Question

use the following table to answer the question
codons found in messenger rna
this table shows the codons found in messenger rna. using this information, what sequence of nucleotides in the template strand of dna would code for the polypeptide sequence val - asp - ser?
a guu - gau - agc
b caa - cta - tcg
c gtt - gat - agc
d caa - cua - ucg

Explanation:

Step1: Recall DNA - RNA base - pairing rules

DNA has bases A, T, C, G and RNA has bases A, U, C, G. The base - pairing rules are A - U (in RNA - DNA interactions), T - A, C - G and G - C. First, we need to find the mRNA codons for the amino - acids and then find the complementary DNA template strand.

Step2: Find mRNA codons for amino - acids

From the table, for Val (Valine), possible mRNA codons are GUU, GUC, GUA, GUG. For Asp (Aspartic acid), possible mRNA codons are GAU, GAC. For Ser (Serine), possible mRNA codons are UCU, UCC, UCA, UCG, AGU, AGC. Let's assume the mRNA codons are GUU - GAU - AGC for this case.

Step3: Find the complementary DNA template strand

Using the base - pairing rules (A - U, T - A, C - G, G - C), if the mRNA sequence is GUU - GAU - AGC, the complementary DNA template strand sequence will be CAA - CTA - TCG.

Answer:

B. CAA - CTA - TCG