IMAT 2014 Q33 [Human Immunodeficiency Virus]

Past Papers Solutions Archives
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1

Which of the following molecules are associated with the Human Immunodeficiency Virus (HIV)?

  1. DNA
  2. RNA
  3. Phospholipids
  4. Reverse transcriptase

A. 1 and 2 only
B. 2 and 3 only
C. 1, 2 and 4 only
D. 1, 2, 3 and 4
E. 2, 3 and 4 only

2

The correct answer for this question is choice E.

This question requires you to be familiar with the structure of HIV, which will help you either include or eliminate choices within you consideration:

  • HIV or the human immunodeficiency virus, is part of the family retroviridae, which is a family of positive single-stranded RNA viruses. Another virus that belongs to this family is the HLTV or the human T-cell lymphotropic viruses. This then eliminates #1 from your considerations, and further strengthens that #2 is a correct association with HIV.
  • Various viruses, including viruses that belong to the retroviridae family, are surrounded by a continuous bilayer membrane with accompanying viral proteins. This bilayer configuration would not be possible if phospholipids were completely absent, thus this makes #3 as a correct association with HIV.
  • A significant contribution to the virulence of HIV are the different structural proteins that HIV has. One of which, is an important gene called the pol gene that codes for a polyprotein that includes proteases, integrases, which help insert the viral genes into the host, and the reverse transcriptase, which is an enzyme the virus family retroviridae is well known for. This enzyme converts viral RNA into dsDNA, which is the opposite of the known process of transcription, which is why it is called reverse trascriptase.

Thus knowing the basic structure of HIV, it now makes sense why the correct answer is choice E.

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3

Hi,
Why is 1. DNA considered not associated with the virus when it is produced by the virus through reverse transcriptase?

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4

it is not associated with the virus because the virus itself doesn’t contain DNA. one of the main rules of viruses is to contain either one of the nucleic acids. HIV contains RNA and then makes DNA out of it when inside of a host cell. So it does not come with the DNA in the original package :))

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5

I mean that seems to be the reasoning they expect but one would think that the use of the word “associated” implies any relation even by a long shot.

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6

that is correct I understand what you mean but what they meant with associated here is more like without any interaction with a host cell. if they wanted to long shot they would’ve probably mentioned ‘inside of a host cell’.

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