AP BIOLOGY

Detailed explanation-1: -A codon is a DNA or RNA sequence of three nucleotides (a trinucleotide) that forms a unit of genomic information encoding a particular amino acid or signaling the termination of protein synthesis (stop signals).

Detailed explanation-2: -Multiple codons can code for the same amino acid. The codons are written 5’ to 3’, as they appear in the mRNA. AUG is an initiation codon; UAA, UAG, and UGA are termination (stop) codons.

Detailed explanation-3: -There are 3 STOP codons in the genetic code-UAG, UAA, and UGA. These codons signal the end of the polypeptide chain during translation. These codons are also known as nonsense codons or termination codons as they do not code for an amino acid.

Detailed explanation-4: -Answer and Explanation: Codons must consist of three nucleotides because this gives the cell the appropriate amount of combinations to code for all twenty amino acids with some redundancy. There are four possible bases in DNA. So, if each codon was only one nucleotide, we could only code for four amino acids.

Detailed explanation-5: -Three codons, UAA, UAG, and UGA, are known as stop codons as they stop the process of translation. If this is a mutation as a stop codon and its finishes prematurely it is called an amber codon. AUG is also known as a start codon, as it initiates the process of translation.