cellular respiration chapter 3 where did bruce lee get all that energy from?
TRANSCRIPT
Cellular Respiration
Chapter 3
Where did Bruce Lee get all that energy
from?
What is it?
• Cellular respiration– An aerobic process (requires oxygen)
– Uses chemical energy from glucose to make ATP
– Chemical energy is now stored in ATP for use throughout the body
O2
ATP36
glucose1Cellular resp.
Four Main Stages
1. Glycolysis• Anaerobic• In cytosol• breaks glucose (6C) into 2 pyruvate molecules
(3C)• releases ATP
2. Transition reaction (oxidative decarboxylation)
• Pyruvate converted to acetyl CoA releasing CO2
3. Kreb’s Cycle• Within mitochondrial matrix• Oxidize each acetyl CoA to CO2
• Releases ATP and co-enzymes (NADH, FADH2)
4. Electron Transport Chain• Along the inner mitochondrial membrane• Uses high energy electrons from NADH and
FADH2 to create an electrochemical proton (H+) gradient which powers ATP synthesis
Fermentation
• When oxygen is NOT available, cells can metabolize pyruvate (derived from glucose) by the process of fermentation.
Two Types
(i) alcohol fermentation: pyruvate (3C) converted (reduced) to ethyl alcohol (2C) and CO2; occurs in yeast cells
(ii) lactic acid fermentation: pyruvate(3C) converted (reduced) to lactic acid (3C) in muscle cells
Cellular Respiration
glucose + O2 CO2 + H2O + energy CO2 H2O
H+H+ EnergyO2
glucose
General Formula
This process begins with glucose. Once it enters a cell, the process of glycolysis begins immediately in the cytoplasm where enzymes are waiting.
Glycolysis (I) Overview
• This is the investment period of glycolysis• ATP is USED in order to “activate” glucose• This is accomplish by an enzyme mediated
process called: substrate level phosphorylation» Involving the transfer of a phosphate group
Numbering the Carbons of Glucose
glucose
C
C
C C
C
O
C
• In order to keep track of how glucose is modified and rearranged during glycolysis we number each carbon
1
23
4
5
6
P P P
glucose
C
C
C C
C
O
C
C
C
C C
C
O
C
P P
P
C
C
C
C
OCP C
C
C
C
C
OCP C P
C C CP CCC P
P P PP P
C
C
C C
C
O
CP
glucose
glucose-6-phosphate
fructose-6-phosphate
fructose-1-6-bisphosphate
2 molecules of
PGAL (glyceraldehyde-3-phosphate)
Glycolysis (I)
Glycolysis (I)
glucose
C
C
C C
C
O
C
C
C
C C
C
O
CP
C
C
C
C
OCP C
C
C
C
C
OCP C P
C C CP CCC P
glucose
glucose-6-phosphate
fructose-6-phosphate
fructose-1-6-biphosphate
2 molecules of
PGAL (glyceraldehyde-3-phosphate)
activation
isomerization
activation
cleavage
ADP
ATP
ADP
ATP
Glycolysis (I)
1. Activation: Phosphate from ATP is added to glucose to form glucose-6-phosphate. [substrate-level phosphorylation]
2. Isomerization: Glucose-6-phosphate is rearranged to form fructose-6-phosphate.
3. Activation: A second phosphate from another ATP is added to form fructose-1,6-bisphosphate. [substrate-level phosphorylation]
4. Cleavage: The unstable fructose-1,6-bisphosphate splits into phosphoglyceraldehyde (PGAL) and dihydroxyacetone phosphate (DHAP).
Investme
nt
Glycolysis (II) Overview
• This is the pay-off period of glycolysis• ATP and NADH (a high energy molecule) are
PRODUCED during glycolysis II• By the end of glycolysis II, glucose has been
broken down from 6 carbons to a 3 carbon compound called Pyruvate (pyruvic acid)
Glycolysis (II)
C C CP CCC P
C C CP CCC P
P PC C CP C C C P
NADNADH
NADNADH
Pi Pi
P P PP P
P PC C CP C C C P
PPP PP
C C C
P
CCC
P
P P PP P PPP PP
P P
C C C CCC
PGAL
PGAP
PGA
PEP
Pyruvate
H2
O
HH
H2
O
HH
Glycolysis (II)
C C CP CCC P
C C CP CCC P
P PC C CP C C C P
NADH NADH
P PC C CP C C C P
C C C
P
CCC
P
P P
C C C CCC
PGAL
PGAP
PGA
PEP
Pyruvate
ATP
ATP
ATP
ATP
activation / redox
dephosphorylation
isomerization / dehydration
dephosphorylation
H2
O
HH
H2
O
HH
5. Activation/Redox: Each molecule of PGAL is oxidized by NAD and gains a phosphate to form 1,3-bisphosphoglycerate (PGAP).
