Process of translation

Question 1

What are the two important recognition steps for accurate translation

Answer 1

• the correct amino acid must be chosen for covalent attachment to a tRNA
• the selection of the amino-acid charged tRNA specified by mRNA

Question 2

Describe aminoacyl-tRNA synthetase

Answer 2

An enzyme that attaches an amino acid to the 3’-terminal ribose residue of its corresponding tRNA to form aminoacyl-tRNA.

Question 3

It is important for the tRNA to be charged with the correct amino acid. How does this occur?

Answer 3

This occurs through codon-anticodon interactions. The aminoacyl group does not participate in this process. Many tRNAs bind 2-3 codons, therefore it seems that non-Watson-Crick base pairing occurs at the third codon-anticodon position.

Question 4

Explain the Wobble Hypothesis

Answer 4

It assumes that the first two codon-anticodon pairings have normal Watson-Crick geometry. The structural constraints that this places on the third codon-anticodon pairing ensures that its confromation does not differ drastically from that of a Watson-Crick pair. It was proposed that there could be a small amount of play or “wobble” in the third codon which allows limited conformational adjustments in its pairing geometry. So it allows for non-Watson-Crick pairing.

Question 5

Describe the components of E.colis ribosome

Answer 5

The name ribosome is derived from the fact that it is made of 2/3 RNA and 1/3 protein. The E.coli ribosome has a sedimentation coefficient of 70S. The small subunit (30S) consists of a 16S rRNA molecule and 21 different polypeptides. The large subunit (50S) consists of a 5S rRNA molecule, a 23S rRNA molecule and 31 different polypeptides.