performs the following experiment. She wants to replicate a test strand of DNA using wildtype of Saccharomyces cerevisiae (budding yeast) and two mutants which she calls poor-rep1 and poor-rep2. She performs the experiment with her wildtype strain, and her test DNA strand replicates perfectly. She does the same experiment with poor rep-1 and discovers that this strain can only synthesize the DNA strand if she adds a purified wildtype DNA polymerase-a exogenously. When she performs the experiment with poor rep-2 she discovers that adding wildtype DNA polymerase-a has no effect. Which of the following scenarios is a possibility for the poor rep-1 and poor rep-2 strains?

Question

Biology

Braydon Valdez

13 October, 09:41

performs the following experiment. She wants to replicate a test strand of DNA using wildtype of Saccharomyces cerevisiae (budding yeast) and two mutants which she calls poor-rep1 and poor-rep2. She performs the experiment with her wildtype strain, and her test DNA strand replicates perfectly. She does the same experiment with poor rep-1 and discovers that this strain can only synthesize the DNA strand if she adds a purified wildtype DNA polymerase-a exogenously. When she performs the experiment with poor rep-2 she discovers that adding wildtype DNA polymerase-a has no effect. Which of the following scenarios is a possibility for the poor rep-1 and poor rep-2 strains?

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Answers (1)

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Jayson Carey · Answer 1

The given question is not complete the complete question is:

Ginny Genestudy performs the following experiment. She wants to replicate a test strand of DNA using wildtype of Saccharomyces cerevisiae (budding yeast) and two mutants which she calls poor-rep1 and poor-rep2. She performs the experiment with her wildtype strain, and her test DNA strand replicates perfectly. She does the same experiment with poor rep-1 and discovers that this strain can only synthesize the DNA strand if she adds a purified wildtype DNA polymerase-a exogenously. When she performs the experiment with poor rep-2 she discovers that adding wildtype DNA polymerase-a has no effect. Which of the following scenarios is a possibility for the poor rep-1 and poor rep-2 strains.

The poor rep-1 strain has a mutation in the gene that codes for either PriS or PriL but not the gene encoding polymerase-a, whereas the poor rep-2 strain has a mutation in the gene that codes for polymerase-a.

The poor rep-1 strain has a mutation in the gene that codes for PriS and polymerase-a, but not PriL, and the poor rep-2 strain has a mutation in the gene that codes for PriS or PriL but not the gene that codes polymerase-a

The poor rep-1 strain has a mutation in the gene that codes for PriL and polymerase-a, but not PriS, and the poor rep-2 strain has a mutation in the gene that codes for polymerase-a, but not PriS or PriL

The poor rep-1 strain has a mutation in the gene that codes for Pola, but not for either PriS or PriL, and the poor rep-2 strain has a mutation in the gene that codes for either PriS or PriL but not for the gene that codes for polymerase-a.

All of the above are correct

Answer:

The correct answer is statement 4th.

Explanation:

In the case of poor rep1, when the addition of DNA polymerase is done exogenously, the process of replication takes place normally. This shows that all the processes are working correctly, except for the fact that there can be some mutation in the polymerase-a gene that has resulted in the production of DNA polymerase.

However, in the other strain, that is, in poor rep 2, even after supplementing the DNA polymerase exogenously, the replication process fails, as DNA polymerase fails to give rise to the short RNA primer. The production of RNA primer takes place by DNA primase, which is encoded by a large subunit of PriL and the short subunit of PriS, and also with the assistance of helicase enzyme and denatured DNA. This shows that the strain poor rep2 must be containing some form of mutation in PriL and PriS.