6. Phosphorylation: Each PGAP loses a phosphate to ADP resulting in 2 ATP and two 3-phosphoglycerate molecules (3-PGA).[substrate-level phosphorylation]
7. Isomerization: Both 3-PGA molecules are rearranged to form 2-phosphoglycerate (2-PGA).
[note: the text does not distinguish between 3-PGA and 2-PGA, but refers to both as PGA ]
8. Dehydration: Both 2-PGA molecules are oxidized to phosphoenol pyruvate (PEP) by the removal of water.
9. Phosphorylation: Each PEP molecule loses a phosphate to ADP resulting in 2 more ATP and 2 molecules of pyruvate. [substrate-level phosphorylation]
Glycolysis (II)
Pay-off
The Result
Energy in Glycolysis• Used 2 ATP• Made 4 ATP
Net Gain:
4ATP – 2ATP =
And
ATP2NADH2
(high energy molecule)
1 3
5
6
9
Notice: There is no oxygen used in glycolysis.
It is an anaerobic process
Glycolysis: overall reaction
C6H12O6 + 2ADP + 2P + 2NAD+ 2C3H4O3 + 2NADH + 2ATP
glucose (6C) pyruvate (3C)
O2
The Power House!
• In the cytosol, for each glucose molecule consumed, only 2 ATP were produced
• This means that 34 more ATP are made in the mitochondria!
• How do we get in there and what happens inside!?
nucleus
mitochondria
cytosolATP ATP
ATPATP
ATP
ATPATP
ATPATPATP
ATP
ATP
ATP ATP
ATPATP
ATP
ATP
ATP
ATP
ATPATP
ATPATP
ATP
ATP
ATP
ATP
ATP
ATPATP
ATP
ATPATP
ATP
ATP
Inside the Mitochondria
Inside the Mitochondria
• outer membrane: contains transport protein porin, which affects permeability
• inner membrane: contains the phospholipid cardiolipin that makes membrane impermeable to ions, a condition which is required for ATP production
• intermembrane space: fluid-filled area containing enzymes and hydrogen ions
• matrix: location of Kreb’s Cycle
• cristae: folds of the inner membrane where ETC enzymes are found
Transition Reaction
Intermembrane space mitochondrion
C – C – Cpyruvate multi-enzyme
pyruvate dehydrogenase complex
Transition Reaction
mitochondrion
C – C – Cpyruvate
1. Decarboxylation
C – C
CO2
Intermembrane space
Transition Reaction
mitochondrion
2. OxidationC – C
NAD+
C – C
NADH
Intermembrane space
Transition Reaction
mitochondrion
3. Attachment
C – C
CoA
Intermembrane space
Transition Reaction
mitochondrion
3. Attachment
C – C CoA
Acetyl CoA
Intermembrane space
Transition Reaction
A. Decarboxylation (-CO2) of pyruvate leaving a 2C molecule
B. Oxidation by NAD+ forming an acetate molecule.
C. Attachment of coenzyme A forming acetyl coA.
Steps A and B together are referred to as oxidative decarboxylation
Transition Reaction
In the transition reaction, for each molecule of pyruvate:
CO2
1 is released
and
NADH1 is produced
Transition Reaction
Remember: There are 2 pyruvates produced for each glucose. Therefore, for each glucose:
CO2
1 is released
and
NADH1 is produced
CO2
2 are released
and
NADH2 are prodcuedX2
Krebs Cycle
1. Acetyl coA breaks into coenzyme A, which is recycled, and an acetyl group (2C) which joins to oxaloacetate (4C) forming citrate (6C).
2. Citrate (6C) converts to isocitrate (6C).
3. Isocitrate (6C) loses CO2 and is then oxidized by NAD forming alpha-ketoglutarate (5C). [oxidative decarboxylation]
4. Alpha-ketoglutarate (5C) is converted to succinyl-coA (4C) in 3 steps:
(i) loss of CO2
(ii) oxidation by NAD+(iii) attachment of coenzyme A
Krebs Cycle
5. Succinyl coA (4C) is converted to succinate (4C) in the following way:
- coenzyme A breaks off and is recycled; phosphate attaches temporarily to succinate and is then transferred to GDP forming GTP; GTP transfers phosphate to ADP forming ATP (substrate level phosphorylation).
6. Succinate (4C) is oxidized by FAD to form fumarate (4C).
7. Water is added to fumarate (4C) to form malate (4C).
8. Malate (4C) is oxidized by NAD+ to form oxaloacetate, which is regenerated to begin the cycle again.
Krebs Cycle
Transition reaction
Krebs Cycle
Krebs Cycle
In the Krebs Cycle for each molecule of pyruvate:
CO2
2 are released
NADH3and
FADH21ATP1
are produced
Krebs CycleRemember: There are 2 pyruvates produced for each glucose. Therefore, for each glucose:
CO2
2 are released
NADH3and
FADH21ATP1
are prodcued
CO2
4 are released
NADH6and
FADH22ATP2
are produced
X2
The Story So Far
glucose1C – C
– Cpyruvate2 CO2
6
Tracking carbon:
(6C) (3C) (1C)
The Story So FarTracking High Energy Molecules
Metabolic Process ATP Produced High Energy Molecules
Glycolysis
Transition Reaction (x2)(oxidative decarboxylation)
Krebs Cycle (x2)
Total
NADH2ATP2 NADH6 FADH22
ATP2 NADH2 in cytosol
ATP4 NADH10
FADH22
Using the High Energy Molecules
• NADH and FADH2 have gained high energy electrons
• These electrons are donated to electron carrier proteins in the Electron Transport Chain (ETC).
