Silent mutation and third position

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SUMMARY

Silent mutations predominantly affect the third position of a codon due to the redundancy in the genetic code, where the first two bases determine the specific amino acid. Changes in these first two bases typically result in a different amino acid, leading to potential deleterious effects. The phenomenon is explained by the concept of "wobble base," which allows for variability in the third position without altering the encoded amino acid. Understanding tRNA recognition of codons during translation is crucial for grasping this topic.

PREREQUISITES
  • Basic understanding of genetic code and codons
  • Knowledge of tRNA and its role in translation
  • Familiarity with the concept of wobble base pairing
  • Understanding of silent mutations and their implications
NEXT STEPS
  • Research the concept of "wobble base" in tRNA recognition
  • Study the genetic code and its redundancy in detail
  • Explore the mechanisms of silent mutations and their biological significance
  • Learn about the implications of codon usage bias in protein synthesis
USEFUL FOR

Students studying genetics, molecular biologists, and anyone interested in the mechanisms of mutation and protein synthesis.

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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