Biosynthesis of Major Reactive Oxidative Species

The video discusses the biosynthetic pathway of reactive oxidative species (ROS), highlighting their formation, roles, and impact on cells. It explains how ROS, primarily originating from molecular oxygen, can lead to free radicals that damage proteins, lipids, and DNA, potentially causing cancer. The video also covers the protective role of enzymes like catalase and the destructive mechanisms involving myeloperoxidase and the Fenton reaction in immune cells. Additionally, it explores reactive nitrogen species and their regulatory functions in protein activity.

What is the primary consequence of reactive oxidative species (ROS) in cells?

• They enhance cellular respiration.

• They stabilize DNA structure.

• They form free radicals that can damage cellular components.

• They increase protein synthesis.

Which molecule is the origin of most free radicals, excluding nitric oxide?

• Carbon dioxide

• Nitrogen

• Molecular oxygen (O2)

• Hydrogen

What enzyme converts superoxide into hydrogen peroxide?

• NADPH oxidase

• Catalase

• Myeloperoxidase

• Superoxide dismutase

What is the role of catalase in cells?

• It generates superoxide.

• It detoxifies hydrogen peroxide into water and oxygen.

• It forms hydroxyl radicals.

• It converts arginine into nitric oxide.

Which enzyme is responsible for converting hydrogen peroxide into hypochlorous acid?

• Catalase

• Superoxide dismutase

• NADPH oxidase

• Myeloperoxidase

What is the most dangerous type of free radical mentioned in the video?

• Hydroxyl radical

• Superoxide

• Nitric oxide

• Peroxynitrite

What is the purpose of the Fenton reaction in immune cells?

• To stabilize DNA

• To detoxify hydrogen peroxide

• To generate hydroxyl radicals for pathogen destruction

• To produce nitric oxide

What amino acid is the starting point for the formation of reactive nitrogen species?

• Serine

• Glutamine

• Arginine

• Lysine

What is the role of peroxynitrite in cells?

• It damages DNA.

• It detoxifies superoxide.

• It regulates protein activity through nitrosylation.

• It forms hydroxyl radicals.

Approximately what percentage of the proteome is regulated by nitrosylation?

• 50%

• 30%

• 70%

• 10%