Cellular respiration

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Getting energy to make ATP

Getting energy to make ATPCellular RespirationThe process by which mitochondria break down food molecules to produce ATP is called cellular respiration. There are 3 stages of cellular respiration.Glycolysis (anaerobic)The citric acid cycleThe electron transport chain. (aerobic)

GlycolysisEnergy used and made in glycolysisTakes 2 ATP to start glycolysisOnly 4 ATP are produced4-2= 2 ATP gained (not very effective)Glycolysis uses an electron carrier called NAD+.NAD+ forms NADH which it accepts 2 electrons.GlycolysisGlycolysis is a series of chemical reactions in the cytoplasm of a cell that breaks down glucose into 2 molecules of pyruvic acid.Glucose 2 pyruvic acidGlucose is a 6 carbon molecule.Pyruvic acid is a 3 carbon molecule.

GlycolysisBefore citric acid cycle and electron transport chain stages begin, pyruvic acid undergoes a series of reactions in which it gives off a molecule of CO2 and bines with a molecule called coenzyme A to form acetyl-CoA.

The citric acid cycleOccurs in the mitochondria Citric acid cycle also called Krebs cycleFor every turn of the cycle, 1 ATP molecule of ATP and 2 molecules of carbon dioxide are produced.NAD+ and FAD+ (electron carriers) form NADH and FADH2 (carry electrons to electron transport chain)

Electron Transport chainOccurs in the inner membrane of the mitochondrion.Energized electrons are carried by NADH and FADH2 to the top of the chain. The electrons are passed from protein to protein within the membrane, slowly releasing their energy in steps. Some of that energy is used directly to form ATP.Electron Transport ChainThe final electron acceptor at the bottom of the chain is oxygen, which reacts with four hydrogen ions (4H+) and four electrons to form two molecules of (H2O). This is why oxygen is so important to our bodies. Without oxygen, the proteins in the electron transport chain cannot pass along the electrons. Electron Transport ChainIf a protein cannot pass along an electron to oxygen, it cannot accept another electron. Very quickly, the entire chain becomes blocked and ATP production stops.Overall, the electron transport chain add 32 ATP molecules.Aerobic process of ATP is very effective.

Other ways to make ATPFermentationFermentation occurs after glycolysis.Is a process of making ATP when there is no oxygen present. (Anaerobic process)Ex. Happens during heavy exercise, when your cells are without oxygen for a short period of time.FermentationThere are two major types of fermentationLactic acid fermentation2. Alcoholic fermentation

Lactic acid fermentationLactic acid fermentation is one of the processes that supplies energy when oxygen is scarce.Two molecules of pyruvic acid produced in glycolysis use NADH to form two molecules of lactic acid. This releases NAD+ to be used in glycolysis, allowing 2 ATP molecules to be formed for each glucose molecule. Lactic acid fermentationThe soreness feeling you get after you workout is due to the build up of lactic acid in the muscles cells. The lactic acid is transferred from muscle cells, where it is produced during strenuous exercise, to the liver that converts it back to pyruvic acid.Alcoholic fermentationIs used by yeast cells and some bacteria to produce CO2 and ethyl alcohol.

Ex. When making bread, yeast cell produce CO2 that forms bubbles in the dough.