Would a frame shift mutation have a more serious effect if it occured near the beginning of a gene or the....?

Question

Would a frame shift mutation have a more serious effect if it occured near the beginning of a gene or the end of a gene? Explain your answer.

this is what i put: It would have a more serious effect if it occured near the beginning of a gene because it will prevent a number of codons from coding for the proper amino acids.

my teacher said i needed to explain it though. i thought i did but i guess i didnt. please help me on this though.

explain your answer in no more than 2 sentences please, because my teacher likes the answers short and brief. thanks!

Answer 1

I think you had a very good answer for the teacher, and I'm a Molecular Biologist.

Perhaps if you had said that there would be MORE codons altered by an upstream frameshift mutation than one occurring downstream.

Also a frameshift mutation could easily (and probably would) result in the premature termination of the peptide chain by randomly creating a stop codon.

Answer 2

Well think about what Frameshift means.

Say you have the sequence of bases:

AGCTCTATCG

removing the first "G", at the beginning, would give:

ACTCTATCG

Since three bases (a codon) code for one amino acid, you would have the transcription/translation of completely different amino acids: NO CORRECT AMINO ACIDS WOULD BE TRANSLATED!

But say that instead of the frameshift mutation occurring at the beginning, it was the last cytosine "C"

AGCTCTATG

Notice that the first two codons (AGC,TCT) are correct even though the deletion of "C" caused a frameshift mutation at the end. In effect, we still have a frameshift mutation, but because it happened at the end of the sequence, it affects fewer codons and therefore amino acids.

Answer 3

Downstream of the frame shift, every codon is changed. Therefore, every amino acid downstream of the frame shift is at risk of being abnormal.

Best wishes and good luck.

Answer 4

if it's at the begining of the gene, then ALL of the rest of the codons would be shifted. if it's at the end of the gene, the entire begining of the gene is fine.