CSIR NET LIFE SCIENCES - Cytology Questions - Unit 2. Cellular Organization
1. It takes 40 minutes for a typical E. coli cell to completely replicate its chromosome. Simultaneous to the ongoing replication, 20 minutes of a fresh round of replication is completed before the cell divides. What would be the generation time of E. coli growing at in complex medium? (Dec 2015)
a. 20 minutes
b. 40 minutes
c. 60 minutes
d. 30 minutes
Ans: a. 20 minutes
2. Glycophorin having one highly hydrophobic domain is able to span a phospholipid bilayer membrane only
d. four times
Ans: 1. once
3. Given below are events in the cell cycle.
(a) Phosphorylation of lamin A, B, C
(b) Phosphorylation of Rb (Retinoblastoma protein)
(c) Polyubiquitination of securin
(d) Association of inner nuclear membrane proteins and nuclear pore complex
proteins with chromosomes.
Which one of the following reflects the correct sequence of events in the mammalian cell cycle?
Ans: 4. b->a->c->d
4. Predominant interactions between phospholipids that stabilize a biological membrane include (June 2016)
a. hydrogen bonds and covalent interactions.
b. van der Waal and ionic interactions.
c. hydrophobic interactions and hydrogen bonding.
d. covalent and hydrophobic interactions.
Ans: c. hydrophobic interactions and hydrogen bonding.
5 . Entry of enveloped viruses into its host cells is mediated by: (June 2016)
a. Only endocytosis
b. Both endocytosis and phagocytosis
c. Both endocytosis and membrane fusion
d. Only pinocytosis
Ans: c. Both endocytosis and membrane fusion
6 . Lateral diffusion of proteins in membrane can be followed and diffusion rate calculated by (June 2016)
a. Atomic force microscopy
b. Scanning electron microscopy
c. Transmission electron microscopy
d. FRAP (Fluorescence recovery after photobleaching)
Ans: d. FRAP (Fluorescence Recovery After Photobleaching)
7. Labelling of membrane spanning domain of any integral membrane protein in a given plasma membrane vesicle (without disrupting its structure) is successfully carried out by (June, 2016)
a. immunochemical methods.
b. metabolic labelling with radioisotopes.
c. hydrophobic photoaffinity labelling.
d. limited proteolysis followed by metabolic labelling.
Ans: c. hydrophobic photoaffinity labelling.
8. Which one of the following describes the primary function of flippases? (dec, 2016)
a. Help in increasing lipid-protein interaction in the outer leaflet of the bilayer
b. Move certain phospholipids from one leaflet of the membrane to another
c. Localize more negatively charged membrane proteins in the lipid bilayer
d. Cause uncoupling of v-SNARES and t-SNARES after fusion of incoming vesicle
with target membrane
Ans:b. Move certain phospholipids from one leaflet of the membrane to another
9. Mitotic cyclin-CDK activity peaks in M phase. This is because
a. Mitotic cyclin is synthesised only in M phase.
b. Threshold level of mitotic cyclin accumulates only in late G2.
c. Cyclin subunit is activated by phosphorylation only in M phase.
d. The kinase subunit is activated by dephosphorylation only in M phase.
Ans: d. The kinase subunit is activated by dephosphorylation only in M phase.