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GLYCOLYSIS

GLYCOLYSIS. The first step of cellular respiration. What the LIP@SES is Glycolysis ?. The word glycolysis is constructed from glycose , an older term for glucose, and – lysis , which means breakdown. (Greek for “sugar splitting”)

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GLYCOLYSIS

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  1. GLYCOLYSIS The first step of cellular respiration

  2. What the LIP@SES is Glycolysis? • The word glycolysis is constructed from glycose, an older term for glucose, and –lysis, which means breakdown. (Greek for “sugar splitting”) • The metabolic pathway that converts glucose, C6H12O6 into pyruvate, CH3COCOO− + H+. • The products formed are adenosine triphosphate(ATP), and nicotinamide adenine dinucleotide (NADH)

  3. The 10 Steps of Glycolysis • Glycolysis is split up into 10 different steps. • In the first 3 steps, energy in the form of ATP is invested to be reused later. • In the next 2 steps, the energy allows glucose to be split into 2 smaller molecules. • In the last 5 steps, energy is released as ATP and NADH.

  4. Click Link for an Animation  http://www.johnkyrk.com/glycolysis.swf

  5. Step 1: ATP phosphorylates glucose to G6P • Hexokinase is an enzyme that uses ATP to phosphorylate glucose. • This investment of energy prepares glucose for releasing energy later on. • Results in Glucose 6-phosphate. • ADP is released. • FIRST STEP IS IRREVERSIBLE

  6. Step 2: G6P rearranged to F6P • The enzyme phosphoglucoseisomerase catalyzes the opening of the ring form of G6P into the open ring form. • Carbonyl group of G6P changes position from the 1st to the 2nd carbon on the chain. • Fructose 6-phosphate is formed by this reaction. • Phosphoglucoseisomerase catalyzes F6P into its ring form.

  7. G6P to F6P

  8.  You are HERE…

  9. Step 3: ATP phosphorylates F6P to F 1, 6-BP • Enzyme phosphofructokinase uses ATP to phosphorylate F6P. • ADP is released, and the molecule fructose 1, 6-bisphosphate is formed. • Steps 1-3 all include an investment of energy in the form of ATP that will be repaid in the later steps of glycolysis.

  10. F6P to F1,6BP

  11. Step 4: Splitting up F 1, 6-BP • Begins with the opening of the ring for of F 1, 6-BP into the open chain form. • The enzyme aldolase cleaves F 1, 6-BP into 2 molecules. • One molecule formed is glyceraldehyde 3-phosphate. • The other molecule formed is dihydroxyacetone phosphate.

  12. Cleaving the Hexose Ring

  13. Step 5: DHAP converted to G3P • The enzyme triophosphateisomerase catalyzes the isomerization of dihydroxyacetone phosphate (DHAP) into G3P. • This reaction is similar to step 2. • Result is 2 molecules of G3P. • These 2 steps break down the molecules formed in the first 3 steps into smaller molecules.

  14. DHAP to G3P

  15. Step 6: BPG and NADH Steps 6-10 are the energy generating stepsof glycolysis. NAD+ is used to oxidize G3P An inorganic phosphorus bond is connected to the molecule to form 1,3 biphosphoglycerate. Hydrogen atoms reduce NAD+ to NADH

  16. G3P to BPG

  17. Step 7: BPG to 3PG • The high energy phosphate group in BPG is dephosphorylated. • The phosphate group is transferred to ADP, which becomes ATP • The 3 carbon molecule is now 3-phosphoglycerate. • Reaction occurs twice, 2 ATP molecules generated. The energy usage has been paid back.

  18. BGP to 3GP

  19. Step 8: 3PG rearranged to 2PG • 3-phosphoglycerate is transformed by an enzyme into 2-phosphoglycerate.

  20. 3GP to 2PG

  21. Step 9: 2PG converted into PEP • Enzyme removes a water molecule from 2-phosphoglycerate, creating phosphoenolpyruvate. • The loss of the water molecule redistributes the energy within the molecule. • Creates phosphate group with high free energy of hydrolysis.

  22. 2PG to PEP

  23. Step 10: PEP converted to pyruvate • Enzyme transfers the phosphate group from PEP into ADP, creating ATP and pyruvate.

  24. PEP to Pyruvate

  25. Summary • In the first part of glycolysis, ATP is invested to be used later. • In the second part, the bigger molecules are split up into smaller ones. • In the third part, many of the reactions release energy in the form of ATP and NADH. • Net energy: 2 ATP molecules and 2 NADH molecules.

  26. http://www.youtube.com/watch?v=O5eMW4b29rg

  27. Mitochondria • Mitochondria (singular: mitochondrion) sausage shaped organelles that are usually scattered through a cell’s cytoplasm. • Glycolysis takes place in the cytoplasm. • Pyruvate oxidation, the Krebs cycle, and electron transport and chemiosmosis take place in the mitochondria. • Only eukaryotic cells contain mitochondria

  28. Mitochondria

  29. Mitochondria • Mitochondria possess a double membrane; a smooth outer membrane and a folded inner membrane. • Folds of inner membrane called cristae • Mitochondrial matrix is a protein-rich liquid filling the innermost space of a mitochondrion. • Mitochondrion possess their own DNA, called mtDNA, RNA, and ribosomes.

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