AP BIOLOGY

Detailed explanation-1: -A codon is a sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis. DNA and RNA molecules are written in a language of four nucleotides; meanwhile, the language of proteins includes 20 amino acids.

Detailed explanation-2: -Simple math showed that only 16 words are possible from a two-letter combination, but a three-letter code produces 64 words. Operating on the principle that the simplest solution is often correct, researchers assumed a three-letter code called a codon.

Detailed explanation-3: -Each 3-letter DNA sequence, or codon, encodes a specific amino acid. The code has several key features: All protein-coding regions begin with the “start” codon, ATG. There are three “stop” codons that mark the end of the protein-coding region.

Detailed explanation-4: -This sequence is broken into a series of three-nucleotide units known as codons (Figure 1). The three-letter nature of codons means that the four nucleotides found in mRNA-A, U, G, and C-can produce a total of 64 different combinations.

Detailed explanation-5: -DNA and the corresponding messenger RNA are made up of a series of bases. In RNA, these bases are often labeled with the letters A, U, C, and G. A set of three bases makes up a codon.