Internal respiration refers to the process of using oxygen by organisms to produce energy within cells. Here is a step by step explanation of internal respiration:
Definition of internal respiration:
Internal respiration is a process that occurs inside the cells of organisms, where oxygen is taken from the environment and used to produce energy in the form of ATP (adenosine triphosphate). This process involves complex chemical reactions in the cell’s mitochondria.
Internal respiration is the breathing process that occurs inside cells to produce the energy needed by the cells. The process of internal respiration involves the breakdown of glucose in mitochondria to produce ATP (adenosine triphosphate), which is the main energy source for cells.
Internal respiration consists of three main stages, namely glycolysis, the citric acid cycle (Krebs cycle), and the electron transport chain. This stage occurs sequentially and involves a number of enzyme molecules that play a role in breaking down glucose.
In the glycolysis stage, glucose is broken down into two pyruvate molecules in the cell cytoplasm. During this process, several molecules of ATP and NADH (reduced nicotinamide adenine dinucleotide) are produced.
Next, pyruvate enters the mitochondria and undergoes oxidative decarboxylation, producing acetyl-CoA which enters the citric acid cycle. In this cycle, acetyl-CoA undergoes a series of chemical reactions that produce ATP, NADH, and FADH2 (reduced flavin adenine dinucleotide).
NADH and FADH2 produced in the citric acid cycle then enter the electron transport chain in the mitochondrial membrane. The electron transport chain uses the energy contained in NADH and FADH2 molecules to produce ATP through oxidative phosphorylation.
Overall, internal respiration allows cells to produce large amounts of ATP that is used to power various cellular processes. This process is important for the survival of organisms because the energy produced from internal respiration is used to carry out daily activities efficiently.
Stages of internal respiration:
Internal respiration consists of three main stages, namely glycolysis, Krebs cycle, and oxidative phosphorylation.
- Glycolysis: This stage occurs in the cytoplasm of the cell. The glucose molecule is broken down into two pyruvate molecules, producing a small amount of ATP and molecules that have the potential to produce more ATP at a later stage.
- Krebs Cycle: This stage occurs in the mitochondria. Pyruvate molecules from glycolysis are converted into acetate compounds and then enter the Krebs cycle. In this process, acetate compounds are oxidized to CO2 and energy in the form of ATP, NADH, and FADH2.
- Oxidative phosphorylation: This stage also occurs in mitochondria. The energy-containing molecules (NADH and FADH2) produced during the previous stage release electrons that flow through the electron transport chain. This process produces ATP through ATP synthesis by the ATP synthase enzyme.
Importance of internal respiration:
Internal respiration is an important process for organisms to produce the energy needed to carry out cellular activities, such as muscle contraction, protein synthesis, and transport of substances across cell membranes. Without internal respiration, organisms would not be able to survive.
Internal respiration is a process within an organism’s cells that uses oxygen to produce energy in the form of ATP. The stages include glycolysis, the Krebs cycle, and oxidative phosphorylation. This process is important to meet cellular energy needs and is vital for the survival of the organism.