AP BIOLOGY

Detailed explanation-1: -The genetic code includes 64 possible permutations, or combinations, of three-letter nucleotide sequences that can be made from the four nucleotides. Of the 64 codons, 61 represent amino acids, and three are stop signals.

Detailed explanation-2: -There are 64 colons as genetic code is triplet. Three adjacent bases, termed a codon specify one amino acid. This can only account for the 20 amino acids. Thus in a triplet codon, the four bases would specify a total of 64 amino acids.

Detailed explanation-3: -Of all the 64 codons, three are known as termination codons or stop codons, which do not code for any amino acid.

Detailed explanation-4: -Three nucleotides in a row on a DNA strand is therefore referred to as a codon. Because DNA consists of four different bases, and because there are three bases in a codon, and because 4 * 4 * 4 = 64, there are 64 possible patterns for a codon.

Detailed explanation-5: -The number of potential triplets is 64. Subtracting for a necessary stop codon, organisms could code for up to 63 different amino acids. One could argue that 20 is simply good enough, but several species use up to 22 residues to synthesize proteins.