Practice Questions

TLS Online TPP Program

#Question id: 2887

Which of the following reasons has led to the evolutionary selection of an extra methyl group in DNA?

#Unit 2. Cellular Organization

Thymine is more stable than Uracil due to the absence of an extra methyl group attached to the 5’ position.
Cytosine undergoes spontaneous deamination to yield Uracil, which repair enzymes cannot recognize as foreign to DNA.
If the genetic material contained uracil, then uracil arising from cytosine deamination would go undetected by the surveillance systems that maintain the genome.
Uracil has greater resistance to photochemical mutation, making the genetic material more stable.

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TLS Online TPP Program

#Question id: 34174

#Unit 3. Fundamental Processes

Once bound to a primer:template junction, DNA polymerase interacts tightly with much of the double stranded portion of the DNA by

TLS Online TPP Program

#Question id: 34175

#Unit 3. Fundamental Processes

A. For processive DNA synthesis, proofreading occurs without releasing the DNA from the polymerase

B. When a mismatched base pair is present in the polymerase active site, the primer:template junction is destabilize

C. The DNA polymerase active site binds such a mismatched template poorly, but the exonuclease active site has a 10-fold higher affinity.

D. The incorrect nucleotide is removed by the 5’-3’-exonuclease nuclease activity

Choose true and false

TLS Online TPP Program

#Question id: 34176

#Unit 3. Fundamental Processes

A. The lagging strand must be synthesized in the form of Okazaki fragments.

B. Both strands are synthesized discontinuously.

C. Not all of the fragment population represents bona fide Okazaki fragments; some are pseudofragments

D. Primers start with the sequence pppAG positioned opposite the sequence 3’–GTC-5’ in the template

Choose true and false

TLS Online TPP Program

#Question id: 34177

#Unit 3. Fundamental Processes

Which of the following combination of the statements regarding polA mutants is correct

A. fail to join their Okazaki fragments

B. fail to removes the RNA primer

C. fail to removes the mismatch errors

D. fail to synthesis Okazaki fragments

TLS Online TPP Program

#Question id: 34178

#Unit 3. Fundamental Processes

A. SSBs interact with ssDNA in a sequence-independent manner.

B. SSBs primarily contact ssDNA through electrostatic interactions with the phosphate backbone and stacking interactions with the DNA bases.

C. SSBs interact with ssDNA in a sequence dependent manner via hydrogen bonds with phosphate backbone

D. SSBs shows sigmoidal behaviour of binding

Choose true and false

TLS Online TPP Program

#Question id: 34179

#Unit 3. Fundamental Processes

A. At the replication fork, the dsDNA in front of the fork becomes increasingly positively supercoiled.

B. At the replication fork, the dsDNA in front of the fork becomes increasingly negatively supercoiled.

C. The “swivelase” that prevents the accumulation of positive supercoils ahead of the replication fork.

D. The “swivelase” that prevents the accumulation of negative supercoils ahead of the replication fork.

Which of the following combination of statements is correct