Cell respiration is a series of oxidative reactions by which cells gradually release energy from glucose and transfer it to molecules of ATP (adenosine triphosphate).
Energy stored in ATP is immediately available for cellular activities such as contracting muscles, passing an impulse along a nerve, or pumping ions by active transport.
The equation for the complete aerobic respiration of one molecule of glucose:
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
Glucose combines with oxygen to produce energy (ATP) plus the waste products (carbon dioxide and water).
ATP- adenosine triphosphate
ATP is the special high-energy molecule that stores energy for immediate use in ...view middle of the document...
Anaerobic respiration originated billions of years ago when there was no free oxygen in Earth’s atmosphere. Today it is the sole means by which anaerobic bacteria such as Clostridium botulinum (the bacteria that causes a form of food poisoning, botulism) release energy from food.
Alcohol fermentation is the process by which certain cells convert pyruvic acid or pyruvate from glycolysis into ethyl alcohol and carbon dioxide in the absence of oxygen. The bread-baking industry depends on the ability of yeast to carry out fermentation and produce the carbon dioxide that causes bread to rise. Also, the beer, wine, and liquor industries depend on yeast to ferment sugar into ethyl alcohol.
Lactid Acid fermentation-
Lactid acid fermentation occurs during strenuous exercise when the body cannot keep up with the increased demand for oxygen by skeletal muscles. Pyruvic acid produced by glycolysis converts to lactic acid and builds up in muscles, causing fatigue and burning. The expression, “No pain, no gain” refers to the pain caused by lactic acid buildup in skeletal muscles. When an increase in blood flow restores proper oxygen levels, the muscle tissue reverts to the more efficient aerobic respiration and lactic acid is removed from the muscles. Lactic acid is carried to the liver, where it is converted back to pyruvic acid.
Aerobic respiration- (when oxygen is present)
Aerobic respiration consists of three processes: glycolysis, the Krebs cycle, and the electron transport chain.
Glycolysis is the anaerobic phase of aerobic respiration. One molecule of glucose breaks apart into two molecules of pyruvate. Pyruvate or pyruvic acid, is essentially one-half of a glucose molecule and is the raw material for the next step in respiration (the Krebs cycle).
Glycolysis occurs in the cytoplasm.
Glycolysis is a complex, multi-step process, each step of which is controlled by a different enzyme.
Two molecules of ATP supply the energy of activation (the energy needed to begin the reaction).
Glycolysis releases 4 ATP molecules, resulting in a net gain of 2 ATP.
1 Glucose + 2 ATP → 2 pyruvate + 4 ATP + 2 NADH (net gain 2 ATP).
Glycolysis produces pyruvic acid and a small amount of ATP.
The Krebs Cycle- (citric acid cycle)
The Krebs cycle, also known as the citric acid cycle, is the first stage of the aerobic phase of cellular respiration.
Pyruvic acid (from glycolysis) combines with coenzyme A (a vitamin A derivative) to form Acetyl-CoA, which enters the Krebs cycle.
Pyruvic acid + coenzyme A → Acetyl-CoA.
This (Krebs cycle) occurs in the matrix of the mitochondria.
Each turn of the Krebs cycle produces 1 molecule of both ATP and FADH2 plus 3 molecules of NADH.
The by-product is CO2, which is exhaled.
The Krebs cycle produces a small amount of ATP, carbon dioxide and NADH and FADH2.
NADH and FADH2-
NADH and FADH2 molecules are an important part of cell respiration.
NADH and FADH2 are...