RAT #13 - Regulating Protein Function

Question 1

Feedback inibition is a type of “allosteric regulation” in which a molecule binds to _________ and inhibits its _________?

a. the catalytic site on an enzyme; activity
b. a site on an enzyme distinct from the catalytic site; activity

c. the mRNA for an enzyme; synthesis
d. the gene for an enzyme; synthesis

Answer 1

b. a site on an enzyme distinct from the catalytic site; activity

Question 2

{True / False}

Allosteric regulation is mediated through the covalent association of a small molecule to a protein.

Answer 2

FALSE

Question 3

A hydrogen bond is?

a. weak to moderate interaction between hydrogen of one molecule and an oxygen or nitrogen of a second eletronegative molecule
b. a bond formed by equal sharing of electrons between two atoms
c. the linear sequence of the amino acid constituents of a protein
d. nonspecific interactions between molecules caused by transient dipoles (random flucuations in the districution of electrons)
e. attractions between oppositely charged ions

Answer 3

a. weak to moderate interaction between hydrogen of one molecule and an oxygen or nitrogen of a second eletronegative molecule

Question 4

{True / False}

Phosphorylation of proteins is permanent.

Answer 4

FALSE

Question 5

Which of the following Amino Acids is NOT Phosphorylated to REGULATE Protein Activity?

a. tryptophan

b. serine
c. tyrosine

d. threonine

Answer 5

a. tryptophan

Question 6

Proteins are often Regulated by Phosphorylation, which is MEDIATED by Enzymes called?

a. Protein Phosphatases
b. Protein Kinase
c. Protein Phosphorylases
d. phosphoproteases

Answer 6

b. Protein Kinase

Question 7

The Amount of Protein in a Cell is REGULATED by the Rate of ?

a. transcription of its gene

b. translation of its mRNA
c. degradation of the protein

d. all of the above

Answer 7

a. transcription of its gene

b. translation of its mRNA
c. degradation of the protein

d. all of the above

Question 8

Secondary structure is?

a. Regular arrangement of amino acids within localized regions of the polypeptide
b. a bond formed by the equal sharing of electrons between two atoms

c. attractions between opposite charged ions
d. the linear sequence of the amino acid constituents of a protein

e. the overall folding of the polypetide chain as a result of interactions between the side chains of amino acids that lie in different regions of the primary sequence

Answer 8

a. Regular arrangement of amino acids within localized regions of the polypeptide

Question 9

Monomeric G proteins like Ras and several translation elongation factors are usually in the active state when a molecule of which of the following binds to them?

a. ATP
b. ADP
c. GDP
d. GTP

Answer 9

d. GTP

Question 10

Which of the following is NOT a Mechanism for Regulating Protein Function?

a. Regulation by Protein Phosphorylation
b. Regulation by Protein-Protein Interactions

c. Regulation by Small Molecules
d. Regulation by MicroRNAs
e. Regulation by Protein Degradation

Answer 10

d. Regulation by microRNAs