Question

Start and stop codons are

• A. AUG and UGA
• B. GUA and AAA
• C. UCA and UAA
• D. GUC and AUG

Answer 1

Answer: (A)

AUG and UGA

Codons are the nucleotide base triplets that specify a particular amino acid in proteins. The codons that do not code for any amino acid and cause termination of protein synthesis are known as stop codons. The RNA stop codons are UAG, UAA and UGA. The start codon specifies the first codon of mRNA transcript that is translated by a ribosome. It codes for methionine in eukaryotes and a modified Met in prokaryotes. "AUG" is the most common start codon. AUG and UGA are start and stop codons respectively which makes option A correct. GUA and AAA code for valine and lysine which makes option B wrong. UCA codes for serine which makes option C wrong. GUC codes for valine which makes option D wrong. The correct option is A.