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Cell biology multiple choice questions

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1. Calmodulin
a. is an ubiquitous protein in eukaryotic cells
b. binds Ca2+
c. is a membrane bound protein
d. a and b

2. All of the following properties about nitric oxide are true EXCEPT:
a. is a gas
b. is synthesized from O2 and arginine
c. has a half-life of 2-3 minutes
d. activates guanylyl cyclase

3. A gain-of-function in which of the following would promote malignancy in cells whose proliferation is inhibited by TGF?
a. co-Smad
b. I-Smad
c. R-Smad
d. all of the above

4. Which of the following receptors binds TGF?
a. type I
b. type II
c. type III
d. types I and II
e. types II and III

5. Which of the following events occurs during the epinephrine-stimulated conversion of glycogen to glucose-1-phosphate?
a. inhibition of PKA by cAMP
b. inhibition of glycogen synthase
c. inhibition of glycogen phosphorylase
d. activation of glycogen synthase

6. cGMP phosphodiesterase catalyzes the conversion of
a. cAMP to cGMP
b. cGMP to 5'-GMP
c. GTP to cGMP
d. cGMP to GDP

7. Binding of hormone to a receptor tyrosine kinase causes all of the following EXCEPT:
a. dimerization of the receptor
b. autophosphorylation of the receptor
c. activation of Ras through an interaction with GRB2 and Sos
d. hydrolysis of GTP bound to Ras

8. In the MAP kinase pathway .p90RSK phosphorlates
a. MEK
b. MAP kinase
c. serum response factor
d. RAF

9. In the MAP kinase pathway . p90RSK is phosphorylated by:
a. MEK
b. MAP kinase
c. serum response factor
d. RAF

10. The discovery of green fluorescent protein (GFP) has greatly facilitated living cell experiments because
a. GRP is green
b. GFP requires a jellyfish-specific cofactor
c. GFP sequences may be readily fused to those of other proteins
d. wild-type GFP folding is adapted to normal sea water temperatures, 15-25◦C

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Solution Preview

1. Calmodulin
a. is an ubiquitous protein in eukaryotic cells
b. binds Ca2+
c. is a membrane bound protein
d. a and b

Ans. d

Calmodulin (CaM) is a ubiquitous, calcium-binding protein that can bind to and regulate a multitude of different protein targets, thereby affecting many different cellular functions. CaM is expressed in many cell types and can have different subcellular locations, including the cytoplasm, within organelles, or associated with the plasma or organelle membranes.

2. All of the following properties about nitric oxide are true EXCEPT:
a. is a gas
b. is synthesized from O2 and arginine
c. has a half-life of 2-3 minutes
d. activates guanylyl cyclase

Ans. c

Nitric oxide is a gas, NOis synthesized from arginine with the aid of molecular oxygen and NADPH in presence of NO synthase.The most common protein target for NO seems to be guanylyl cyclase, the enzyme that generates the second messenger cyclic GMP (cGMP). NO has a half-life of only a few seconds in vivo.

3. A gain-of-function in which of the following ...

Solution Summary

This solution provides answers to multiple choice questions from cell biology. It also provides explanation to the answers.

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Cell Biology Multiple Choice questions

1. Protein insertion into the mammalian ER membrane is typically
a. cotranslational c. pretranslational
b. post-translational d. quasitranslational

2. In N-glycosylation of proteins in the ER lumen, sugar(s) are added to the nascent chain at once.
a. 1 c. 7
b. 3 d. 14

3. All of the following proteins interact with exposed amino acids during protein folding in the ER except:
a. BiP c. PDI (protein disulfide isomerase)
b. calnexin and calreticulin d. prolylisomerase

4. Type I membrane proteins have all of the following properties except:
a. cleavable signal sequence c. internal stop-transfer sequence
b. internal signal-anchor sequence d. N-out, C-in topology

5. Proteins that do not fold properly in the ER lumen are degraded in the cytosol by
a. the etiosome c. the proteasome
b. the microsome d. the ribosome

6. Sorting of protein to mitochondrian and chloroplasts is
a. cotranslational c. pretranslational
b. post-translational d. quasitranslational

7. Tom/Tim and Toc/Tic protein complexes are involved in
a. post-receptor recognition events in the cytosolic folding of proteins prior to import into mitochondria or chloroplasts
b. pre-proteasomal steps in tagging aged proteins for degradation
c. protein translocation into mitochondria and chloroplasts, respectively
d. resetting biological clocks following rounds of intense protein synthesis

8. Protein sequences for targeting to mitochondria or chloroplasts are located at
a. the C-terminus of the precursor protein
b. amino acid position 173 in most mitochondrial and chloroplast proteins
c. the N-terminus of the precursor protein
d. At neither terminus.

9. Many peroxisomal matrix proteins are imported as
a. folded proteins
b. nascent chains in the process of completing their elongation
c. protein fragments that are spliced together within the peroxisome
d. unfolded proteins

10. Tom is an abbreviation for _____________________________________________________.

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