A Researcher Has Labeled the 5? End of a DNA

question 37

Short Answer

A researcher has labeled the 5? end of a DNA primer with ³²P radioisotopes. The primer can hybridize to a complementary sequence near the 3? end of a long, spliced mRNA molecule composed of three exons. The mRNA molecule can interact with two RNA-binding proteins: one of them (protein 1) binds to the first exon and the other (protein 2) binds to the second exon. The researcher uses reverse transcriptase to extend the primer in the presence of the mRNA and either of these proteins, then separates the cDNA products by gel electrophoresis, and finally visualizes the labeled DNA bands by autoradiography. The results are presented schematically in the following drawing. Assuming that the reverse transcriptase falls off the template when confronted by bound proteins, which lane (A or B) in the gel corresponds to the reaction in the presence of protein 1? Write down A or B as your answer.

---

Definitions:

Lymphocytes

A type of white blood cell that plays a significant role in the immune response, including T cells and B cells.

Confidence Limits

Confidence limits are the lower and upper bounds of a confidence interval, suggesting the range within which the true population parameter is expected to lie with a certain level of confidence.

Interval Estimate

A range of values used to estimate a population parameter, typically constructed with a specific confidence level to contain the parameter.

Margin Of Error

An expression of the amount of random sampling error in a survey's results, indicating a range within which the true value lies with a certain level of confidence.