The following is a segment of the template strand of human BRCA1 gene:
TGG AAT TAT CTG CTC TTC GCG
c. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?

Question

The following is a segment of the template strand of human BRCA1 gene:

TGG AAT TAT CTG CTC TTC GCG

c. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?

Accepted Answer

Hi, everybody. Our next problem says, consider a segment of the non coding strand. AC cggtctag ac TT AC GT, if G replaces the second nucleotide in the third codon, determine the change in the amino acid sequence if there is any. So we need to think this through here. First of all, we know we're dealing with DNA since we have thiamine residues in here, the DNA and we're dealing with a non coding strand. So another name for the non coding strand is the template strand. So we always have to keep straight. Which strand of DNA are we talking about? The coding strand gets its name from the fact that since it's not the template, it's complementary to the template strand just as the MRN A is complementary, so they will have the same bases in the same order with the exception that they'll be used in the MRN A. Everywhere, there's a T in the coding strand of the DNA, but we have the non coding or template strand. So we need to remember that it will be complimentary to our MRN A. So let's divide our given strand into three letter codons. So we start with AC C. So then this dividing line there, GGT and CT A and we know we're talking about the second nucleotide in the third codon. So our third coon if we live 123 is CT A and that's the non coding strand. So to find out what amino acid we're talking about, we would need to look at the MRN A transcript. So we need the complimentary basis. So complimentary to C, we have G and then K Bry to T we have A and then complimentary to A will be, since we're talking about Mrnau, again, not a DNA strand. Now we're talking about the MRN A. So this is going to be our MRN A coon from which we can deduce which amino acid does this code for. And if we look it up on a chart of codons, so when we look up gau on a code on chart, we'll see that, that codes for the amino acid A sp or aspartic acid. Now, when we made this change, so we'll label this as the old strand. So when we made the change is as if G replaces the second nucleotide and third coon. So we've got our third coat on. So it was CT A, we were going to replace the second one. So our new code on will be CG A. So well, that new, so if that's our DNA template strand, so the one that MRN A is made from then our MRN A strand. Complimentary to C is G, complimentary to G is C and then complimentary to A is T except we're an MRN A. It's not going to be A T, it's going to be A U. So we've gone from Gau and the old version to GC. So that's our code on, go to our code on chart. What is GCU? Well, that is alanine. So it changed that amino acid. That's the third amino acid in this sequence here. So our mutation with replacing, taking G and using that to replace the second nucleotide and the third codon, the change in the amino acid sequence is so that third amino acid in the peptide gets changed from aspartic acid to alanine. See you in the next video.

The following is a segment of the template strand of human BRCA1 gene:
TGG AAT TAT CTG CTC TTC GCG
c. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?

Verified video answer for a similar problem:

Key Concepts

DNA Structure and Function

Point Mutation

Amino Acid Codons

The following is a segment of the template strand of human BRCA1 gene:TGG AAT TAT CTG CTC TTC GCGc. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?

Verified video answer for a similar problem:

Key Concepts

DNA Structure and Function

Point Mutation

Amino Acid Codons

The following is a segment of the template strand of human BRCA1 gene:
TGG AAT TAT CTG CTC TTC GCG
c. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?