Question

Coding segments of DNA contain CAC. Which amino acid is picked up during translation?
A. Leucine
B. Glutamic acid
C. Valine
D. Methionine

Answer 1

Hint: During protein synthesis, translation is the process of converting the sequence of a messenger RNA (mRNA) molecule into a sequence of amino acids. The genetic code is a description of the connection between a gene's base pair sequence and the amino acid sequence it encodes. To produce a polypeptide from the mRNA, the ribosome reads the sequence of the mRNA in groups of three bases in the cell cytoplasm.
Concept used:
To solve this question we need to first know the point that out of the two strands of DNA the strand which is complementary in sequence as m-RNA is known as the coding strand except thymine is replaced by uracil.
Thus, the sequence of coding strands of DNA can be associated as triplet codons on m-RNA and the polypeptide sequence can be guessed.

Complete answer:
Now let’s see each of the options to know the correct amino acid which is picked for CAC.
Option: A - Since for CAC the m-RNA would have GUG which as per the genetic code will code for Valine and not leucine.
So, Option A is not correct.
Option: B - Since for CAC the m-RNA would have GUG which as per the genetic code will code for Valine and not glutamic acid.
So, Option B is not correct.
Option: C - Since for CAC the m-RNA would have GUG which as per the genetic code will code for Valine.
Thus, Option C is correct.
Option: D - Since for CAC the m-RNA would have GUG which as per the genetic code will code for Valine and not methionine.

Hence, Option C. Valine is the correct answer.

Note:
The four bases of DNA—the A, C, G, and T s—are strung together in such a way that the cellular machinery, the ribosome, can read them and transform them into a protein known as genetic code. Each three nucleotides in a row counts as a triplet in the genetic code and codes for a single amino acid. During protein synthesis m-RNA sequence is transcribed from codons of DNA which are then translated into an amino acid chain in translation.