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TLS Online TPP Program

#Question id: 13142

The Norway rat (Rattus Norvegicus), a widespread pest, was controlled for about a decade by the anticoagulant warfarin. This chemical substance, placed in food pellets, is absorbed by the intestinal tract and inhibits the clotting of blood. After a population decline for about 10 years, rat populations increased and stabilized. In one European population, as illustrated in the graph below, the percentage of rats resistant to warfarin has remained fairly stable over a number of years.

Resistance to warfarin is governed by a dominant autosomal gene, R. More than 15 percent of the resistant animals are heterozygous at this locus (Rr). The table below indicates the response to warfarin and relative reproductive fitness of individuals that are homozygous or heterozygous for the dominant gene (R). The RR individuals have a 20-fold increase in vitamin K requirement over individuals.

Fitness is a measure of the reproductive success of a particular genotype. The highest fitness is 1.00.
There is a substantial number of heterozygotes in the population. Which of the following is the best explanation of this observation?

#Unit 10. Ecological Principles
  1. Heterozygotes (Rr) have a selective advantage over both homozygotes (RR and rr). 
  2. The gene for susceptibility (r) is increasing rapidly each generation.
  3. The gene for susceptibility (r) is being lost by chance each generation.
  4. Dominant homozygotes (RR) enjoy a reproductive advantage over heterozygotes
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TLS Online TPP Program

#Question id: 4285

#Unit 3. Fundamental Processes

VSV G protein has been a very useful tracker protein for both living cell and in vitro assays because
TLS Online TPP Program

#Question id: 4286

#Unit 3. Fundamental Processes

Transport vesicles

a. can have a clathrin coat.     b. can be coated with a heteromeric COPI and COPII coat.

c. can contain assembly proteins.

d. can shuttle proteins from mitochondria to the endoplasmic reticulum.

e. can fuse with target organelles.
TLS Online TPP Program

#Question id: 4287

#Unit 3. Fundamental Processes

How the mTOR pathway increases the protein synthesis?
TLS Online TPP Program

#Question id: 4288

#Unit 3. Fundamental Processes

During eukaryotic protein synthesis, stress conditions result in activation of specific kinases leading to phosphorylation of a key translation initiation factor that inhibits protein synthesis from a large number of cellular mRNA. Which one of the following factors is the kinase?
TLS Online TPP Program

#Question id: 4289

#Unit 3. Fundamental Processes

Match the Following

A. fidelity of codon recognition

1. involves two adjacent adenine residues in the 16S rRNA component located

within the A-site of the small subunit. These bases form hydrogen bonds with

the minor groove of each correct base pair formed between the anticodon and

the first two bases of the codon in the A-site

B. kinetic selectivity

2. Even a single mismatch in the codon–anticodon base pairing alters the position of EF-Tu, reducing its ability to interact with the factor-binding center. This, in turn, leads to a dramatic reduction in EF-Tu GTPase activity

C. Accommodation

3. When the charged tRNA is first introduced

into the A-site in a complex with EF-Tu-GTP, its 30 end is distant from the site of peptide-bond formation. To participate successfully in the peptidyl transferase reaction, the tRNA must rotate into the peptidyl transferase center of the large subunit in a process

TLS Online TPP Program

#Question id: 4290

#Unit 3. Fundamental Processes

23S rRNA catalyze peptide-bond formation explained by the model of proton shuttle given in figure.

 Which of the following statements is/are CORRECT for this model?

A. Base pairing between the 23S rRNA and the CCA ends of the tRNAs in the A- and P-sites positions is crucial for this reaction

B. This catalytic mechanism involves entropy

C. 2’-OH of the P-site tRNA act as part of a “proton shuttle”

D. it is a protein that catalyses peptide bond formation