RESPIRATION IN LIVING ORGANISMS
1. Definition of Respiration
Respiration is a biological process, exclusive to biological living organisms. Non-biological entities such as metals (like iron), stone, plastic, etc., lack the capability to undergo respiration.
The crux of respiration involves the breakdown of food materials to yield energy in the form of ATP (Adenosine Tri Phosphate). Such food materials encompass glucose, proteins, fats, and carbohydrates. During respiration, gases like oxygen, carbon dioxide, nitrogen, and hydrogen sulphides are exchanged.
The quintessential equation for respiration:
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ATP)
2. The Importance of Respiration
2.1 Why Do Living Things Undergo Respiration?
Respiration is indispensable for the sustenance of life. It provides:
- Growth for living organisms;
- Facilitation of cellular constituents’ manufacture such as pigments, cell walls, membranes, and plant chemicals (phytochemicals);
- Conversion of stored potential energy (i.e. foods) into kinetic energy (ATP);
- Carbon cycle equilibrium by assimilating O2 and releasing CO2.
2.2 Living Organisms & Respiration
While all species respire to maintain life, the processes in larger organisms like animals and humans are more conspicuous than in microscopic entities such as Amoeba, Bacteria, Fungi, and tiny insects. Other examples of respiring organisms include plants, algae, yeasts, and earthworms.
2.3 Diverse Types of Respiration
Respiration types can be bifurcated based on the availability of oxygen (O2). There is aerobic respiration, occurring in the presence of O2, and anaerobic respiration in its absence.
2.4 Contrasting Aerobic & Anaerobic Respiration
| Criteria | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen Presence | Occurs with O2 | Lacks O2 |
| Energy Production | Yields 36 ATP | Yields 2 ATP |
| Food Breakdown | Complete | Incomplete |
| Location | Mitochondrion & cytosol | Cytosol only |
| End Products | CO2 and water | Ethanol and water |
2.5 Respiration Mechanisms
Respiration unfolds in three unique phases:
- Glycolysis: Initial stage of cellular respiration happening in the cytosol, breaking food substrates down to glucose and finally, pyruvate, with the production of ATP and NADH. No CO2 is generated here. Depending on oxygen availability, it can proceed to Kreb’s cycle or fermentation.
- Kreb’s Cycle: Occurring in the mitochondria, it yields additional ATP, CO2, NADH, and FADH2. It, along with fermentation, constitutes the second stage of respiration.
- Electron Transport Chain (ETC): The finale of respiration, it’s where the majority of ATP is synthesized, approximately 32 ATP molecules.
Overall, the process of respiration in living beings is intricate yet fundamental for survival, as can be depicted in the provided flow chart.
3. Delving Deeper: Extended Discussion on Respiration
3.1 The Essence of ATP in Respiration
ATP, or Adenosine Tri Phosphate, is often referred to as the ‘energy currency’ of the cell. This molecule holds energy within its bonds which is released when needed by the cell for various functions. The production of ATP is, therefore, the primary objective of respiration.
3.2 The Role of Mitochondria
The mitochondria, often termed the powerhouse of the cell, play a pivotal role in aerobic respiration. It’s where the Kreb’s cycle occurs, and it’s also the site for the ETC, ensuring maximum energy extraction from food molecules.
3.3 The Significance of Anaerobic Respiration
While aerobic respiration is more efficient, anaerobic respiration is vital for organisms in oxygen-deficient environments. It’s also crucial for short, intense activities in humans where the oxygen supply to muscles is momentarily insufficient.
3.4 Fermentation in Detail
Fermentation, a type of anaerobic respiration, varies based on organisms. For instance, in human muscles, it produces lactic acid, causing temporary muscle fatigue. In yeast, it leads to the production of alcohol, crucial for making bread and beverages.
4. References & Additional Materials
For those eager to delve deeper into respiration, here are some references and supplementary reading materials:
- Biology Forums
- Khan Academy
- Books:
- Functional Approach Biology, Edition VI
- Biological Sciences, Edition
- Botany for Degree Student by A. C. Dutta