Question

Eukaryotic mRNA is modified during and after transcription. Which end of the mRNA is shown on this page and what is the common name for this structure? What is the name of this base (see arrow) and how is it connected to the remaining part of the structure? H3 9% HN H2N Base OH OH OH он он What other DNA modification exist in eukaryotes? Question 12 (6 points) Can the nucleotide sequence of an mRNA be predicted from the amino acid sequence of its polypeptide product? Why or why not? Page 11 of 15

Answer 1

12) Answer

No, we cannot predict the nucleotide sequence of an mRNA from amino acid sequence of its polypeptide product.

Genetic code is degenerate which means multiple codons can be used for one amino acid.

The DNA to amino acids coding is redundant which means that some amino acids coded by multiple codons. Codons are sets of 3 nucleotides.

But if we know the sequence of a gene then we predict the amino acid of a protein

Example:

Amino acid serine can be coded for by a UCA, UCC, UCU, or UCG. These codons are different only in last nucleotide. Thus, here we notice that these are minor mutations in DNA. If we consider UCA, and A mutated into G. Then we see it will code for serine only. This is called as silent mutation as it does not affect the protein production.

To find Arg there are 6 different codons that can be used. But we do not know what is sequence on gene. There are multiple possibilities (6 possibilities).