Life Processes

RESPIRATION – A LIFE PROCESS

• All living organisms eat food to produce energy for the normal functioning of the body.
• The biochemical process of respiration involves taking in oxygen (of air) into the cells to get the energy to perform certain life processes essential for survival.
• Oxygen is used for releasing energy by burning food, and then eliminating the waste products (carbon dioxide and water) from the body.
• Glucose from the food that organisms consume, gets broken down into simpler substances and energy is released.
• Since the process of respiration which release energy takes place inside the cells of the body, it is known as cellular respiration.
• Respiration is just opposite of photosynthesis.
• Respiration involves the exchange of gases and burning of food.
• It is a redox reaction which can take place with or without oxygen and takes place in mitochondria of the cell and releases energy in the form of ATP.

Characteristics:

• Glucose is C₆H₁₂O₆. It is a six carbon atom compound. It is the simple food which gets oxidised in the cells of organisms during respiration.
• The oxidation of glucose to pyruvic acid (or pyruvate) it called glycolysis.
• Pyruvic acid is a three carbon atom compound. It is also called pyruvate. The formula of pyruvic acid or pyruvate is
• ATP (Adenosine triphosphate) is known as the energy currency for most of the cellular processes. It is formed from ADP (Adenosine diphosphate) and inorganic phosphate.

Types of respiration:

• Organisms obtain energy in different ways, like humans need air to live.
• Oxygen from the air is used to release energy because of which it is called aerobic respiration.
• However, some species of bacteria and algae or some prokaryotes do not need oxygen to generate energy and the process by which they obtain energy is called anaerobic respiration.
• There are two types of respiration:
• Aerobic Respiration
• Anaerobic Respiration

Aerobic Respiration:

• The respiration which uses oxygen is called aerobic respiration.
• Energy is released by the breakdown of glucose into carbon dioxide and water in the mitochondria.
• Glucose is converted into pyruvate in the first step, similar to anaerobic respiration.
• However, the amount of energy released is much greater than during anaerobic respiration.

• If oxygen is present in the cells, then pyruvate is completely oxidised to carbon dioxide and water, and produces a lot of energy is produced which is immediately used to synthesize a molecule called ATP.
• It acts as the energy currency of cellular processes like the contraction of muscles, protein synthesis, conduction of nervous impulses, etc in the human body.

• Anaerobic Respiration:
  • The respiration which takes place without oxygen is called anaerobic respiration.
  • The first step is the conversion of glucose which is a 6 Carbon molecule into a simpler sugar called pyruvate, a 3 Carbon molecule in the cytoplasm.
  • In the absence of oxygen, pyruvate gets converted to other substances, and energy is released.
  • The process of anaerobic respiration in yeast can be depicted by the following equation.

• Bacteria and yeast respire anaerobically i.e., in the absence of oxygen.
• In this way, the process of fermentation takes place.
• In yeast, pyruvate gets broken down into ethanol, and carbon dioxide and energy are released.
• Anaerobic respiration takes place in our muscles during vigorous physical exercise when oxygen gets used up faster in the muscle cells than can be supplied by the blood.
• And lactic acid is produced which causes muscle cramps.