THE MOLECULAR BASIS OF INHERITANCE
DNA MAKES RNA MAKES PROTEIN
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
Several different codons can specify the same amino acid.
|
|
|
Each codon specifies a different amino acid.
|
|
|
Some amino acids have no link to a codon.
|
|
|
Each amino acid is specified by only one codon.
|
Detailed explanation-1: -Genetic code show degeneracy which means that multiple codons specify particular amino acid; asparagine is encoded by “GAU and GAC". Degeneracy allows one amino acid to be encoded by multiple codons; thus 61 codons for 20 amino acids. The correct option is B.
Detailed explanation-2: -Of these 64 codons, 61 represent amino acids, and the remaining three represent stop signals, which trigger the end of protein synthesis. Because there are only 20 different amino acids but 64 possible codons, most amino acids are indicated by more than one codon.
Detailed explanation-3: -Thus, the smallest combination of four bases that could encode all 20 amino acids would be a triplet code. However, a triplet code produces 64 (43 = 64) possible combinations, or codons. Thus, a triplet code introduces the problem of there being more than three times the number of codons than amino acids.
Detailed explanation-4: -The genetic code has 64 codon and each specifies only one amino acids but there are some codons such as GAA and GAG both specify one amino acid i.e., glutamic acid and are called as redundancy or degeneracy.
Detailed explanation-5: -Amino acids differ from each other with respect to their side chains, which are referred to as R groups. The R group for each of the amino acids will differ in structure, electrical charge, and polarity.