Question

Need help so bad. plz help me!

1. If the DNA sequence TCA had a one base substitution to make it TAA, which statement best describes how it would affect the protein?

A.Even though one letter changed, the same amino acid would still come in, so the protein wouldn't be altered.

B.Even though one letter changed, and one amino acid changed, the color of the amino acid stayed the same. Therefore the protein's shape would not be altered.

C.One letter changed and now instead of it being a white hydrophilic amino acid it is a yellow hydrophobic amino acid. This would cause the folding of the protein to alter as the yellow amino acid would force its way to the center of the protein.

D.One letter changed and that would alter the entire reading frame of the protein and it would be so messed up a protein wouldn't even form.

Answer 1

Option (C).

Step-by-step explanation:

Instructions for the protein synthesis is present in DNA strand, which is transferred to mRNA by the process of transcription. During transcription, DNA sequence TCA will AGU, while DNA sequence TAA will give AUU codons in mRNA.

Codon AGU codes for serine, which is a hydrophilic amino acid, while codon AUU codes for isoleucine, which is a hydrophobic amino acid.

Due to this single-base substitution in DNA, the resulting mRNA will code for a different amino acid. As amino acid sequence of protein is responsible for its proper folding and functioning, the resulting protein will show an altered protein.

During protein folding, the hydrophilic amino acids are present at the surface of proteins, while hydrophobic amino acids are present at the center of proteins. So, the substituted amino acid, which is hydrophobic in nature will force its way to the core of the protein.

Thus, the correct answer is option (C).

Answer 2

The right answer is C.

When transcribing the TCA and TAA DNA, this gives respectively AGU and AUU.

AGU encodes a serine, which is a hydrophilic amino acid.

AUU encodes a hydrophobic amino acid which is isoleucine.

If we change the TCA codon to TAA, we will have serine change by isoleucine, so it is clear that the conformation of the protein will change.