Sequence piece of mRNA....2 questions....?

Question

This is the sequence of a pierce of mRNA. Can you please help me answer the following questions?? Thanks!!

5' AUG GGC UUC CAG GAC GGU CGG 3'

1. Describe what would happen to the protein product of this piece of mRNA if the C in third codon (UUC) was changed to a U. and What type of MUTATION would this be?

2. If the same C (3rd codon in UUC) were deleted? and what type of MUTATION is this?

thanks so much!!!

Answer 1

1) tranversion

2) deletion

Answer 2

1. UUC codes for phenylalanine and UUU codes also for phenylalanine. So in this case the final protein would remain the same, because both UUC and UUU would lead to the attachment of the same amino acid. This is example of point mutation (substitution of one nucleotide) and also called silent mutation because it leads to attachment of same amino acid.

2. When C in UUC would be deleted, than all the nucleotides would shift over by one which would change the whole codon triplets and lead to change most (if not all) amino acids following this UU- codon. So the whole final protein would we changed because the building blocks (amino acids) are changed. This is and example of deletion. Because this deletion is of only one nucleotide (not 3, which would eliminate the whole amino acid and leave the rest intact) and causes shift in the nucleotides, it is also called frameshift mutation.

original mRNA was

AUG GGC UUC CAG GAC GGU CGG

protein:

methionine- glycine-phenylalanine-

glutamine-aspartate-glycine-arginine

new mRNA after deletion:

AUG GGC UUC AGG ACG GUC GG

protein:

methionine-glycine-phenylalanine-

arginine-threonine-valine-GG

GG is which is incomplete codon

and would in this case stop translation

Answer 3

the first mutation is a point mutation -- nothing would happen to the protein product because uuc and uuu both code for the same amino acid -- phenylalanine. -- because the amino acid is unchanged, this could also be called a silent mutation (a point mutation can be a silent mutation, but not all point mutations are silent)

the second is a frame shift mutation -- although the third amino acid would remain unchanged, uuc -- uuc, most of the rest of the amino acids would be changed, from the 4th codon on, you now have

AGG ACG GUC GG 3'

Answer 4

1. single-base  - produce an altered amino acid in the protein product

2. frame shift mutation