Question

Which of the following statements about cytochrome c is true?

A) Cytochrome c shuttles electrons between the NADH dehydrogenase complex and cytochrome c reductase complex.
B) When cytochrome c becomes reduced, two cysteines (sulfur-containing amino acids) become covalently bound to a heme group.
C) Cytochrome c shuttles electrons between the cytochrome c reductase complex and the cytochrome c oxidase complex
D) Cytochrome c is the last protein in the electron-transport chain, passing its electrons directly to molecular oxygen, a process that reduces O2 to H20.

Answer 1

Cytochrome c shuttles electrons between the cytochrome c reductase complex (Complex III) and the cytochrome c oxidase complex (Complex IV), confirming option C as the correct statement.

Step-by-step explanation:

The true statement about cytochrome c (Cyt c) is that C) Cytochrome c shuttles electrons between the cytochrome c reductase complex and the cytochrome c oxidase complex. Cytochrome c is an electron carrier that moves along the inner membrane's surface facing the intermembrane space and shuttles electrons from Complex III, also known as cytochrome c reductase or cytochrome bc1 complex, to Complex IV, which is also referred to as cytochrome c oxidase.

Complex III receives electrons from coenzyme-Q, and then passes them to cytochrome c which can only accept one electron at a time, unlike Q which can carry pairs of electrons. Finally, cytochrome c transfers the electrons to Complex IV where the electrons contribute to the reduction of oxygen into water.