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Cell Respiration What is Cell Respiration? Its related to the respiratory system in that the lungs bring in the oxygen needed for cell respiration Oxygen goes in Carbon dioxide goes out How does the Oxygen change to CO2 ?? Process happens at cellular level In the alveoli of the lungs, O2 is exchanged for CO2 into the capillaries by diffusion The circulatory system brings the oxygen to the cells In the capillaries, O2 diffuses into cells and CO2 diffuses out The circulatory system also brings Sugar (glucose) to the cells So sugar and oxygen are delivered to cells Cellular Respiration The complex process of cells “burning” sugar (glucose) with oxygen to form usable energy (ATP) There are 2 types of cell respiration Aerobic – Occurs in presence of oxygen Anaerobic – Occurs without oxygen Aerobic cell respiration The “Usual” process of respiration Aerobic means “air” Occurs with oxygen Produces up to 38 ATP per glucose Anaerobic respiration Occurs without oxygen Produces only 2 ATP per glucose Fermentation is anaerobic Fermentation Yeast and some bacteria obtain energy through anaerobic respiration Fermentation forms Alcohol, Vinegar or Lactic acid Bacteria can only use fermentation Prokaryotes have NO Membrane organelles No mitochondria Lactic acid can form from over exercise or lack of training Not enough oxygen can cause painful lactic acid build up in muscles In Eukaryotic cells, Aerobic respiration occurs in the mitochondria Respiration Reaction: Sugar + O2 CO2 + H20+ Energy (ATP) (glucose) Respiration is the opposite of Photosynthesis Photosynthesis In Chloroplasts CO2 + H2O + SUN Sugar + O2 Respiration In Mitochondria Sugar + O2 CO2 + H2O + ATP Respiration occurs in both plants and animals 3 Stages of Cell Respiration: 1) Glycolysis 2) Krebs cycle 3) Electron transport chain 1) Glycolysis Occurs in the cytoplasm Glucose breaks into 2 pyruvates and forms 2 ATP. C-C-C-C-C-C C-C-C + C-C-C + 2 ATP ATP synthesis by Substrate level phosphorylation Glycolysis uses 2 ATP to gain 4ATP - 2ATP + 4ATP Net 2 ATP Substrate level Phosphorylation ATP phosphorylated (phosphate added) by substrate PEP 2 NADH also produced in Glycolysis NAD+ is reduced with eand gains a H+ e NAD+ + H+ NADH It can be oxidized later into ATP in ETC Energy overview glycolysis Each Pyruvate must become Acetyl CoA to enter Krebs cycle Each pyruvate forms 1 NADH = 2 per glucose 2) Krebs Cycle Also called Citric acid cycle Occurs in the Mitochondria Pyruvate is broken into C02 molecules Energy molecules form (2 ATP, 6 NADH and 2 FADH2 ) 2 C-C-C + O2 6 CO2 + 2 ATP + 6 NADH + 2 FADH2 Each Acetyl CoA enters Krebs separately. Adds 2 carbons to a 4 carbon (oxaloacetate) Acetyl CoA + Oxaloacetate Citrate + CoA Products of One Krebs Cycle 2 C02 3 NADH 1 ATP (substrate level Phos.) 1 FADH2 Products from 1 glucose molecule Each Acetyl CoA must go around cycle Two turns per glucose molecule TOTALS From 1 glucose 4 C02 6 NADH 2 ATP (substrate level Phos.) 2 FADH2 3) Electron Transport Chain (system) Occurs in the inner Mitochondria membrane NADH and FADH2 are Oxidized (lose electrons) to form 34 ATP Oxygen is used up (final electron acceptor) Water is produced from H+ and OH- ETC molecules : Energy molecules NADH and FADH2 carry H+ and e- to Inner Mito. membrane where there are a lot of protein complexes ETC electron flow Electrons flow along protein chain in inner membrane At End, Oxygen accepts electrons forming water 1st - NADH and FADH2 are oxidized Electrons are removed from them releasing energy which is used to pump H+ into the inner membrane space Later -Oxygen is the final acceptor of these electrons which will produce water 2nd - Protons pumped out across membrane Proton pump sets up gradient by chemiosmosis Chemiosmosis is the diffusion of ions across a selectivelypermeable membrane. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration. 3rd - ATP formed by Oxidative phosphorylation in electron transport chain ATP synthase phosphorylates using proton gradient pump in inner mitochondrial membrane OXIDATION NOT substrate level phoshorylation 4th - Oxygen At end of ATP phosphorylation, Oxygen accepts the electrons from the ETC and combines with the H+ ions and forms water as a by product of respiration ATP amounts NADH – forms 3 ATP each FADH2 – forms 2 ATP each Note – NADH produced in cytosol must use one ATP to transport into mitochondria ATP calculation Why is second chart different? Animation ETC Electron transport http://vcell.ndsu.edu/animations/etc/movie-flash.htm ATP synthase http://vcell.ndsu.edu/animations/atpgradient/movieflash.htm QUIZ What are the 3 stages of cell respiration? 1) Glycolysis Purpose – Split glucose into pyruvate, form 2 ATP 2) Krebs Cycle Purpose – Form CO2, form NADH, FADH +ATP 3) Electron transport chain Purpose – Use NADH + FADH2 to form ATP + H2O