F.Sc part 1: Biology-Chapter 4: Mitochondria (simple concept) by The Pool of Science

 Structure of Mitochondria:

Mitochondria have a double membrane structure. The outer membrane is smooth, while the inner membrane is highly folded, forming structures called cristae. These folds increase the surface area inside the mitochondria, allowing for more space for chemical reactions to take place.

Function of Mitochondria: The main function of mitochondria is to generate energy in the form of a molecule called adenosine triphosphate (ATP) through a process known as cellular respiration. This energy is essential for various cellular activities, including growth, movement, and maintaining homeostasis.

Cellular Respiration: Cellular respiration is a complex series of chemical reactions that occur in the mitochondria. It involves the breakdown of glucose (sugar) and other organic molecules to release energy. The process consists of three main stages: glycolysis, the citric acid cycle (Krebs cycle), and the electron transport chain.

1. Glycolysis: This occurs in the cytoplasm of the cell and involves the breakdown of glucose into smaller molecules. It generates a small amount of ATP and molecules that enter the next stages of respiration.

2. Citric Acid Cycle: This takes place in the mitochondrial matrix, the inner part of the mitochondria. During this cycle, molecules produced from glycolysis are further broken down, releasing carbon dioxide and high-energy electrons. These electrons are carried by molecules like NADH and FADH2.

3. Electron Transport Chain: The inner mitochondrial membrane contains proteins and complexes that make up the electron transport chain. High-energy electrons from NADH and FADH2 move through this chain, releasing energy. This energy is used to pump protons (H+ ions) across the inner membrane, creating an electrochemical gradient.

The movement of protons back into the mitochondrial matrix through a protein called ATP synthase generates ATP molecules. This process is called chemiosmotic coupling and is how ATP, the cell's energy currency, is produced.

In summary, mitochondria are vital organelles responsible for producing energy in the form of ATP through cellular respiration. This energy is essential for powering various cellular processes, allowing the cell to function properly.