THE MOLECULAR BASIS OF INHERITANCE
DNA MAKES RNA MAKES PROTEIN
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[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Detailed explanation-1: -A stop codon is a sequence of three nucleotides (a trinucleotide) in DNA or messenger RNA (mRNA) that signals a halt to protein synthesis in the cell. There are 64 different trinucleotide codons: 61 specify amino acids and 3 are stop codons (i.e., UAA, UAG and UGA).
Detailed explanation-2: -Prokaryotes use alternate start codons significantly, mainly GUG and UUG. E. coli uses 83% AUG (3542/4284), 14% (612) GUG, 3% (103) UUG and one or two others (e.g., an AUU and possibly a CUG). Well-known coding regions that do not have AUG initiation codons are those of lacI (GUG) and lacA (UUG) in the E.
Detailed explanation-3: -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-4: -The simplest answer is that redundancy has evolved into these codons. A cell would not want a mutation at the stop location and have the protein get excessively large before another stop codon is hit.