Lecture 6 Outline (Ch. 9)
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Transcript of Lecture 6 Outline (Ch. 9)
Lecture 6 Outline (Ch. 9)
I. Overview of Respiration
II. Redox Reactions
III. Steps of Respiration
IV. Cellular Respiration
A. Glycolysis
B. Coenzyme Junction
C. Citric Acid Cycle (aka Krebs/TCA cycle)
D. Electron Transport Chain (ETC)
E. Chemiosmosis
V. Anaerobic respiration
VI. Respiration using other biomolecules
VII. Lecture Concepts
Cellular Respiration
Overall purpose:
• convert fuels to energy
• animals AND plants
• complementary to photosynthesis
Cellular Respiration:(Exergonic)
Cellular Respiration
• catabolizes sugars to CO2
• requires O2
• at mitochondrion
Redox Reactions
• as part of chemical reaction, e- are transferred
• e- transfer = basis of REDOX reactions(reduction) (oxidation)
Redox Reactions
• follow the H, e- w/them
Redox Reactions
Equation for respiration
• transfer of e- to oxygen is stepwise
Redox Reactions
• e- moved by NAD+ (niacin)
• when “carrying” e- (& H+), NADH
Where do e- come from?
• gained e- (& H+), reduced
• food (glucose)
Where do e- go?
• glucose NADH ETC O2 (H2O)
Redox Reactions
1. glycolysis
- cytosol
- mitochondrial matrix
- inner mitochondrial membrane
• Steps of respiration:
2. Citric acid cycle
3. ETC
4. Chemiosmosis - inner membrane to intermembrane space
Steps of Respiration
Coenzyme Junction
• Stages of respiration:
1. Glycolysis – prep carbons
Cellular Respiration
1. Glycolysis
• 1 glucose (6C) 2 pyruvate (3C)
• key points: - inputs
- NAD+/NADH
- ATP
Cellular Respiration
- CO2 and H2O
- outputs
• eukaryotes AND prokaryotes
-inputs:
CO2 none
2 H2O
-outputs:
1 Glucose
2 ATP
4 ATP (2 net)
2 NADH
2 pyruvate
Where do they go?
Glycolysis Cellular Respiration
Coenzyme Junction • 2 pyruvate (3C) 2 Acetyl CoA (2C)
Cellular Respiration
• pyruvate joins coenzyme A (vitamin B)
• 2 C lost (as CO2)
• 2 NAD+ NADH
Steps of Respiration
• Stages of respiration:
2. Citric acid cycle e- transfer: redox
Cellular Respiration
2. Citric acid cycle
• 2 Acetyl CoA (2C) join oxaloacetate (4C)
• few ATP so far
• e- to carriers
(NAD+, FAD)
• mitochondrial matrix
• 2 citrate (6C) converted several steps, 4C lost (CO2)
-inputs:
4 CO2
H2O none
-outputs:
2 Acetyl CoA (2C)
2 ATP
6 NADH
2 FADH2
[2 oxaloacetate (4C)]
Where do they go?
Citric acid cycle
Self-Check
Step of Respiration
Inputs Outputs CO2/H2O ATP produced
e- carriers loaded
Glycolysis 1 glucose 2 pyruvate 2H2O 2 net 2 NADH
Coenzyme Junction
Citric Acid Cycle
Electron Transport Chain
Oxidative phosphorylation
Fermentation
1. glycolysis
- cytosol
- mitochondrial matrix
- inner mitochondrial membrane
• Steps of respiration:
2. Citric acid cycle
3. ETC
4. Chemiosmosis - inner membrane to intermembrane space
Steps of Respiration
Coenzyme Junction
Steps of Respiration
• Stages of respiration:
3. ETC
Proton Motive Force
Substrate-level phosphorylation
Phosphate group moved from substrate to ADP yields ATP
Cellular Respiration
3. Electron transport chain (ETC)
• lots of energy harvested
• released in stages
• so far, 4 ATP – substrate P
• many ATP – oxidative phosphorylationoxidative phosphorylation
Cellular Respiration – mitochondria revisited
Cellular Respiration
• ETC e- collection molecules
• embedded on inner mitochondrial membrane
Electron transport chain (ETC)
• accept e- in turn
• e- ultimately accepted by O2
(O2 reduced to H2O)
~100 H+ (stored)
10 H2O
-outputs:
ATP (none yet)
Where do they go?
H+ build up in intermembrane space (potential energy)
Electron transport chain (ETC)
-inputs: per glucose,
10 NADH
2 FADH2
10 H+
Steps of Respiration
• Stages of respiration:
4. Chemiosmosis
ATP produced!
Cellular Respiration 4. Chemiosmosis
• ATP synthase: inner mitochondrial membrane
• energy input ATP – H+ gradient
• chemiosmosis – ion gradient to do work
Cellular Respiration
• Four parts to ATP synthase:
4. Chemiosmosis
• H+ must enter matrix here
Rotor, Stator, Rod, Knob
• Generates 1 ATP per ~3.4 H+
Cellular RespirationSummary of respiration
• Cells convert ~ 40% of energy in glucose to energy in ATP
• Most fuel efficient cars convert only ~ 25% of gasoline energy
Cellular Respiration - anaerobic
• no O2 – no oxidative phosphorylation
• fermentation
• extension of glycolysis
• substrate-level phosphorylation only
• need to regenerate e- carrier (NAD+)
Cellular Respiration - anaerobic
• Types of fermentation -
1. alcohol
• pyruvate converted to acetaldehyde
• acetaldehyde accepts e-
• ethanol produced
Cellular Respiration - anaerobic
• pyruvate accepts e-
• lactate produced
• Types of fermentation -
2. Lactic acid
Cellular Respiration - anaerobic
• inputs/outputs
• alcohol
• lactic acid
• pyruvate in
• CO2 and EtOH out
• pyruvate in
• lactate out
• brewing & baking
• muscle fatigue
Cellular Respiration
• pyruvate - junction
• O2 present – citric acid cycle
• O2 absent - fermentation
Self-Check
• Comparison of aerobic vs. anaerobic respiration:
• ATP made by:
• ATP per glucose:
Aerobic Anaerobic
• initial e- acceptor:
• final e- acceptor:
Cellular Respiration – other biomolecules
• Glucose catabolism – one option
• Proteins:
• Fats:
Catabolized into a.a.
– Enter diff. points – depends on a.a.
Glycerol in at glycolysis
- becomes pyruvate
Fatty acids in before CAC
- becomes Acetyl CoA
Amino group removed
Self-Check
Step of Respiration
Inputs Outputs CO2/H2O ATP produced
e- carriers loaded
Glycolysis 1 glucose 2 pyruvate 2H2O 2 net 2 NADH
Coenzyme Junction
Citric Acid Cycle
Electron Transport Chain
Oxidative phosphorylation
Fermentation
Lecture 6 concepts- Describe in words the purpose of cellular respiration
- Write the equation for cellular respiration
- Given an equation, particularly that for cellular respiration, determine which molecules are oxidized and reduced
- List the steps of cellular respiration and where they occur
- For glycolysis, coenzyme junction, and the citric acid cycle, give inputs, outputs, ATP made/used, e- carriers loaded, water and carbon dioxide molecules produced
- For the electron transport chain and chemiosmosis, give inputs, outputs, ATP made/used, e- carriers loaded, water and carbon dioxide molecules produced
- Keep track of the total number of carbon molecules going in and coming out for each step of respiration
- Compare substrate-level and oxidative phosphorylation
- Compare the e- carriers, final e- acceptors, and ATP made for aerobic respiration and anaerobic respiration
- Write out a list of new terminology and provide descriptions