How does the cell produce ATP?Substrate-level phosphorylationOxidative phosphorylationNAD+ & FAD are CoenzymesOverview of glucose oxidationSlide 6GlycolysisThe Krebs CycleHow pyruvate enters the matrix?Pyruvate is first converted to Acetyl CoALets see the Krebs cycleKrebs CycleWhat the cell earns from the Krebs cycle?Slide 14Summary of Glucose OxidationWhat has the cell obtained from each molecule of glucose?What happens to the NADH and FADH molecules produced?Slide 18Slide 19Slide 20Slide 21Slide 22ATP SynthaseCellular RespirationSlide 25Slide 26How fermentation occurs in humans?Slide 28How does the cell produce ATP?Substrate-level phosphorylationOxidative phosphorylationNAD+ & FAD are Coenzymes •Coenzymes: –Are small organic molecules–They act by accepting electrons from an enzymatic reaction and transferring those electrons to a different reaction•NAD+ (nicotinamide adenine dinucleotide)–Is derived from niacin (vitamin B3)–NAD+ + 2H  NADH + H1•FAD (flavin adenine dinucleotide)–Is derived from riboflavin (Vitamin B2)–FAD + 2H  FADH2Overview of glucose oxidationThe molecule is being splitGlycolysis•Energy produced: 4 ATP•Energy spent : - 2 ATP•Net energy gained: 2 ATP•Other molecules obtained:–2NADH–2 PyruvateThe Krebs Cycle•In bacteria and archae, the Krebs cycle occurs in the cytoplasms.•In eukaryotes, the pyruvate produced during glycolysis is transported to the mitochondria.How pyruvate enters the matrix?•An active transport protein called pyruvate carrier carry the pyruvate molecule to the matrix.–This active transport protein is located in the inner membrane of mitochodrion.Pyruvate is first converted to Acetyl CoA•Co-enzyme A acts by accepting and transferring an acetyl group (-COCH3) to a substrate.–The A in CoA stand for acetylation.–Acetyl group is often bounded to a sulfur (S)atom.Lets see the Krebs cycleKrebs Cycle1 ATP4 NADH1 FADH23 CO2ATPNADHNADHNADHNADHCO2CO2CO2What the cell earns from the Krebs cycle?•1 ATP molecule•4 NADH molecules•1 FADH2 molecule•3 CO2 molecules•These amounts must be multiplied by 2, Why?Because during Glycolysis two molecules of pyruvate are producedSummary of Glucose OxidationWhat has the cell obtained from each molecule of glucose? •10 molecules of NADH•2 molecules of FADH•4 ATPs•The ATP molecules obtained in the oxidation of glucose are the result of substrate-level phosphorylation.What happens to the NADH and FADH molecules produced?•NADH and FADH2 carry electrons that are going to drive the redox reactions that will result in the production of a high amount of ATP molecules.•The electrons that they carry will be transferred to the electron transport chain in which oxygen will be the final electron acceptor molecule producing water.Drops in free energy are couple with the production of ATP, NADH, FADH2•During glycolysis and the Krebs cycle, the free energy of previous compound involves drops.–Sometimes, it drops in small step (they a couple with the production of ATP)–Other times it drops in large steps (its couple with the production of NADH and FADH2What will happen if the final acceptor (oxygen) is not present in the cell?•If oxygen is not present in the cell, cellular respiration can’t occur.•Instead, an alternative pathway called fermentation reactions takes over.Using poisons researchers figured out the sequence of the molecules in the electron transport chain•NADH donate an electron to a flavin containing protein.•FADH2 donates its electrons to an iron-sulfur containing protein that passes it directly to QElectron-Transport Chain is composed of four large protein complexes and cofactorsflavin groupiron-sulfurhemeubiquinone•Protons are pumped by three of the complexes.•Q and protein cytochrome c acts as shuttles that transfer electrons between complexes.http://vcell.ndsu.nodak.edu/animations/etc/movie.htmC:\Users\Angel\Desktop\chapter26\Animation\electron_transport_and_.swfElectron-Transport Chain is composed of four large protein complexes and cofactorsATP Synthase•http://vcell.ndsu.nodak.edu/animations/atpgradient/movie.htmChemiosmosisCellular RespirationFermentationHow fermentation occurs in humans?In humans, fermentation produce lactic acidIn the fungus Saccharomyces cerevisiate (yeast) alcohol fermentation