question_answer

The pair in which both species have iron is

A)  nitrogenase, cytochromes

B)  carboxypeptidase, haemoglobin

C)  haemocyanin, nitrogenase

D)  haemoglobin, cytochromes

Correct Answer: D

Solution :

 Cytochromes are conjugated proteins consisting of an apoprotein and a prosthetic group (haeme). The haeme consists of a porphyrin with a central iron atom. The name haemoglobin is the concentration of haeme and globin, reflecting the fact that each subunit of haemoglobin is a globular protein with an embedded heme (or haem) group, each heme group contains an iron atom, and this is responsible for the binding of oxygen. The most common types of haemoglobin contains four such subunits, each with one heme group.