Silent mutation and third position

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Discussion Overview

The discussion revolves around the nature of silent mutations in genetic coding, specifically addressing why they are often associated with changes in the third position of a codon. Participants explore the implications of these mutations in the context of translation and codon recognition.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that silent mutations are more common at the third position of a codon, referencing the role of tRNAs in recognizing codons during translation.
  • One participant notes that silent mutations do not always affect the third position, indicating that while they are more frequent there, this is not an absolute rule.
  • Another participant explains that the first two bases of a codon are critical for specifying the amino acid, implying that changes in these positions would not be silent.
  • Search keywords like "wobble base" are recommended for further exploration of the topic.

Areas of Agreement / Disagreement

Participants express differing views on whether silent mutations exclusively affect the third position, with some agreeing that they are more common there while others assert that this is not a strict rule. The discussion remains unresolved regarding the absolute nature of silent mutations.

Contextual Notes

Participants acknowledge a need for further research and clarification on the mechanisms of codon recognition and the implications of silent mutations.

TytoAlba95
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I got this question in an exam. Why do silent mutations always affect the third position of a codon? I have no clue about it.
 
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SanjuktaGhosh said:
I got this question in an exam. Why do silent mutations always affect the third position of a codon? I have no clue about it.

A quick google gave me some information on this, have you had a look?
 
They don't always affect the third position, but they are definitely more common at the third position. Read up on how tRNAs recognize codons during translation.
 
The search keywords "wobble base" might help.
 
I'm sorry I didn't do my research properly before posting this question. @pinball1970

Thanks to both of you. @JonMoulton & @Ygggdrasil

I'll soon reply with an answer.
 
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SanjuktaGhosh said:
I got this question in an exam. Why do silent mutations always affect the third position of a codon? I have no clue about it.
Because the first two bases are necessary to specify the type of amino acid to be encoded. And they are both the same base. It wouldn't be silent if it was one of the first two bases because then it would be deleterious. Only the third base can change and you can still encode the same amino acid.
 

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