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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
Cellular Respiration:
(Exergonic)
• 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
Redox Reactions
• transfer of e- to oxygen is stepwise
Redox Reactions
• e- moved by NAD+ (niacin)
• when “carrying” e- (& H+), NADH
• gained e- (& H+), reduced
Where do e- come from? • food (glucose)
Where do e- go?
• glucose
NADH
ETC
O2 (H2O)
Steps of Respiration
• Steps of respiration:
1. glycolysis
- cytosol
Coenzyme Junction
2. Citric acid cycle
- mitochondrial
matrix
3. ETC
- inner
mitochondrial
membrane
4. Chemiosmosis
- inner membrane to intermembrane space
Cellular Respiration
• Stages of respiration:
1. Glycolysis – prep carbons
Cellular Respiration
1. Glycolysis
• 1 glucose (6C)
2 pyruvate (3C)
• key points: - inputs
- ATP
- NAD+/NADH
- CO2 and H2O
- outputs
• eukaryotes AND prokaryotes
Glycolysis
Cellular Respiration
-inputs: 1 Glucose
2 ATP
-outputs:
2 pyruvate
4 ATP (2 net)
2 NADH
CO2
none
2 H2O
Where do they go?
Cellular Respiration
Coenzyme Junction • 2 pyruvate (3C)
• pyruvate joins coenzyme A (vitamin B)
• 2 C lost (as CO2)
• 2 NAD+  NADH
2 Acetyl CoA (2C)
Steps of Respiration
• Stages of respiration:
2. Citric acid cycle
e- transfer: redox
Cellular Respiration
2. Citric acid cycle
• few ATP so far
• mitochondrial matrix
• 2 Acetyl CoA (2C) join
oxaloacetate (4C)
• 2 citrate (6C)
converted several steps,
4C lost (CO2)
• e- to carriers
(NAD+, FAD)
Citric acid cycle
-inputs: 2 Acetyl CoA (2C)
-outputs:
[2 oxaloacetate (4C)]
2 ATP
6 NADH
2 FADH2
4 CO2
H2O
none
Where do they go?
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
Steps of Respiration
• Steps of respiration:
1. glycolysis
- cytosol
Coenzyme Junction
2. Citric acid cycle
- mitochondrial
matrix
3. ETC
- inner
mitochondrial
membrane
4. Chemiosmosis
- inner membrane to intermembrane space
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 phosphorylation
Cellular Respiration – mitochondria revisited
Cellular Respiration
Electron transport chain (ETC)
• ETC  e- collection molecules
• embedded on inner
mitochondrial membrane
• accept e- in turn
• e- ultimately accepted by O2
(O2 reduced to H2O)
Electron transport chain (ETC)
-inputs: per glucose,
10 NADH
2 FADH2
10 H+
-outputs:
ATP (none yet)
~100 H+ (stored)
10 H2O
Where do they go?
H+ build up in intermembrane space (potential energy)
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
4. Chemiosmosis
• Four parts to ATP synthase:
Rotor, Stator, Rod, Knob
• H+ must enter matrix here
• Generates 1 ATP per ~3.4 H+
Cellular Respiration
Summary 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
• Types of fermentation 2. Lactic acid
• pyruvate
accepts e-
• lactate
produced
Cellular Respiration - anaerobic
• inputs/outputs
• alcohol
• pyruvate in
• CO2 and EtOH out
• brewing & baking
• lactic acid
• pyruvate in
• lactate out
• muscle fatigue
Cellular Respiration
• pyruvate - junction
• O2 present –
citric acid cycle
• O2 absent fermentation
Self-Check
• Comparison of aerobic vs. anaerobic respiration:
Aerobic
• ATP
made by:
• ATP per
glucose:
• initial eacceptor:
• final eacceptor:
Anaerobic
Cellular Respiration – other biomolecules
• Glucose catabolism – one option
• Proteins: Catabolized into a.a.
Amino group removed
– Enter diff. points
– depends on a.a.
• Fats: Glycerol in at glycolysis
- becomes pyruvate
Fatty acids in before CAC
- becomes Acetyl CoA
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