In cell cycle: a. M phase is both the most complex and the longest phase b. ther
ID: 1064655 • Letter: I
Question
In cell cycle:
a. M phase is both the most complex and the longest phase
b. there is a G0 phase in equilibrium with the G1 phase
c. quiescent cells cannot be induced to reenter the cell cycle
d. microtubule spindles form during the S phase
e. the order of phases is G1, G2, S, and M
2. cyclin-dependent kinase (Cdks):
a. occur onlu int he M phase
b. are always inactivated by phosphorylation
c. typically phosphorylate proteins on tyrosine residues
d. in addition to binding cyclin, require other modifications for activity
e. that phosphorylate Rb (retinoblastoma sensitivity) protein inhibit the synthesis of S-phase proteins
3. elements of growth factor pathway regulation of the cell cycle include all of the following except:
a. dimerization or polymerization of receptor proteins in the plasma membrane
b. binding of ATP to a tyrosine kinase domain of growth factor receptor proteins
c. nonspecific bidning of SH2 or SH3 domains to any phosphorylated tyrosine
d. conformational changes of proteins as part of signal transmission
e. location of the growth factor receptor protins in the plasma membrane
4. one inducer of apoptosis is DNA damage acting via p53, a transcription factor, p53:
a. is activated by kinases located in chromatin
b. increases the transcription of several pro-apoptotic genes for Bcl-2proteins
c. concentration is normally because it is subject to ubiquitination
d. concentration may be increase by acetylation
e. all of the above are correct
5. protoocogenes:
a. produce protein products that promote cell division
b. produce protein products that promote apoptosis
c. are converted to oncogenes by a mutatino that inhibits their expression
d. require both alleles to be mutated to show a pro-proliferative effect
e. are constituitvely activated
6. tumor suppressor genes
a. have the same effect as protooncogenes
b. contribute to cancer if only one allele is inactivated by mutation
c. produce protein products that promote apoptosis
d. produce products that promote cancer
e. all of the above are correct
7. the gene for which of the following would be considered a protooncogene?
a. p53
b. Rb protein
c. p21 (a Cdk inhibitor protein)
d. genes for Bcl-2-like proteins
e. Ras
8. Ras proteins of the signal pathway
a. is inactive in the GDP-Ras conformation
b. transmits a signal by initiating a kinase cascade
c. from a mutated gene in many cancers has inactiavted GTPase activity so inhibits the downstream signal to divide
d. is formed from an oncogene
e. becomes inactive as a signaling prtein by phosphorylation transcription factors.
9. apoptotic death of a cell may include all the follpwing except:
a. lysis of the cell membrane with inflammatino
b. activation of enzymes called caspases
c. phagocytosis
d. bidning of a ligand in the extracellular environment to a plas membrane receptor
10. Malignant cancer cells have all the following properties except"
a. unregulated cell division
b. inhibition of angiogenesis
c. resistance to apoptosis
d. cellular immortality
e. abilut to metastasize
11. the property of cellular immortablity refers to a cell's ability to:
a. grow new blood vessels
b. invade through the basement membrane of its tissue
c. resist apoptosis
d. continue to divide indefinitely without limit to the number of generations
e. grow tumors at a multiple sites
12. telomerase:
a. activity generally increase as an individual ages
b. catalyzes the resynthesis of telomer regions
c. activity is high during all stages of the carcinogensis process
d. plays a role in apoptosis but not immortality
e. when present at a hih level, leads to cell senescence
Explanation / Answer
5. produce protein products that promote cell division
6 produce protein products that promote apoptosis
7 Ras
10. inhibition of angiogenesis
11 resist apoptosis
12 catalyzes the resynthesis of telomer regions
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