Retrovirus life cycle - enzyme contribution

[Marnoona]

---

Members don't see this ad.

Hello, i just came across this question in the AMCC official guide to the MCAT book, and I didn't quite understand the right answer for the question, if anyone could please explain the phenomena of the viral life cycle, i'd really appreciate it.

The question is:

The host cell is LEAST likely to contribute which of the following enzymes or enzymatic complexes to the retroviral life cycle?
A. Ribosomes
B. DNA-dependent RNA polymerase
C. RNA-dependent DNA polymerase
D. DNA-dependent DNA polymerase
The right answer is: C. RNA-dependent DNA polymerase.

I can't be able to understand the link between RNA being dependent on DNA polymerase in a retrovirus. What is the most enzyme contribution?

Thank you.

 

[ClemsonFirst]

DNA replication and RNA transcription all occur in the host cell from the cell's DNA. Therefore, they are DNA-Dependent, allowing us to cross out B and D becuase the cell will contribute these enzymes. Protein synthesis in the cell occurs on ribosomes, so the cell will contribute these as well allowing us to ignore A. This leaves us with C.

The RNA-dependent DNA polymerase allows the retrovirus to function properly through creating DNA from the virus's RNA. This process does not naturally occur in most host cells, so the host cell will not contribute this enzyme.

 

[Marnoona]

DNA replication and RNA transcription all occur in the host cell from the cell's DNA. Therefore, they are DNA-Dependent, allowing us to cross out B and D becuase the cell will contribute these enzymes. Protein synthesis in the cell occurs on ribosomes, so the cell will contribute these as well allowing us to ignore A. This leaves us with C.

The RNA-dependent DNA polymerase allows the retrovirus to function properly through creating DNA from the virus's RNA. This process does not naturally occur in most host cells, so the host cell will not contribute this enzyme.

Thank you very much. Now it's clear 🙂.

 

[Bomikepa]

yep! another similar way is this: I thought okay, what my body gives least to a retrovirus

ribosome- well they are part of almsot everything so its possible they could be given.

for B- okay well that is saying i make RNA from DNA, does that happen? Ofcouse in transcription. So its a possibility

for C - make DNA from RNA- does that happen in us? Umm not that i know of..it goes against the DNA--> RNA-->protein central dogma

doesn't sound like i do anything like that so i doubt this could be a possibility for me to give to a virus

for D)- make DNA from DNA- well thats how we do DNA replication so i guess that possible

so c is least likely