living organisms require energy to function and this includes each and every one of the trillions of cells that constitute the human body. Define in detail and use diagrams appropriate to show how cells extract, use and store energy including but to limited to discussion of cell respiration, glucose, pyruvic acid, glycolysis, krebs cycle, atp, nadh and fadh and electron transport. how much by the complete breakdown of glucose? why is breathing necessary for cellular respiration in animals?
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To understand how cells extract, use, and store energy, we can look at the process of cellular respiration which occurs in the mitochondria of cells. Cellular respiration is the process by which cells convert glucose into ATP (adenosine triphosphate), the main energy currency of living organisms.
Here is a breakdown of the steps involved in cellular respiration:
1. Glycolysis: The process starts with the breakdown of glucose, a six-carbon sugar, into two molecules of pyruvic acid, a three-carbon compound. Glycolysis occurs in the cytoplasm and does not require oxygen. It produces a small amount of ATP.
Diagram:
Glucose (6-carbon) -> 2 Pyruvic acid (3-carbon) + ATP
2. Pyruvate Oxidation: In the presence of oxygen, each pyruvic acid molecule moves into the mitochondria. Inside the mitochondria, each pyruvic acid is converted into Acetyl CoA. Carbon dioxide is also produced during this step.
Diagram:
Pyruvic acid (3-carbon) + Oxygen -> Acetyl CoA + Carbon Dioxide
3. Krebs Cycle (Citric Acid Cycle): Acetyl CoA enters the Krebs cycle, a series of chemical reactions that occur in the mitochondria. During this cycle, Acetyl CoA is broken down, releasing carbon dioxide and producing ATP, NADH, and FADH₂. NADH and FADH₂ are energy-rich molecules that carry high-energy electrons to the next step.
Diagram:
Acetyl CoA -> Carbon Dioxide + ATP + NADH + FADH₂
4. Electron Transport Chain (ETC): The high-energy electrons carried by NADH and FADH₂ move through a series of proteins in the inner mitochondrial membrane. As the electrons flow, energy is released and used to pump protons (H⁺) across the membrane, creating an electrochemical gradient. This gradient drives the synthesis of ATP through a process called chemiosmosis.
Diagram:
NADH + FADH₂ + Oxygen + H⁺ -> ATP + Water
Overall, the complete breakdown of glucose through cellular respiration produces a total of 36-38 ATP molecules. This number varies slightly depending on the efficiency of the electron transport chain.
Breathing, specifically the exchange of oxygen and carbon dioxide in the lungs, is necessary for cellular respiration in animals because oxygen is the final electron acceptor in the electron transport chain. Without oxygen, the electron transport chain cannot function properly, leading to a decreased energy production in cells. Breathing ensures a continuous supply of oxygen to the cells and removes carbon dioxide, a waste product of cellular respiration.