Presentation on theme: "Cellular Respiration 7.1 Glycolysis and Fermentation 7.2 Aerobic Respiration."— Presentation transcript:
1Cellular Respiration7.1 Glycolysis and Fermentation Aerobic Respiration
2Cell RespirationLiving cells constantly use energy for activities such as movement, protein synthesis, active transport and cell division.Most of the energy to power these processes comes from ATP.A cell must constantly replace ATP
3The cell does this by breaking down organic food molecules The cell does this by breaking down organic food molecules. Releasing energy that is used to join ADP and phosphate to form ATPThe breakdown of food to release energy occurs by 2 kinds of processes:1. respiration 2. fermentation
4Cell RespirationA fuel molecule such as glucose is oxidized to form carbon dioxide and water.Energy is captured through the formation of up to 36 to 38 ATPs per glucose molecule
5It is the process by which cells extract fee energy from the energy stored in chemical bonds of food molecules (glucose)This is done in a series of catabolic pathways featuring redox reactions and using oxygen as the final electron acceptor
6The energy released is used to regenerate the cell’s supply of ATP ATP donates the energy to various energy requiring processes such as metabolic reactions, active transport, muscle contractions, etc…
8Mitochondria Site of cell respiration Most ATP production occurs here Parts of the Mitochondria:1. Cristae: folds of mitochondria is where electron transport occurs2. Matrix: open area of mitochondria, where kreb cycle occurs3 Cytosol: outside mitochondria , where glycolysis occurs.
12Glycolysis Occurs in cytosol outside mitochondria Converts the 6-carbon glucose into 2 3-carbon pyruvic acid molecules4 ATP are make, but due to a deficiency of 2 ATP, the step generates a positive 2 ATPIf oxygen is present then the reaction proceeds to kreb cycle
13If oxygen is absent, it will proceed to fermentation Fermentation occurs in the cytosol, has a net gain of 2 ATP per glucose and is only 2.1% efficientBetween glycolysis and kreb cycle is a transition reaction in which pyruvate ( pyruvic acid) is converted to acetyl CoA and 2 CO2 are removed
16Kreb Cycle Is located within the mitochondria matrix Also called Citric acid cycle, or TCACompletes glucose oxidation by breaking down a pyruvic acid derivative (acetyl CoA) into carbon dioxideIs a circular sect of reactions because the reaction is ongoing, never reaching an endpoint.
17Requires 2 turns of the kreb cycle per glucose ( each turn releasing 2 carbon dioxides, 3 NADH, 1 ATP, 1 FADH2NADH and FADH2 are coenzymes (NAH accepts 2 electrons and 1 hydrogen while FAD accepts 2 electrons and 2 hydrogen)
20Oxidative phosphorylation Accounts for most ATP produced during respiration (32 to 34)Includes electron transport chain made of electron carriers molecules built into the inner mitochondrial membraneOxygen pulls energized electrons harvested during glycolysis and kreb cycle down the electron transport chain to a lower energy state.
21This exergonic slide of electrons is coupled to ATP synthesis Electron transport accepts electrons from glucose during glycolysis and transition reaction and kreb cycle… usually NAD+ carries these electrons
22The electrons then drop off the supply of energy needed to pump the hydrogen ions from the matrix to the intermembrane space of the mitochondria ( this is chemiosmosis)The NAD+ and Fad then return to pick up more hydrogen ( both reusable)
23When NADH delivers electrons, it has enough energy to make 3 ATP. When FADH2 delivers electrons, it has enough energy to make 2 ATPCytochrome: the molecule that helps with electron transport
24Chemiosmosis: ability of some members to use hydrogen ion s gradient to drive ATP formation Oxidative phosphorylation: refers to the production of ATP as a result of energy released by electron transport system
25Electron Transport Chain of Aerobic Respiration protonsprotonsprotonsFADH2NAD+ADP + PhosphateO2
27Electron Transport Chain of Aerobic Respiration protonsprotonsprotonsFADH2NAD+ADP + PhosphateO2
28Energy Yield of Aerobic Respiration – * One glucose can generate up to 38 ATP molecules. * 38 x 12 kcal divided by 686 kcal = 66 % efficiency. * About 20 times more efficient than glycolysis alone. * Note: a car engine is only about 25 % efficient.
30Photosynthesis and Cellular Respiration (opposite reactions) * The final products of plant photosynthesis (sugar and oxygen) are used by animals for the process called cellular respiration. The products of respiration are carbon dioxide and water, which plants need for photosynthesis.* Since photosynthesis and respiration are opposite processes, they form a cycle that keeps the levels of oxygen and carbon dioxide fairly constant in the atmosphere.