Question

38. T or F. Every protein, as it emerges from the ribosome, begins with methionine.

39. T or F. Enzymes speed up reactions by lowering the free energy of the products of a
particular reaction. This makes the reaction more energetically favorable and thus more
likely to occur.

40. T or F. At the termination of translation, a release factor binds to the ribosome at the A
site and causes the ribosome to add a water molecule, instead of another amino acid, to
the amino acid in the P site.

41. T or F. A parallel plate flow chamber can be used to expose a surface to a known
magnitude of shear stress. This can help investigate the response of cells to shear
stress and to clarify the intracellular signaling pathways that are activated by shear
stress.

Answer 1

38. AUG is the start codon which codes for methionine in eukaryotes and formylmethionine in prokaryotes. But this event only takes place at the start codon. There might be possibilities where the start codon can get altered and code for amino acid other than methionine. Moreover for mitochondria and stress related proteins like Heat Shock proteins, AUG is not the start codon.

Owing to post translational mechanisms and modifications which the proteins undergoes, often methionine is removed from the N terminal end of a polypeptide. So, in that case, the protein is unable to begin with methionine.

So, the above statement is false.