Question

What is the minimum number of aminoacyl-tRNA synthetase enzymes needed to attach amino acids to all the various tRNA molecules?

1) 20
2) 61
3) 64
4) As many enzymes as there are different tRNAs are necessary.

Answer 1

A total of 20 aminoacyl-tRNA synthetase enzymes are needed, as there is one for each of the 20 different amino acids.

Step-by-step explanation:

The minimum number of aminoacyl-tRNA synthetase enzymes needed to attach amino acids to all the various tRNA molecules is 20. This is because there is at least one type of aminoacyl-tRNA synthetase for each of the 20 amino acids. These enzymes catalyze the attachment of an amino acid to its corresponding tRNA in a process known as 'charging' the tRNA.

Despite there being more than one tRNA for some amino acids and multiple codons (61) that code for amino acids, the specificity of the aminoacyl-tRNA synthetase to its amino acid ensures that only 20 different enzymes are necessary.