Which of the following statements about the genetic code is true?
A) the first position of a codon determines the amino acid
B) an amino acid can be specified for by more than one codon
C) nonsense codons contain no information
D) because DNA only contains three letters there are very few possible genes that can exist

Question

Quizplus · Accepted Answer

There are 64 possible codons, but only 20 amino acids. Therefore, some amino acids are specified by more than one codon. For example, both the codons UUU and UUC specify the amino acid phenylalanine.

A) This statement is incorrect. The genetic code is degenerate, meaning that more than one codon can specify the same amino acid. 
C) This statement is incorrect. Nonsense codons, also known as stop codons, signal the end of a protein sequence and do contain information. 
D) This statement is incorrect. DNA contains four different nucleotides, meaning there are 64 possible codons (4x4x4) and therefore a vast number of possible genes.

Which of the Following Statements About the Genetic Code Is