Practice Questions

TLS Online TPP Program

#Question id: 7246

Treatment of Xenopus embryos with lithium dorsalizes the embryos by interfering with cell-cell signaling pathways. What, if anything, is the effect of lithium on hydra, and what might we infer about its mechanism of action?

#Unit 5. Developmental Biology

Lithium has no effect in hydra
Lithium dorsalizes hydra just as it does Xenopus, so we would assume its mechanism of action is identical in the two organisms
Lithium causes the formation of extra basal discs, which we might infer arise through interference with cell-cell signaling pathways
Lithium causes the formation of extra head regions, since the head of hydra is mechanistically analogous to the dorsal side of Xenopus embryos

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TLS Online TPP Program

#Question id: 34172

#Unit 3. Fundamental Processes

Frameshifts occur when an extra nucleotide is inserted or omitted. Which of sequence and property is most sensitive combination for the frameshift to occur

TLS Online TPP Program

#Question id: 34173

#Unit 3. Fundamental Processes

The 3’–5’ exonucleolytic activity is found in which subunit of bacterial DNA Polymerase III

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