A culture medium contains two carbon sources, one is preferred carbon source (glucose) and the second is a non-preferred source (lactose).

Which one below is correct regarding the nature of growth curve of E. coli cultured in this medium?

• The growth curve will be same as when grown in presence of only glucose.

• The growth curve will be the same as when grown in the presence of only lactose.

• A lag phase will be observed between the two exponential phases.

• Two lag phases will be observed between the two exponential phases.

A practical class was going on where the students were demonstrating ATP synthesis in vitro using active mitochondria. Some students added one of the following to their tubes.

A. Dinitrophenol (DNP), an uncoupler.

B. Mild acidification of the medium.

C. Glutilferone, that permeabilized both the membranes.

D. An outer membrane permeable H⁺ quencher compound, Elila.

In which one of the above, ATP synthesis will be detected?

• A

• B

• C

• D

Membrane proteins are synthesized on endoplasmic reticulum and transported to various organelle membranes. One hypothesis for membrane protein sorting is hydrophobicity matching i.e. the proteins with a shorter transmembrane portion would partition into thinner membranes.

You are given the following three observations.

A. It was found that transmembrane portions of proteins in Golgi membranes are shorter than those in plasma membranes.

B. Presence of cholesterol increases the thickness of the bilayer.

C. The phospholipid composition of Golgi and plasma membranes are same.

Which one of the following statements is correct?

• Proteins in plasma membrane have longer transmembrane portion than proteins in Golgi membranes.

• Proteins in Golgi membranes have longer transmembrane portion than proteins in plasma membranes.

• Proteins of both Golgi and plasma membranes have same length of transmembrane protion.

• Cholesterol is more in Golgi membrane than in the plasma membrane.

A gene expressing a 50 kDa protein from an eukaryote was cloned in an E. coli plasmid under the lac promoter and operator. Upon addition of IPTG, the 50 kDa protein was not detected. Which one of the following explains the above observation?

• The cloned sequence lacked the Kozak sequence.

• E. coli does not make proteins larger than 40 kDa.

• Differences in codon preference.

• 50 kDa protein contains a nuclear localization signal.

In a heterozygous individual for a given gene, if a crossing over has occurred between the gene locus and the centromere of the chromosome, the segregation of the two alleles of the given gene will occur during meiosis at 

• either anaphase I or anaphase II

• anaphase I only

• anaphase II only

• both anaphase I and II

The photosynthetic assimilation of atmospheric CO₂ by leaves yield sucrose and starch as end products of two gluconeogenic pathways that are physically separated. Which one of the following combinations of cell organelles are involved in such physical separation of the process?

• Sucrose in cytosol and starch in mitochondria.

• Sucrose in chloroplasts and starch in cytosol

• Sucrose in mitochondria and starch in cytosol

• Sucrose in cytosol and starch in chloroplasts.

In eukaryotic replication, helicase loading occurs at all replicators during

• G₀ phase

• G₁ phase

• S phase

• G₂ phase

108.

Given below are events in the cell cycle.

(a) Phosphorylation of lamin A, B, and C.

(b) Phosphorylation of Rb (Retinoblastoma protein).

(c) Polyubiquitination of securin.

(d) Association of inner nuclear membrane proteins and 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?

• a → b → c → d

• b → c → d → a

• c → a → b → d

• b → a → c → d

Glycophorin having one highly hydrophobic domain is able to span a phospholipid bilayer membrane only

• once

• twice

• thrice

• four times

It takes 40 minutes for a typical E. coli 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 37°C in complex medium?

• 20 minutes

• 40 minutes

• 60 minutes

• 30 minutes