exam next friday
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Exam next Friday. Proposal: 60 point 4 th exam over chapters 10 (Lipids), 11 (Membranes), 13 (Bioenergetics (ATP & redox) 140 point final: ~40 points new stuff (general concepts in glycolysis, TCA, electron transport), ~100 points “comprehensive” Review sheet (4 th exam) this weekend - PowerPoint PPT PresentationTRANSCRIPT
Exam next Friday
• Proposal: – 60 point 4th exam over chapters 10 (Lipids),
11 (Membranes), 13 (Bioenergetics (ATP & redox)
– 140 point final: ~40 points new stuff (general concepts in glycolysis, TCA, electron transport), ~100 points “comprehensive”
– Review sheet (4th exam) this weekend– Review for 4th exam on Tuesday(?)– Review for final ~ couple of days next week
Nutrients:Fats/Carbohydrates/Proteins (highly reduced compounds)
Usable (bioavailable) chemical energy:ATP (other phosphorylated cpds), reducing agents (eg. NADH)
Glycolysis, TCA/Krebs cycle Breakdown of nutrients Harvesting of energy as (some) ATP, lots of reducing power (NADH)
Oxidative phosphorylation (Electron transport) Harvesting of energy from reducing agents Generation of (lots of) ATP
Aerobic respiration of glucose (etc)
• Glycolysis: – Start with glucose (6 carbon)– Generate some ATP, some NADH, pyruvate (2 x 3 carbon)
• TCA cycle– Start with pyruvate– Generate acetate– Generate CO2 and reduced NADH and FADH2
• Electron transport – Start with NADH/FADH2
– Generate electrochemical H+ gradient• Oxidative phosphorylation
– Start with H+ gradient and O2 (and ADP + Pi)– Generate ATP and H2O
Glycolysis• Pathway for D-glucose
degradation• Generation of pyruvate• Anerobic (no O2 required)
– Occurs in most every living cell– Eukaryotes→ in cytosol
• Pyruvate has different fates– Aerobic→CO2→ ATP– Anerobic
• Fermentation to EtOH• Fermentation to lactate
Glycolysis
• 5 step preparatory phase– Energy requiring– 2 ATP invested
1. Phosphorylation
2. Isomerization
3. Phosphorylation
4. Cleavage
5. Isomerization
Why phosphorylation?
1. Coupled transfer of phosphate to/from ATP
2. Intermediates “trapped” within the cell• Energy required to keep ‘naked’ glucose in the cell
(vs. chemical gradient)• Phosphate groups (neg charge) easily retained
3. Binding energy • Enzymes take advantage of negative charge to
increase affinity/specificity
Glycolysis• 5 step payoff phase
– 4 ATP generated (net 2 gained)
– 2 NADH gained– 2 pyruvate– Series of oxidation
and phosphorylation steps
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Step 1: Glucose phosphorylation by hexokinase
Step 2: Conversion to Fructose-6-P
Step 3:Phosphorylation to F-1,6-bisP
phosphofructokinase
*Committed step*Regulatory enzyme
Step 4: Cleavage of F-1,6-bP
6 carbon sugar →Two 3 carbon sugars (triose phosphates)
Step 5: isomerization of dihydroxyacetone
Both 3 carbon sugars arenow the same(glyceraldehyde 3-P)
“Payoff phase”Step 6: oxidation
(phosphorylation) of G-3-P
Step 7: ATP formation
Steps 6 & 7
Overall: transfer of Pi from glyceraldehyde 3-P to ATP with1,3-BPG as an intermediate
“Substrate-level phosphorylation”
Step 8: Rearrangement to 2-phosphoglycerate
Step 9: Dehydration of 2-phosphoglycerate to PEP
Step 10: Phosphoryl transfer to ADP