Question

Number of cytochrome complexes present in the electron transport chain in mitochondria is
A) 1
B) 2
C) 3
D) 4

Answer 1

Hint: Cytochrome complexes are multiprotein structures present in the inner mitochondrial membrane. Mitochondria is a double membrane organelle, which produces ATP which is called the energy currency of a cell.

Complete Answer:
- The electron transport chain consists of 4 large, multiprotein complexes which might be embedded in the inner membrane of mitochondria with two small diffusible electron carriers shuttling electrons between these complexes.
- The electron transport chain is found to be present in multiple copies on the inner mitochondrial membrane. In the electron transport chain, the electrons are transferred by the collection of co-enzymes and cytochromes.
- In the electron transport chain, there are cytochrome complexes, cytochrome bc1​ and cytochrome c oxidase. The first cytochrome complex has cytochrome b, FeS complex and cytochrome c1​. Cytochrome c1 transfers the electron to cytochrome c.
- The second cytochrome complex is made up of cytochrome a and cytochrome a3​.This complicated facilitates switching the electron to oxygen.
- Thus, cytochromes are present in the electron transport chain, which are required for electron transfer.

Thus the precise solution is option (D) 4.

Note: The efflux of protons from the mitochondrial matrix creates an electrochemical gradient (proton gradient). This gradient is utilized by the FoF1 ATP synthase complicated to make ATP through oxidative phosphorylation. ATP synthase is on occasion defined as Complex V of the electron delivery chain.