Question

The genetic code contains 61 codons to specify the 20 common amino acids. Many organisms carry fewer than 61 different tRNA genes in their genomes. These genomes take advantage of isoaccepting tRNAs and the rules governing third-base wobble to encode fewer than 61 tRNA genes. Use these rules to calculate the minimal number of tRNA genes required to specify all 20 of the common amino acids.

Accepted Answer

Understand the concept of codons and tRNAs: Codons are sequences of three nucleotides that specify amino acids. There are 61 codons for amino acids, but due to the degeneracy of the genetic code, multiple codons can specify the same amino acid. tRNAs are molecules that match codons with their corresponding amino acids during translation. Learn about isoaccepting tRNAs: Isoaccepting tRNAs are different tRNA molecules that carry the same amino acid but recognize different codons. This reduces the number of distinct tRNA genes required in the genome. Understand the wobble hypothesis: The wobble hypothesis explains that the third base of a codon can form non-standard base pairs with the first base of the anticodon in tRNA. This allows one tRNA to recognize multiple codons, further reducing the number of tRNA genes needed. Determine the minimal number of tRNA genes: To calculate the minimal number of tRNA genes, consider the number of codons for each amino acid and how many of these can be recognized by a single tRNA due to wobble pairing. For example, codons ending in U or C can often be recognized by the same tRNA, and codons ending in A or G can be recognized by another tRNA. Sum the minimal number of tRNAs required for all amino acids: For each of the 20 amino acids, calculate the minimum number of tRNAs needed based on the wobble rules and isoaccepting tRNAs. Add these numbers together to find the total minimal number of tRNA genes required to specify all 20 amino acids.

비슷한 문제에 대한 검증된 영상 답변:

주요 개념

Codons and Amino Acids

tRNA and Isoaccepting tRNAs

Wobble Hypothesis