Answer:
A point mutation can be described as a mutation in which changes occur in a single nucleotide. A nucleotide may get changed, deleted or inserted from the sequence of DNA. Point mutations can be harmless or harmful depending on the nucleotide in which the changes occur.
A change in just one nucleotide can result in the formation of wrong amino acid and hence changed or wrong proteins can be formed. If the original protein was involved in cellular reproduction, then the entire process of reproduction can be affected by a point mutation.
Sickle- cell anaemia is a disease in which the body fails to produce enough healthy red blood cells. This disease occurs due to point mutation. Point mutation occurs where glutamine (GAG) of the β-globin gets changed into valine (GUG). This change causes the haemoglobin to get a deformed structure due to which it is not able to carry out oxygen.
Answer:
D. GTP
Explanation:
Initiation of protein synthesis includes binding of mRNA to small ribosome subunit and initiation aminoacyl tRNA. The pairing of the anticodon of the initiating aminoacyl tRNA and initiation codon of mRNA requires GTP hydrolysis and marks the beginning of protein synthesis.
Elongation stage of protein synthesis requires movement of the ribosome along the mRNA which in turn is facilitated by GTP hydrolysis. As the ribosome moves along the mRNA, the codon of mRNA bind to the respective anticodon of aminoacyl tRNA by using the energy of GTP hydrolysis. The GTPase activity of elongation factor Ef-Tu ensures the fidelity of the process.
The release factors that recognize the stop codon and serve to mark the termination of protein synthesis use the energy of GTP hydrolysis during the process.
