Question

5. Which of the following is a correct description of the origin of the reactive oxygen species known as the superoxide radical (O2 ∙- )?

A) It is a product of superoxide dismutase.

B) It is a naturally occurring byproduct of metabolism.

C) It comes exclusively from exogenous (outside the body) sources.

D) It is a specific form of electron carrier serving as a cofactor for certain enzymes.

E) It resulted from malfunction of the electron transport chain and oxidative phosphorylation

Answer 1

5. Which of the following is a correct description of the origin of the reactive oxygen species known as the superoxide radical (O2 ∙- )?

E) It resulted from malfunction of the electron transport chain and oxidative phosphorylation.

Though option (B) ' naturally occurring byproduct of metabolism.' is also aprtially correct but option (E) fits perfectly for the description. Oxygen containing chemically reactive molecules are called as reactive oxygen species. It includes peroxides, superoxide, singlet oxygen, hydroxyl radical and alpha-oxygen. ROS are naturally produced as a product of cellular metabolism. When electrons leak from the series of carries of ETC, they get transgormed to mitochondrial superoxide before they get reduced to water at Complex IV,. These superoxides serves as a substrate for superoxide dismutase results in production of highly reactive hydrogen peroxide.