Question

Which of the following is known as universal codon?

• A. AAA
• B. CCC
• C. GGG
• D. UUU

Hint:

Recall which codon was decoded first, via the poly-U experiment.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Nirenberg and Matthaei's classic poly-U experiment (1961) used a synthetic RNA made only of uracil (UUUUU...) in a cell-free translation system to crack the very first codon of the genetic code.

Step 2: Identifying the Codon:
This experiment showed that the codon UUU codes for the amino acid phenylalanine, and because it was the first codon deciphered and is used with near-universal consistency across organisms, UUU is referred to as the universal codon.