• The energy from these electrons is then used to pump protons (H+) into the intermembrane space of the mitchondria
ATP Synthase
Electron Transport Chain
Electron Carriers:• 1. NADH reductase [protein]• 2. Coenzyme Q [non-protein]• 3. Cytochrome b1 c1
• 4. Cytochrome c• 5. Cytochrome c oxidase
Cristae QC
NADHreductase
Co-enzymeQ
Cytochromeb1c1
Cytochromec
Cytochrome coxidase
[protein]
not part of the ETC
Electron Transport Chain
• To pass electrons along ETC, each carrier is reduced (gains electrons) then oxidized (donates electrons)
• Curious? Where do these electrons come from?Electrons come from hydrogen atoms (H atoms separate into electrons and protons)
Cristae QC
Electron Transport Chain
1) NADH donates a pair of electrons to NADH reductase
2) electrons continue along ETC via sequential oxidations and reductions
Cristae QC
NADH
NAD+
Electron Transport Chain
1) FADH2 donates a pair of electrons to coenzyme Q
2) electrons also continue along ETC
CristaeC
Q
FADH2
Electron Transport Chain
CristaeC
Q
1) FADH2 donates a pair of electrons to coenzyme Q
2) electrons also continue along ETC
For each NADH, 6 H+ are pumped across the mitochondrion inner membrane
Cristae QC
NADH
NAD+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
For each NADH, 6 H+ are pumped across the mitochondrion inner membrane
Oxygen is the final electron acceptor and is converted to H2O
O2
H2
O
H+H+
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
For each FADH2, 4 H+ are pumped across the mitochondrion inner membrane
O2
H2
O
H+H+
FADH2
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
The electrochemical proton gradient(sometimes referred to as the proton motive force)
H+
H+
H+H+
High Proton Concentration
Low Proton Concentration
Gra
die
nt
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
• Using the energy stored in the proton gradient, ATP is generated using oxidative phosphorylation: formation of ATP coupled to oxygen consumption
H+
H+
H+H+
ATP
Using the electrochemial proton gradient to produce ATP from ADP is called chemiosmosis
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
1 ATP is generated for each proton pair flowing through ATP synthase.
H+
H+
H+H+
ATP
NADHPumps
H+H+6
ATPATP
3
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
1 ATP is generated for each proton pair flowing through ATP synthase.
H+
H+
H+H+
ATP
FADH2
PumpsH+
H+4
ATP
2
• ATP synthase works a bit like a water mill
The WHOLE process…
Cristae QC
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
The WHOLE process…
Cristae QC
NADH
NAD+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
O2
H2
O
H+H+
The WHOLE process…
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+H+
ATPATPATP
The WHOLE process…
CristaeC
Q
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+H+
ATPATPATP
The WHOLE process…
Summing up ATPRemember: BEFORE the ETC we had…
Metabolic Process ATP Produced High Energy Molecules
Glycolysis
Transition Reaction (x2)(oxidative decarboxylation)
Krebs Cycle (x2)
Total
NADH2ATP2 NADH6 FADH22
ATP2 NADH2 in cytosol
ATP4 NADH10
FADH22
Summing up ATPIn the Electron Transport Chain
Molecules from High Energy Molecules
ATP produced in ETC
Glycolysis
Transition Reaction (x2)(oxidative decarboxylation)
Krebs Cycle (x2)
Total
NADH2NADH6 FADH22
NADH2 in cytosol
NADH10
FADH22
ATP4ATP6
ATP22 ATP32
Summing up ATPIN TOTAL
Molecules from High Energy Molecules
ATP produced in ETC
Glycolysis
Transition Reaction (x2)(oxidative decarboxylation)
Krebs Cycle (x2)
Total
NADH2NADH6 FADH22
NADH2 in cytosol
NADH10
FADH22
ATP4ATP6
ATP22 ATP32
ATP34
ATP2+ From Glycolysis
ATP2
Summing up ATPIN TOTAL
Molecules from High Energy Molecules
ATP produced in ETC
Glycolysis
Transition Reaction (x2)(oxidative decarboxylation)
Krebs Cycle (x2)
Total
NADH2NADH6 FADH22
NADH2 in cytosol
NADH10
FADH22
ATP4ATP6
ATP22 ATP34
ATP36
ATP2
ATP2
+ From Krebs Cycle ATP2
glucose + oxygen carbon dioxide + water + energy
Overall Reaction
glucose1 CO2
6NAD+1
0 FAD2
NADH10 FADH22
NAD+10 FAD2
O2 H2OH+H+
Catalysts
ATP36
glucose
O2
CO2
Energy
H2OH+H+
glucose + oxygen carbon dioxide + water + energy
Overall Reaction
glucose1 CO2
6NAD+1
0 FAD2
O2 H2OH+H+
ATP36
Phase (location)
Glycolysis (cytosol)
Transition Reaction (mito.)
Kreb’s Cycle (mito.)
ETC (mito.)
some
some