Question

Which five statements about hemoglobin and myoglobin structure are true? Both hemoglobin and myoglobin contain a prosthetic group called heme, which contains a central iron atom. Each iron atom can form six coordination bonds. One of these bonds is formed between iron and oxygen. Heme is composed of an organic protoporphyrin component and a metal atom. By itself, heme is not a good oxygen carrier. It must be part of a larger protein to prevent oxidation of the iron atom. Each hemoglobin molecule can bind four oxygen molecules; each myoglobin can bind only one oxygen molecule Hemoglobin and myoglobin are heterotetramers. Molecular oxygen binds irreversibly to Fe2+ in heme.

Answer 1

Haemoglobin is a tetramer composed of 2 alpha and 2 beta subunits while myoglobin is composed of single polypeptide chain. Both have a heme prosthetic group composed of protoporphyrin ring and a central iron atom. The binding of oxygen to iron is reversible because of that only haemoglobin is able to bind to oxygen in lungs and deliver this oxygen to the tissue. Fe forms 6 co-ordinate bond 4 with nitrogen of pyrrole ring 1 with oxygen and 1 with histidine of globin.

So only last 2 option are incorrect while the first 5 options are correct