Cellular respiration
- 1. Getting energy to make ATP Cellular Respiration The process by which mitochondria break down food molecules to produce ATP is called cellular respiration. There are 3 stages of cellular respiration. 1. Glycolysis (anaerobic) 2. The citric acid cycle 3. The electron transport chain. (aerobic)
- 2. Glycolysis Energy used and made in glycolysis Takes 2 ATP to start glycolysis Only 4 ATP are produced 4-2= 2 ATP gained (not very effective) Glycolysis uses an electron carrier called NAD+. NAD+ forms NADH which it accepts 2 electrons.
- 3. Glycolysis Glycolysis 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 acid Glucose is a 6 carbon molecule. Pyruvic acid is a 3 carbon molecule.
- 4. Glycolysis • Before 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.
- 6. The citric acid cycle • Occurs in the mitochondria Citric acid cycle also called Krebs cycle For 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)
- 8. Electron Transport chain • Occurs 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.
- 9. Electron Transport Chain • The 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.
- 10. Electron Transport Chain • If 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.
- 12. Other ways to make ATP Fermentation Fermentation 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.
- 13. Fermentation • There are two major types of fermentation 1. Lactic acid fermentation 2. Alcoholic fermentation
- 14. Lactic acid fermentation • Lactic 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.
- 15. Lactic acid fermentation • The 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.
- 16. Alcoholic fermentation • Is 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.