Question

a piece of eukaryotic DNA is shown below:                     

^5’- CACTCACCCGATTTTTGAATGCCGCTGATGAATCTCTGGTAA -^3’

A) WHAT IS THE mRNA PRODCUED, IF THIS IS THE CODING STRAND?

b)Assuming that after processing, a cap is added to the mRNA at the 5’ end, predict the amino-acid sequence of the protein produced from this piece of mRNA using SINGLE LETTER codes. In your answer denote both the amino and carboxy ends of the protein?

THANKS FOR THE HELP.

Answer 1

A) Coding strand refers to the DNA strand whose nucleotides corresponds to the base sequence of mRNA produced and in the mRNA uracil is present in place of thymine. So in our case the mRNA is

5^' - CACUCACCCGAUUUUUGA AUG CCGCUGAUGAAUCUCUGGUAA - 3^' .

B) The amino acid sequence of the protein produced from the mRNA is 5^'- M P L M I L W -3^' ( methionine proline leucine methionine isoleucine leucine tryptophan ) because amino acid is always transcribed from the first initiation codon encountered and in our case nucleotide number 18, 19, 20 i.e., AUG from the 5^' end represents the initiation codon. The amino acid end is the 5^' end and the carboxy end is the 3^' end of the protein.