Return to MCAT® Blog Homepage

MCAT Biology Question — Viruses

While viruses are incredibly simple structures composed of little more than a protein coat and some DNA, some viruses require enzymes to be packaged in with their genetic material. Human immunodeficiency virus (HIV) is an example of a retrovirus. In HIV, which of the following proteins must be packaged in with its nucleic acids in order to reproduce successfully?

 

A. DNA polymerase

B. Helicase

C. Reverse transcriptase

D. None of the above; HIV can utilize its host cell for all of the proteins or enzymes it needs.

Click for Explanation

C is correct. A retrovirus is a single-stranded RNA virus that is able to convert its RNA to DNA with the help of the enzyme reverse transcriptase.

A. DNA polymerase, incorrect, DNA polymerase is the enzyme that builds the new DNA strand during replication in the nucleus. HIV does not have any particular need for DNA polymerase, and in any case, the host cell contains this enzyme.

B. helicase, incorrect, helicase is the enzyme that unwinds the DNA double helix for replication. This choice is incorrect for a similar reason as choice A.

C. reverse transcriptase, correct.

D. incorrect. While this choice is tempting, note that HIV infects human cells. Human cells typically do not create DNA from RNA, so they would not be expected to contain reverse transcriptase. This enzyme, then, must be provided by HIV itself.

Want more MCAT practice?

We’ve got options for every schedule and learning style!

From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!

Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.

Create your Free Account to access our MCAT Flashcards SIGN UP NOW
MCAT is a registered trademark of the Association of American Medical Colleges (AAMC), which is not affiliated with Blueprint.