RESPIRATION IN ORGANISM
Respiration in organisms is the process by which they convert chemical energy stored in food molecules (mainly glucose) into usable energy in the form of adenosine triphosphate (ATP). This energy is used for various life processes like growth, repair, and maintenance. There are two main types of respiration: aerobic and anaerobic.
1. Aerobic Respiration
- Definition: Aerobic respiration occurs in the presence of oxygen and is the most efficient way of producing energy.
- Formula: Glucose+Oxygen→Carbon dioxide+Water+Energy (ATP)\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon dioxide} + \text{Water} + \text{Energy (ATP)}Glucose+Oxygen→Carbon dioxide+Water+Energy (ATP)
- It takes place in the mitochondria of the cells.
- The process involves the breakdown of glucose molecules through several stages:
- Glycolysis: The breakdown of glucose into pyruvate (occurs in the cytoplasm).
- Krebs Cycle (Citric Acid Cycle): Pyruvate is further broken down in the mitochondria to release energy.
- Electron Transport Chain: A series of reactions that transfer electrons to produce a large amount of ATP.
- Aerobic respiration produces a lot of energy and is typical in most multicellular organisms (humans, animals, and plants).
2. Anaerobic Respiration
- Definition: Anaerobic respiration occurs in the absence of oxygen and produces energy less efficiently than aerobic respiration.
- Formula (in animals): Glucose→Lactic acid+Energy (ATP)\text{Glucose} \rightarrow \text{Lactic acid} + \text{Energy (ATP)}Glucose→Lactic acid+Energy (ATP)
- In plants and yeast, anaerobic respiration produces ethanol and carbon dioxide.
- This type of respiration is used when oxygen is in short supply, like in muscles during intense exercise.
- Anaerobic respiration is less efficient because it produces less ATP compared to aerobic respiration.
Differences Between Aerobic and Anaerobic Respiration:
| Feature | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen Required | Yes | No |
| Energy Produced | High (38 ATP per molecule of glucose) | Low (2 ATP per molecule of glucose) |
| By-products | Carbon dioxide and water | Lactic acid (in animals) or ethanol (in plants and yeast) |
| Location | Mitochondria | Cytoplasm |
| Organisms | Most animals, plants, and many microorganisms | Some bacteria, yeast, and muscle cells under stress |
Importance of Respiration:
- Energy production: Respiration provides the energy required for growth, reproduction, and maintenance of the organism’s functions.
- Cell functions: ATP produced during respiration powers many cellular processes, including protein synthesis, DNA replication, and ion transport across membranes.
Respiration in Different Organisms:
- Humans and Animals: Use mainly aerobic respiration, but switch to anaerobic respiration during intense activity when oxygen demand exceeds supply (e.g., during heavy exercise).
- Plants: Under normal conditions, plants use aerobic respiration. However, in conditions where oxygen is limited (e.g., in waterlogged soil), they can switch to anaerobic respiration.
- Yeast and Microorganisms: Yeasts can carry out alcoholic fermentation (a form of anaerobic respiration) when oxygen is absent, producing ethanol and carbon dioxide.