Silent mutation and third position

In summary, silent mutations typically occur at the third position of a codon because the first two bases are necessary for specifying the amino acid and changing them would result in a non-silent mutation. The third base can be changed without affecting the encoded amino acid.
  • #1
TytoAlba95
132
19
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.
 
Biology news on Phys.org
  • #2
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?
 
  • #3
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.
 
  • #4
The search keywords "wobble base" might help.
 
  • #5
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.
 
  • Like
Likes Tom.G and pinball1970
  • #6
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.
 

1. What is a silent mutation?

A silent mutation is a change in a DNA sequence that does not result in a change in the amino acid sequence of a protein. This is because the genetic code is redundant, meaning that multiple codons can code for the same amino acid.

2. What is the third position in a codon?

The third position in a codon refers to the third letter in a sequence of three nucleotides that make up a genetic code. This position is important because it determines which amino acid will be incorporated into a protein during translation.

3. How does a silent mutation affect protein structure?

A silent mutation does not affect protein structure because it does not change the amino acid sequence. However, it can still have an impact on protein function by altering the rate of protein synthesis or affecting RNA stability.

4. Can silent mutations cause disease?

Silent mutations are not typically associated with disease because they do not result in a change in protein function. However, in some cases, they may contribute to the development of certain diseases, such as cancer, by altering gene expression.

5. How are silent mutations detected?

Silent mutations can be detected through DNA sequencing, which involves determining the exact sequence of nucleotides in a DNA molecule. Bioinformatics tools can also be used to analyze DNA sequences and identify potential silent mutations.

Similar threads

Replies
4
Views
876
Replies
3
Views
898
  • Biology and Medical
Replies
15
Views
1K
Replies
4
Views
763
  • Biology and Medical
Replies
7
Views
1K
Replies
10
Views
1K
Replies
18
Views
2K
Replies
3
Views
1K
  • Biology and Medical
Replies
1
Views
2K
  • Biology and Medical
Replies
8
Views
1K
Back
Top