Question

In Hb S, a ___ residue is replaced by a ___ residue.

a) Aspartate; lysine
b) Glutamate; histidine
c) Glycine; valine
d) Glycine; isoleucine

Answer 1

In sickle cell hemoglobin (Hb S), a glutamate residue is replaced by a valine residue, leading to sickle cell anemia due to a mutation in the DNA.

Step-by-step explanation:

In Hb S, commonly known as sickle cell hemoglobin, a glutamate residue is replaced by a valine residue. This single amino acid substitution occurs at the seventh position in the beta chain of hemoglobin, which significantly alters the protein's structure and function, leading to sickle cell anemia. The mutation is due to a single base change in the DNA, a point mutation, which changes the amino acid that is added during protein synthesis.