Which of the following would inhibit mRNA synthesis?

[MedPR]

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Which of the following would inhibit mRNA synthesis?

I. a nonsense mutation
II. a mutation in DNA Polymerase III which prevents binding to DNA
III. loss of the promoter region


A III only
B I and III only
C I and II only
D I, II, and III

Explanation: The key to answering this question is understanding how the process of transcription and translation occur from DNA through to protein. A nonsense mutation will be present on the DNA and will be transcribed into mRNA; the nonsense mutation will inhibit protein synthesis but it will not affect transcription of the DNA to mRNA. A mutation in DNA Pol III would inhibit DNA replication but not affect the process of transcription or translation. Of the three options, only loss of the promoter would inhibit mRNA synthesis because the promoter is signal to RNA Polymerase to bind and transcribe mRNA.

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If you inhibit DNA replication, don't you indirectly inhibit mRNA transcription?

 

[chiddler]

If you inhibit DNA replication, don't you indirectly inhibit mRNA transcription?[/QUOTE]

No. If you completely disable DNA replication for a cell, all you have done is prevent it from undergoing mitosis.

Answer is the third one only.

 

[MedPR]

If you inhibit DNA replication, don't you indirectly inhibit mRNA transcription?

No. If you completely disable DNA replication for a cell, all you have done is prevent it from undergoing mitosis.

Answer is the third one only.[/QUOTE]

In an extreme case where one stopped replicating DNA, wouldn't they eventually run out of DNA to transcribe to mRNA?

 

[Ssina]

No. If you completely disable DNA replication for a cell, all you have done is prevent it from undergoing mitosis.

Answer is the third one only.

In an extreme case where one stopped replicating DNA, wouldn't they eventually run out of DNA to transcribe to mRNA?[/QUOTE]

not really a cell arrested at G0 doesn't need to replicate anymore but uses RNA pol to transcribe still, like a neuron.

 

[MedPR]

In an extreme case where one stopped replicating DNA, wouldn't they eventually run out of DNA to transcribe to mRNA?

not really a cell arrested at G0 doesn't need to replicate anymore but uses RNA pol to transcribe still, like a neuron.[/QUOTE]

Oh that's right. For some reason I was locked in thinking that "you need to keep replicating DNA so the cell can transcribe it to mRNA. No DNA = no RNA"