Final Exam - Quizzes Flashcards
(15 cards)
G proteins act on
a. tyrosine kinases
b. adenylate cyclase
c. insulin receptors
d. steroid hormones
b. adenylate cyclase
Insulin binds to a receptor that _______.
I. is coupled to a G protein
II. possesses tyrosine kinsase activity
III. possesses serine/threonine phosphatase activity
IV. phosphorylates tyrosine residues of protein targets
a. I only
b. II only
c. I, III
d. II, IV
d. II, IV
the activity of protein kinase A is affected by which of the following?
I. activated adenylate cyclase
II. levels of cAMP
III. phosphodiesterase
a. I only
b. II only
c. III only
d. I and II
e. I, II, and III
e. I, II, and III
Which of the following is TRUE regarding receptor tyrosine kinases?
a. the insulin receptor has two insulin binding sites, one on each subunit
b. ligand binding to the receptor triggers autophosphorylation
c. following ligand binding and dimerization the receptor moves to the nucleus
d. A and B
d. A and B
which of the following would PROLONG a hormone signal mediated via the G protein signal transduction system?
a. addition of a substance that activates protein phosphatases
b. addition of a substance that inhibits phosphodiesterases
c. addition of a substance that inhibits adenylate cyclase
d. B and C
b. addition of a substance that inhibits phosphodiesterases
which are the purine bases?
a. cytosine
b. adenine
c. guanine
d. A and B
e. B and C
e) B and C
which are the pyrimidine bases?
a. cytosine
b. adenine
c. thymine
d. A and C
e. B and C
d. A and C
what is the distinction between a nucleoside and a nucleotide?
a. a nucleoside is present in RNA and a nucleotide is present in DNA
b. a nucleoside has no base attached to the sugar whereas a nucleotide does
c. a nucleoside contains no phosphate groups but a nucleotide does
d. a nucleoside has one phosphate but a nucleotide has three
c. a nucleoside contains no phosphate groups but a nucleotide does
choose the best description of the leading and lagging strands.
a. the leading strand is synthesized continuously and the lagging strand is synthesized discontinuously
b. DNA polymerase synthesizes the leading strand first and then returns to synthesize the lagging strand
c. the leading and lagging strands are both synthesized as Okazaki fragments
d. the lagging strand is attached to the leading strand by the action of single-strand binding protein
a. the leading strand is synthesized continuously and the lagging strand is synthesized discontinuously
helicase is an enzyme that
a. separates the two parental strands
b. promotes hydrogen bonding between complementary bases
c. adds nucleotides to extend a double helix
d. twists two DNA strands into a helix shape
a. separates the two parental strands
a polysome is…
a. a complex consisting of one mRNA to which several ribosomes are attached
b. an aggregate of ribosomal proteins
c. an intermediate stage in the self-assembly of ribosomes
d. a polypeptide chain in the process of being formed
a. a complex consisting of one mRNA to which several ribosomes are attached
a tRNA was determined to have the anticodon sequence of: 3’-GAI-5’ (I represents inosine). Which of the following codons can form base pairs with this anticodon?
a. 5’-CUA-3’
b. 5’-CUC-3’
c. 5’-CUU-3’
d. all of these
d. all of these
aminoacyl-tRNA synthetases are involved in which step of translation?
a. termination
b. elongation
c. initiation
d. activation
d. activation or c. initiation
after peptide bind formation takes place, what step is necessary for continuation of protein synthesis?
a. binding of EF-Tu
b. binding of EF-Ts
c. translocation of the ribosome
d. binding of uncharged tRNA to the ribosome
c. translocation of the ribosome
chain termination occurs, in vivo, when:
a. a hairpin loop forms in the template
b. RNA polymerase gets to the end of DNA
c. none of these
d. either a hairpin loop forms or pho (p) catches up with transcription stalled by a hairpin loop
e. the factor called rho (p) binds to the DNA
d. either a hairpin loop forms or pho (p) catches up with transcription stalled by a hairpin loop
