Question

Genetic code backwards:

You have just discovered a small neuropeptide that makes your friend have "dancing feet". Whenever they hear a certain song, they just have to dance.

As fun as it is to make them dance whenever you want, you realize that this could be a serious problem and want to help.

Since you do not have "dancing feet", you have a normal neuropetide.  

You both go to a research clinic and have the small neuropetide sequenced.

Your normal protein sequence is: MTHKRSVV while your friend's protein sequence is: MTHRRSVV.

Answer the following questions:

1) Based on the protein sequence, construct a potential mRNA and also the associated double stranded DNA for both you and your friend. ( write all the molecules out and give the correct 5'---3' orientations for the RNA/DNA and the C-/N-terminals for the protein and use ALL CAPITAL LETTERS)

2) There is a difference between the amino acids. Determine the point mutation (for the double stranded DNA molecule) that changes between the DNA sequences from you and your friend and list out the altered sequence and how that would change the codon from one amino acid to the other.

Answer 1

1- DNA sequence of the peptide

Potential mRNA for MTHKRSVV

aug acc cau aaa cgc agc gug gug

5' atg acc cat aaa cgc agc gtg gtg 3'

3' tac tgg gta ttt gcg tcg cac cac 5'

N-terminal - MTHKRSVV C- terminal

Potential mRNA for MTHRRSVV

aug acc cau aga cgc agc gug gug

DNA sequence for MTHRRSVV peptide

5' atg acc cat aga cgc agc gtg gtg 3'

3' tac tgg gta tct gcg tcg cac cac 5'

N-terminal - MTHRRSVV C- terminal

2- There is transition mutation where A is mutated into G.

Codon AAA is changed into AGA

AAA codes for Lysine and ATA codes for arginine