Question

When students attempted to duplicate Hershey and Chase's experiment, they injected a host cell with radioactive DNA from a T2 phage and measured radioactivity in the host cell's descendants. Why was the students' experimental design flawed?

The DNA should have been labeled with fluorescent dye instead of radiation.
The radioactive DNA should have been incubated before it was injected in the host cell.
The students did not test both components of the phage as candidates for the heritable material.
The students should have taken the DNA from a T4 phage instead of a T2 phage.

Answer 1

I am guessing that it is the third answer, as it makes the most sense to me. The rest I believe are not correct.

Answer 2

@aaronq

Answer 3

um the first 2 answers dont really make much sense.. and the last wouldn't make much of difference (although i'm dont know too much about virology).

so by process of elimination i would also say that C is the right answer

Answer 4

though i dont know what they mean by "both components"

Answer 5

@aaronq @greatmath678 The experiment was to see if protein or DNA was the unit of heritability and genetic instruction. Since there is lots of P in DNA and no S, and lots of S in proteins and little or no P, you would inject labelled DNA and labelled S and see which of the labelled atoms occurred in the offspring.

"both components" is a reference to the original study. By not telling you the second unnamed component the question is able to check for two things: you are fully aware of how the Hershey-Chase experiment was designed and exactly how it worked to provide an answer to the DNA vs. protein question.

Answer 6

hmmmm i see. I wouldn't call a radioactive label "a component", but i guess they gotta test your "knowledge" somehow. Multiple choice is the worst type of testing.

Answer 7

Are you in ap bio?