Question

Which of the following statements about translation is true?

		There are 64 different aminoacyl-tRNA synthetases per cell, one for each codon.
		Peptidyl-transferase activity during translation is the property of a ribozyme.
		The codon for methionine appears only at the beginning of the mRNA for a protein, not anywhere in the middle.
		Prokaryotic and eukaryotic ribosomes are structurally and chemically identical.
		Ribosomes move along an mRNA in the 3’ to 5' direction.

Answer 1

First statement is false.

There are only 20 different amino acyl tRNA synthetase. (Because only 20 aminoacyl tRNA are there)

Second statement is true.

Pepetidyl transferase is an enzyme that catalyses the addition of aminoacid residue in order to grow polypeptide chain in photosynthesis. And it is mediated by ribosomal RNA, ribozyme.

Third statement cannot be true.

Prokaryotes uses an modified form of methionine (formyl methionine) for first aminoacid. When AUG is appeared in the middle of mRNA, methionine(not formyl methionine) is put into protien.

Fourth statement also wrong.

The eukaryotes have 60s and 40s subunit, and the prokaryotes have 50s and 30s.

Fifth statement is also false.

The ribosome move from 5 prime to 3 prime direction over mRNA during translation.