Question

A certain bacterial mRNA is known to represent only one gene and to contain about 800 nucleotides. If you assume that the average amino acid residue contributes 110 to the peptide molecular weight, the largest polypeptide that this mRNA could code for would have a molecular weight of about _______.

Answer 1

A certain bacterial mRNA is known to represent only one gene and to contain about 800 nucleotides. If you assume that the average amino acid residue contributes 110 to the peptide molecular weight, the largest polypeptide that this mRNA could code for would have a molecular weight of about _______.

A) 800.

B) 5,000.

C) 30,000.

D) 80,000.

E) An upper limit cannot be determined from the data given

Answer:

c.  30,000

Explanation:

The gene has a total of 800 nucleotides and would be transcribed into an mRNA having about 800 nucleotides. The nucleotides of mRNA are read in the form of genetic triplets. This means that the mRNA with 800 nucleotides would have about 800/3= 266.66 or 266 genetic codes. This mRNA would be translated into a polypeptide chain having around 266 amino acids.

One amino acid contributes 110 to the molecular weight. The total molecular weight of the largest possible polypeptide that can be encoded by the said gene would b 266 x 110= 29260 (around 30,000).