Question

Explain the following: Degenerate code, Unambiguous code, Universal code, Initiator code.

Answer 1

Degenerate code: A code in which several codewords have the same meaning. The genetic code is degenerate because there are many instances in which different codons specify the same amino acid. A genetic code in which some amino acids may each be encoded by more than one codon.
Unambiguous: Each codon specifies a particular amino acid and only that amino acid. One amino acid can be coded by several different codons. But one codon can code just for one amino acid, not more. Hence, the unambiguity of the genetic code.
Universal code: The genetic code is pretty similar in most of the organisms. It means that codon, which codes methionine in human, does the same in prokaryotes. This point is not exactly true as recently, scientists have discovered many exceptions from this rule. The genetic code is not universal, but it is still predominant.
Initiator codon or start codon: A specific set of 3 bases, "AUG", known as the "start codon", signifies the gene to start transcribing. There are 64 possible codons (four possible nucleotides at each of three positions, hence, 43 possible codons) and only 20 standard amino acids; hence the code is redundant and multiple codons can specify the same amino acid.