Question

Why does catalase favor natural selection?

Answer 1

The enzyme catalase provides a beneficial characteristic to those who are living in an oxygen rich environment (aerobes). Oxygen metabolism produces toxic byproducts which includes hydrogen peroxide, superoxide radicals, singlet Oxygen, etc. (Reactive Oxygen Species). ROS generation in a large amount causes lipid peroxidation, DNA damage, enzyme and protein degradation, etc. Aerobic organisms, due to the presence of enzymes such as catalase, are protected against these cellular damages. Catalase is responsible for breaking down hydrogen peroxide into oxygen and water, thus, protecting the cells from oxidative damage. The enzyme is absent in anaerobic organisms, as a result of which, these organisms can not survive in presence of oxygen.

Thus, presence of catalase favors natural selection of aerobes by increasing their ability to survive and reproduce in an oxygen rich environment.