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Cellular Respiration

Cellular Respiration. Stage 1: GLYCOLYSIS. Overview of Glycolysis. Glycolysis = “sugar splitting” 1o reactions that occur in the cytosol Each step is catalyzed by a specific enzyme OVERALL: Glucose (__C)  two pyruvate (__C each). Glycolysis in Detail. YIKES! We will break

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Cellular Respiration

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  1. Cellular Respiration Stage 1: GLYCOLYSIS

  2. Overview of Glycolysis • Glycolysis = “sugar splitting” • 1o reactions that occur in the cytosol • Each step is catalyzed by a specific enzyme • OVERALL: Glucose (__C)  two pyruvate (__C each)

  3. Glycolysis in Detail • YIKES! • We will break each step down, and then summarize the main points.

  4. Step 1: ATP _____________glucose to glucose 6-phosphate Glucose 6-phosphate (G6P): _____________________ ________________________________________________. MAIN REACTANT(S): ________________ ATP INVOLVED (+ or -): ______________________ PRODUCTS: _________________

  5. Step 2: G6P is rearranged to fructose 6-phosphate (F6P) Fructose 6-phosphate: __________________________ ________________________________. Carbon 1 becomes ________________ from the ring structure. MAIN REACTANT(S):___________________ ATP INVOLVED (+ or -):______________________ PRODUCT(S):____________________________

  6. Step 3: ATP _____________F6P to fructose 1,6-bisphosphate F 1, 6-BP: _______________________________________ _______________________________________________ Importance?:___________________________________ MAIN REACTANT(S): ______________________ ATP INVOLVED (+ or -): __________________________ PRODUCTS: _________________________

  7. Steps 4&5 - cleavage 4) F 1,6-BP split into DHAP and G3P 5) DHAP immediately converted into G3P by an isomerase enzyme. Therefore, ______ molecules of ______ formed. Importance?:___________________________________________. MAIN REACTANT(S): ______________________________ “INTERMEDIATE REACTANT(S): ____________________ __________________________________________________ ATP INVOLVED (+ or -): _____________________________ PRODUCTS: ___________________________________________

  8. Let’s review steps 1-5... • ____ ATP molecules are used in the first 5 steps of glycolysis. One is used in step ____ and one is used in step ____. In both of these reactions, _____________ groups are added to the initial _______________ molecule. This prepares the molecule for ___________. • In step ____, ____________________ is split into __________________________________. • The ____________________ enzyme immediately converts _____________ into _________________, resulting in two molecules of _________________. • There are now ____ G3P molecules for each __________ molecule entering glycolysis.

  9. “DOUBLING” THE REACTION... STEPS 6-10 HAPPEN EXACTLY THE SAME WAY FOR EACH OF THE __________ MOLECULES.

  10. Step 6: ADehydrogenase enzyme * catalyzes two sequential reactions: • NAD+ + 2e- + 1P  NADH • Adds Pi from cytosol to G3P. For each Glucose Molecule: MAIN REACTANT(S):________________________________________ ATP INVOLVED (+ or -): :_____________ Energy-Harvesting Product(s):___________________________________ PRODUCT(S):_______________________________________________ Regina Bailey, http://biology.about.com/ od/cellularprocesses/a/aa082704a.htm

  11. Step 7: ATP is FINALLY PRODUCED! • ATP molecules are produced by substrate-level phosphorylation (one for each ____________molecule) • 1,3-bisphosphoglycerate (BPG) is converted into 3-phosphoglyerate (3PG) What happened? ______________ ______________________________. MAIN REACTANT(S):_________________ ATP INVOLVED (+ or -):_____________ Energy-Harvesting Product(s):_____________________________ PRODUCT(S):_______________________________________________

  12. Step 8: • Rearrangement of the phosphate group from C3 to C2 • MAIN REACTANT(S):_________________ • ATP INVOLVED (+ or -):_____________ • Energy-Harvesting Product(s):_____________________________ • PRODUCT(S):_______________________________________________

  13. Step 9: • 2PG is converted to PEP by removal of water molecule MAIN REACTANT(S):_________________ ATP INVOLVED (+ or -):_____________ Energy-Harvesting Product(s):_____________________________ PRODUCT(S):_______________________________________________

  14. Step 10: Two ATP molecules are formed by substrate-level phosphorylation. • PEP is converted to pyruvate MAIN REACTANT(S):_________________ ATP INVOLVED (+ or -):_____________ Energy-Harvesting Product(s):_____________________________ PRODUCT(S):_____________________________________________

  15. ... OVERALL... ENERGY YIELD: ____ ATP USED ____ ATP PRODUCED ____ NADH PRODUCED ---------------------------- net: ____ ATP PRODUCED ____ NADH PRODUCED Note: ATP may be used immediately by the cell. NADH will be further processed to make more ATP.

  16. Energy Conversion Efficiency of Glycolysis • For each mole of glucose produced: Glycolysis transfers only about 2.2% of the free energy available in 1 mol of glucose to ATP.

  17. Only 2.2% conversion efficiency?! • Majority of energy is still trapped in the two ____________________________ molecules and two _____________ molecules.

  18. Glycolysis and Life... • Glycolysis can be aerobic or anaerobic • The first cells probably used this process to harness energy, and today, the simplest organisms continue to use it for all their energy needs. • YIELD: ____ ATP molecules for every ____ glucose. • This may be enough energy for the needs of some _________________ organisms, but it is not enough for _________________ organisms. • All organisms carry out glycolysis.

  19. Glycolysis is only the beginning of cellular respiration... • Don’t spend a lot of time studying the ‘little things.’ • You should look over the whole process, and identify what is important. • What are some important steps/processes? • INITIAL REACTANTS, ENERGY USED, ENERGY EXPENDED, REARRANGEMENTS OF MOLECULES, NUMBER OF MOLECULES INVOLVED. • You do not need to memorize the names of the intermediate molecules.

  20. Classwork/Homework Read pg 99-100 Section: “Mitochondria” Answer the following questions: • The process that produces ATP in mitochondria cannot proceed without ______________________. • What are the three stages of cellular respiration that occur within mitochondria? • Only _________________ contain mitochondria. • Where do prokaryotic cells carry out cellular respiration? Why? • A double membrane is referred to as an ______________. Where else have you seen this term? • The folds of mitochondria’s inner membrane are called ______________. It contains many _________________ and ___________________ imbedded in its _______________________ that participate in the reactions of respiration. • The mitochondrial matrix is a _____________________ liquid that fills the ______________________ space of a mitochondrion. • A fluid-filled ___________________________ lies between the inner and outer membrane. • What is the endosymbiosis hypothesis? What component of mitochondria helped strengthen this theory? WORK ON THE GLYCOLYSIS HANDOUT. FINISH IT FOR TOMORROW.

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