Glycolysis, Krebs, and ETC

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Glycolysis, Krebs, and ETC!
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Things to know

• Making ATP ultimately base on food source
  breakdown (usually sugar)
• Begins with GLYCOLYSIS
• If no oxygen present continues to-anaerobic
  fermentation
• Lactic acid fermentation
• Alcohol fermentation
• If oxygen present-continues to KREBS cycle (AKA
  Citric Acid Cycle or TCA cycle) then ETC

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Glycolysis

• In cytoplasm
• Glucose is OXIDIZED (leo) to pyruvate
• Major steps
• Glucose gains 2Ps from 2 ATP molecules-become
  fructose, 1-6 diphosphate
• F1-6 split into (2)3 carbon G3P-FIRST ½ DONE
• NAD takes an H off each G3P (so another P can be
  attached) 2 Ps on each 3Carbon molecule
• Both Ps ripped off both 3 carbon molecules (ADP-gt
  ATP)-
• (2) 3 carbon molecules (pyruvate) left

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Summary of Glycolysis

• 2 ATPs used-4 made per glucose
• Net?
• 4 ATPs are made from substrate level
  phosphorylation (get P from substrate)
• NAD-gt NADH

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What Happens NEXT?

• Depends on organism and availability of oxygen
• If none presentfermentation
• Fermentation itself produces no energy.
• Whats its point?

LA fermentation
alcohol fermetation
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LA vs Alcohol ferm

• In animals, some microbes
• Pyruvate accepts H from 2 NADH molecules?lactic
  acid (3 carbon)
• Lactic acidsore

• Microbes like bacteria, yeast
• Pyruvate loses CO2 and accepts H from 2 NADH?
  ethanol (2 carbon)

Some microbes are ANAEROBIC-can't tolerate oxygen
facultative anaerobe-can do ferm or aerobic
respiration
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IF oxygen present after GlycolysisKREBS!

• In mitochondria
• It IS a cycle
• Pyruvate loses CO2-becomes 2C Acetyl CoA
• Acetyl CoA joined w/4 Carbon cmpd
• 6 C compoud loses CO2 and H to become a 5C cmpd,
  the 4 C again
• 4C cmpd recycled again
• Released Hs-carried by NADH and FADH to ETS!

ATP
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Krebs summary

• NAD and FAD pick up released Hs
• ADP P make ATP- substrate level phosphorylation
• CO2 released
• Where do they go?
• NADH H and FADH2 bring their H to ETC
• CO2exhale!

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ETC-Electron Transport Chain

• Sometimes called oxidative phosphorylation (P is
  not coming from a substrate)
• Intermembrane space of mitochodria

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ETC

• NADH FADH2 drop their H and electrons off at
  protein carriers w/in membrane
• Electrons flow thru chain-reaching higher energy
  levels as they travel
• Hpumped outside membrane
• Haccumulates outside

electron carriers
protein complexes
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ETC continued

• Oxygen accepts 2 electrons from chain and 2 H
  from surroundings
• What does this make?
• H now in higher conc. Outside membrane-moves
  back in via ATP synthase (Like an H water
  wheel-makes energy)-called chemiosmosis
• Energy make joins ADP PATP

overall equation-glycolysis ETC
glucose oxygencarbon dioxide water 36 ATP
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Poisons can stop respiration

• Block ETC
• Rotenoneblocks e- from traveling past 1st
  carrier
• Cyanide and Carbon Monoxideblock electrons in
  3rd carrier from binding to oxygen
• Block ATP synthase
• -oligomycin-blocks H from entering

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Poisons contd

• Uncoupling Agents-destroys chemiosmotic
  gradient-moves H BACK into mito thru membrane,
  not synthase
• - 2,4-Dinitrophenol-former diet pill!