How does superoxide dismutase help bacteria to deal with free radicals? How does catalase help a bacteria to deal with hydrogen peroxide?
The correct answer and explanation is:
Sure! Here’s the detailed explanation:
Answer:
- Superoxide dismutase (SOD) helps bacteria by catalyzing the conversion of the superoxide radical (O₂⁻), a harmful reactive oxygen species (ROS), into oxygen (O₂) and hydrogen peroxide (H₂O₂).
- Catalase then helps bacteria by converting hydrogen peroxide (H₂O₂), which is also toxic, into harmless water (H₂O) and oxygen (O₂).
Explanation:
Bacteria, like many aerobic organisms, are constantly exposed to reactive oxygen species (ROS), which are highly reactive molecules that can cause serious damage to cellular components such as DNA, proteins, and lipids. Two common ROS are superoxide radicals (O₂⁻) and hydrogen peroxide (H₂O₂).
1. Role of Superoxide Dismutase (SOD):
Superoxide radicals are generated as byproducts of normal cellular respiration and from environmental stresses. These radicals are dangerous because they can initiate chain reactions that damage the cell.
Superoxide dismutase is an enzyme that protects bacteria by catalyzing the dismutation reaction:
2 O₂⁻ + 2 H⁺ → O₂ + H₂O₂
In this reaction, SOD converts two molecules of superoxide into molecular oxygen and hydrogen peroxide. This step reduces the concentration of superoxide radicals, but it produces hydrogen peroxide, which is still harmful.
2. Role of Catalase:
Hydrogen peroxide, although less reactive than superoxide, can still damage cellular components and can generate even more reactive hydroxyl radicals (•OH) via Fenton reactions. To prevent this, bacteria produce the enzyme catalase, which catalyzes the breakdown of hydrogen peroxide into water and oxygen:
2 H₂O₂ → 2 H₂O + O₂
This reaction quickly removes hydrogen peroxide, detoxifying the cell environment and preventing oxidative damage.
Summary:
- Superoxide dismutase converts superoxide radicals into hydrogen peroxide and oxygen, neutralizing the superoxide radicals’ damaging effects.
- Catalase then converts the hydrogen peroxide into water and oxygen, preventing the buildup of hydrogen peroxide and further oxidative stress.
Together, these enzymes form a critical defense system that allows bacteria to survive and thrive in oxygen-rich environments by protecting them from the toxic effects of free radicals and reactive oxygen species.