Transcript Cellular Energy hbio 09 tri 1

Starter
Light Energy
6CO2 + 12H2O  C6H12O6 + 6H2O + 6O2
Enzymes
C6H12O6 + 6H2O + 6O2  6CO2 + 12H2O + energy
1. Write down these equations.
2. Label each equations for which process it represents.
3. How do they relate?
1. With the person sitting next to you put the items on the worksheet in
categories and write down what each item in the category shares in
common.
2. Why did you put them in those categories and what do they have in
common.
Cellular Energy
Main Energy Pathways
• Anaerobic
– No oxygen
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Fermentation
Anaerobic electron transfer
Cytoplasm
Other than O2 as final e- acceptor
• Aerobic
– With oxygen
– Dominant
– Mitochondria
– O2 as final e- acceptor
Overview – Aerobic Respiration
• Most ATP from Glucose
– 36 or more
• C6H12O6 + 6H2O + 6O2  6CO2 + 12H2O + ENERGY
• 3 reaction stages
– Glycolysis
– Krebs Cycle
– Electron transfer chain
3 stage overview
• Glycolysis
– Enzymes cleave and rearrange a glucose
molecule into 2 molecules of pyruvate (3
carbon)
• Krebs Cycle
– Enzymes break down pyruvate to CO2 and H2O
• Releasing H+ and e-
• Electron transfer chain
– Most energy
– H+ and e- gradients
• Drive ATP formation
– O2 inside mitochondria accepts the “spent” eand H+ to form H2O
Glycolysis: Stage 1
• All energy-releasing pathways start with this
reaction in the cytoplasm
• Glucose
– Simple sugar
• C6H12O6
• Glucose  2 pyruvate
• Energy Requiring
– 2 ATP
• Transfer a phosphate to glucose
– Phosporylation
» Increase the energy level of glucose
• 4 ATP Produced
• Net Gain of 2 ATP
2nd Stage: Krebs Cycle
• AKA – Citric Acid Cycle
• Mitochondrion
– 2 Pyruvate molecules
• Preparatory process
– Carbon removed from each pyruvate
• Coenzyme A (CoA)2 carbon fragmentacetyl-CoA
– Enters Krebs cycle
• Overview
– Completely break down Pyruvate molecules
• CO2 and H2O
– 2 ATP
– Transfer of e- and H+
• 6 Carbons enter
• 6 Carbons leave
2nd Stage: Krebs Cycle
• 3 Functions
– First
• Loads e- and H+ onto NAD+ and FAD
– NADH and FADH2
• Organic Carbons into CO2
– Second
• Forms 2 ATP
– Third
• Rearranges intermediates to keep it going
Totals before the 3rd stage
• Glycolysis =
2 NADH
• Pyruvate Conv. =
2 NADH
• Krebs =
2 FADH2 + 6 NADH
__________________________________
• Total =
2 FADH2 + 10 NADH
• 4 ATP Produced
Third Stage: ETC
• ATP formation = high gear
– e- transfer chains and ATP synthase
– Inner membrane of mitochondrion
• Electron Transfer Chains
– e- enter ETC via NADH and FADH2
• Release H+
– e- through ETC
• H+ in the matrix (inner most part of mitochondrion)  Intermembrane
space
– [H+] gradient
– H+ follow concentration gradient
• Move out of matrix into the intermembrane space
– ATP Synthase
» ADP + Pi  ATP
– Free O2 clears ETC
• Spent e• Combines with H+
– H2O
Energy Harvest
• 36 total
– 32 ATP in ETC
– 4 from first 2 stages
• Production varies
– NADH (glycolysis)
• Can’t get in
– Donates e- and H+
» NAD+  highest energy level  3 ATP
» FAD  lower energy level  2 ATP
– Heart & Kidney
• NAD+ = 38 ATP
– Skeletal and Brain
• FAD = 36