What mRNA sequence does the following template DNA nucleotide sequence specify?
5’TTTTAGCTTTTTGGCATCA3′
Answer: 5’UGAUGCAAAAAGCUAAAA3′
What is the small protein sequence that will result from the mRNA that is made in the question above?
a) phe-stop-leu-phe-gly-ile
b) met-pro-lys-ser
c) lys-ile-glu-lys-pro
d) thr-thr-cal-pre-arg-phe
Answer
Answer c) lys-ile-glu-lys-pro
5’UGAUGCAAAAAGCUAAAA3′ we translate from the 3′ end towards 5′ end
The protein sequence could be lys-ile-glu-lys-pro-Ser
The shorter sequence should then be lys-ile-glu-lys-pro
Explanation
It is first important to note that each codon consists of three nucleotides, usually corresponding to a single amino acid.
The template DNA is first transcribed in that A is substituted with U and G substituted with C to form the corresponding mRNA which is 5’UGAUGCAAAAAGCUAAAA3′
We divide the mRNA into sections of three nucleotides and then find the amino acid for each codon as follows
5’UGA-UGC-AAA-AAG-CUA-AAA3′
We start from the 3′ end
AAA – Lys
AUC – ile
GAA – Glu
AAA -Lys
CGU -Pro
AGU – Ser
The protein sequence is c) lys-ile-glu-lys-pro