Question

1.)Most transduction systems for hormones and sensory stimuli thatinvolve trimeric G proteins have in common all of the followingexcept:
A) cyclic nucleotides.
B) nuclear receptors.
C) receptors that interact with a G protein.
D) receptors with multiple transmembrane segments.
E) self-inactivation.

2.)The G-protein involved in visual signal transduction is:
A) a leukotriene.
B) transducin.
C) arrestin.
D) rhodopsin.
E) a GTP receptor.

3.) Which of the following statements concerning cyclin-dependentprotein kinases is not correct?
A) Each type of cell contains one specific form (isozyme).
B) Their activity fluctuates during the cell cycle.
C) Their activity is regulated by changes in gene expression,protein phosphorylation, and proteolysis.
D) Their activity is regulated by cyclins.
E) They can alter the activity of proteins involved in theprogression of cells through the cell cycle.

4.) Which of the following statements concerning cyclins is notcorrect?
A) They are activated and degraded during the cell cycle.
B) They are regulatory subunits for enzymes that catalyze thephosphorylation of proteins.
C) They can become linked to ubiquitin.
D) They catalyze the phosphorylation of proteins.
E) They contain specific amino acid sequences that target them forproteolysis.

5.) Proto-oncogenes can be transformed to oncogenes by all of thefollowing mechanisms except:
A) chemically induced mutagenesis.
B) chromosomal rearrangements.
C) during a viral infection cycle.
D) elimination of their start signals for translation.
E) radiation-induced mutation.