131.

Fluorescence recovery after photobleaching (FRAP) is a method to estimate the diffusion of molecules in a membrane. Fluorescently labeled molecules such as-

i. a receptor tagged with green fluorescent protein(GFP)

ii. a receptor labeled with GFP which interacts with cytoskeleton.

iii. a labeled lipid.

iv. a labeled protein that binds to the membrane surface

are photobleached and the recovery profiles (a-d) were obtained to estimate their diffusion coefficients.

The following data were obtained:

Which one of the combinations is correct?

• a - i; b - ii

• b - iii; a - iv

• c - iii; d - iv

• d - ii; b - i

Rotenone is an inhibitor of the electron transport chain. The addition of rotenone to cells results in which of the following?

• Generation of mitochondrial reactive oxygen species and block in ATP generation.

• Block in ATP generation but no generation of reactive oxygen species.

• Generation of reactive oxygen species but no block in ATP generation.

• Permeabilization of the inner membrane to compounds that are usually not able to traverse the membrane.

Metachromatic leukodystrophy (MLD) is caused by a deficiency of arylsulfatase A and affects the CNS. MLD is

• a lysosomal storage disorder

• a disease due to dysfunctional mitochondria.

• caused by loss of the myelin sheath

• caused by a defect in proteins of the nuclear envelope

Which one of the following statements is NOT true?

• Beta-oxidation of long chain fatty acids occurs in mitochondria.

• Fatty acid biosynthesis occurs in peroxisomes.

• Peroxisomes utilize H₂O₂ to oxidize a variety of substrates.

• Peroxisomes import their repertoire of proteins using sorting signals.

Which one of the following pairs is NOT matched correctly?

• Glycocalyx - adherence

• Fimbriae - motility

• Pili - conjugation

• Peptidoglycan - cell wall

Filtration slits are formed by

• podocytes

• endothelial cells of capillary

• mesangial cells

• Lacis cells

Which one of the following vitamins is NOT absorbed in the small intestine by Na⁺-co-transporters?

• Thiamine

• Riboflavin

• Folic acid

• Ascorbic acid

A lac^- culture of E. coli was mutagenized. On what media would one spread the mutagenized to select for lac⁺ cells?

• Minimal media + lactose

• Rich media + lactose

• Minimal media + glycerol + IPTG + X-gal

• Rich media + IPTG + X-gal

Which of the following is NOT true for the Anammox bacteria?

• They convert nitrate and ammonium into dinitrogen.

• They are responsible for 30 - 50% of the dinitrogen gas produced in the ocean.

• They belong to the bacterial phylum Planctomycetes.

• Membranes of these bacteria contain ladderane lipids.

Membrane potential in mitochondria is critical for oxidative phosphorylation and is monitored by

• patch clamping

• measuring internal sodium ions after lysing the mitochondria.

• measuring the distribution of labeled ions across the mitochondrial membrane.

• measuring the consumption of ATP.