfer of a phosphoryl group. Which catalyzes a reaction that produces ATP?

a. glycogen phosphorylase

b. glyceraldehyde-3-phosphate dehydrogenase

c. pyruvate kinase → last step

d. hexokinase

  1. how does the allosteric modulator, fructose-2-,6-bisphosphate, directly regulate gluconeogenesis?

a. activation of phosphofructokinase-1

b. activation of fructose-1,6-bisphosphatase

c. inhibition of phosphofructokinase-1

d. inhibition of fructose-1,6-bisphosphatase

  1. in a protein, which amino acid has the least flexibility in its conformation, and which has the most flexibility?

a. pro, gly → gly has 2 H = more flexibility

b. met, cys

c. trp, gly

d. Ile, ala

  1. which amino acid is most likely to disrupt an alpha helix when located in the middle of the helical segment?

a. glycine → one of the helix breakers with a small side chain = causes improper angles

b. leucine

c. glutamic acid

d. isoleucine

  1. Given that leucine has pk1 = 2.33 and pk2 = 9.74, which form will leucine predominantly exist in at a pH of 11.0? [this is really basic = removed protons]

a. NH3+-CH(CH2CH(CH3)2)-COOH → below pKA

b. NH3+-CH(CH2CH(CH3)2)-COO- → occurs between two of the pKas

c. NH2-CH(CH2CH(CH3)2)-COO-

d. none of the above

  1. At which pH value will arginine be in its zwitterionic form?

→ arginine: pK1 (carboxyl) = 1.82, pK2 (amino) = 8.99, and pKr (side chain, guanidino) = 12.48.

a. 6.20

b. 10.74

c. 7.61

d. 12.51

→ basic = side chain and amine

  1. Which pH represents the isoelectric point (pI) of glutamic acid?

→ glutamic acid: pK1 (carboxyl) = 2.10, pK2 (amino) = 9.47, and pKR (side chain, y-COOH) = 4.07.

a. 3.09

b. 5.96

c. 6.72

d. 7.12

→ acidic = side chain and carboxyl

  1. which amino acid would most likely be found on the surface of a soluble protein?

a. phe

b. met

c. glu

d. val

  1. which pair of amino acids is most likely to form a disulfide bond, thereby contributing to the stabilization of a protein’s tertiary structure?

a. serine and threonine

b. cysteine and cysteine → only only capable of making a disulfide bond

c. tyrosine and tryptophan

d. glutamate and lysine

  1. which event is the initial step in the folding process of an unfolded polypeptide chain into its functional protein structure in a hydrophilic environment?

a. fine-tuning of the tertiary structure

b. clustering of hydrophobic regions within the protein

c. assembly of organized subunits

d. reaching a low energy state

  1. the impact of an enzyme on a biochemical reaction is to

a. alter the equilibrium constant for the reaction and allow it to occur more readily

b. increase the reactivity of functional groups making reactions more likely to occur

c. provide an alternative, lower energy pathway for the reaction by decreasing the activation energy

d. store energy that can later be retrieved

  1. enzymes are typically

a. proteins

b. sugars

c. fats

d. nucleic acids

  1. enzymes ___ rates of reaction by ___ the activation energy.

a. slow down, lowering

b. speed up, lowering

c. slow down, raising

d. speed up, raising