cell respiration-introduction energy needed to keep the entropy of the cell low importance of atp...
TRANSCRIPT
Cell Respiration-Introduction
• Energy needed to keep the entropy of the cell low
• Importance of ATP
• Autotrophs and heterotrophs-similarities and differences
What can you tell about cell respiration from the equation?
• Balanced Equation for Aerobic Cellular Respiration
• C6H12O6 + (6)O2 (6)CO2 + (6)H2O + energy
• Energy (delta G=(-)140 Kcal/mol)=ATP + heat
2 ways to store energy from exergonic breakdown of glucose
• Reduction of NAD+
• Phosphorylation of ADP
Oxidation/reduction reactions
• Definition of oxidation and reduction
• Electron and hydrogen transfer
• Reduced substances have a higher free energy than their oxidized counterparts
LE 9-UN161
becomes oxidized
becomes reduced
LE 9-UN162a
becomes reduced
becomes oxidized
Coenzymes
• The importance of the coenzymes NAD and FAD in cellular respiration
• Coenzymes can alternate between the oxidized and reduced form (recycling)
• Coenzymes are present in the cell in limited amounts
• Many enzymes (dehydrogenases) in cell respiration require the oxidized coenzyme (without it, they won’t work)
LE 9-4
NAD+
Nicotinamide(oxidized form)
Dehydrogenase
2 e– + 2 H+
2 e– + H+
NADH H+
H+
Nicotinamide(reduced form)
+ 2[H](from food)
+
LE 9-UN162b
Dehydrogenase
ATP synthesis during Cellular Respiration
• Substrate level-phosphorylation
• Oxidative phosphorylation
Substrate-level phosphorylation
• Involves the transfer of a phosphate from one organic molecule to another during an enzyme catalyzed reaction
• Does not require membranes to occur
• Produces a small amount of ATP/glucose in cellular respiration (4 net ATP/glucose out of the 38 possible produced).
LE 9-7
Enzyme
ADP
P
Substrate
Product
Enzyme
ATP+
ATP production by Oxidative Phsophorylation
• Use the energy of an H+ gradient to drive the endergonic reaction of ADP + PATP (chemiosmosis)
• The phophate transferred to ADP is inorganic • Membranes are required (a membrane
separation two compartments)-mitochondria• Occurs when reduced NAD and FAD are
reoxidized (recycled) during cellular respiration • Produces most of the ATP during cell respiration
(34 ATP/glucose out of the maximum 38 possible)
Cellular Respiration is a multistep metabolic pathway
• Why is it many individual steps rather than 1 step?
LE 9-5
2 H+ + 2 e–
2 H
(from food via NADH)
Controlledrelease ofenergy for
synthesis ofATP ATP
ATP
ATP
2 H+
2 e–
H2O
+ 1/2 O21/2 O2H2 +
1/2 O2
H2O
Explosiverelease of
heat and lightenergy
Cellular respirationUncontrolled reaction
Fre
e en
erg
y, G
Fre
e en
erg
y, G
Electro
n tran
spo
rt chain
Aerobic Cellular respiration consists of three linked metabolic sequences
• Glycolysis
• Citric Acid (Kreb’s cycle)
• Electron Transport System
Cellular Respiration• Cell Biology -Respiration-Things you should know about the metabolic
sequences 1) glycolysis 2) Kreb’s cycle (including transition reaction), and 3) the electron transport system
• 1. Starting compound• 2. end product• 3. Is CO2 produced ?• 4. Is NAD+ reduced?• 5. Is NADH oxidized?• 6. Is FAD reduced?• 7. Is FADH2 oxidized?• 8. Cellular location• 9. Is ATP produced by substrate-level phosphorylation? If so, how much
per glucose?• 10. Is ATP produced by oxidative phosphorylation? If so, how much per
glucose?• 11. Is molecular oxygen (O2) directly involved in the sequence?• 12. Is ATP used up during the sequence?
LE 9-6_3
Mitochondrion
Glycolysis
PyruvateGlucose
Cytosol
ATP
Substrate-levelphosphorylation
ATP
Substrate-levelphosphorylation
Citricacidcycle
ATP
Oxidativephosphorylation
Oxidativephosphorylation:electron transport
andchemiosmosis
Electronscarried
via NADH
Electrons carriedvia NADH and
FADH2
LE 9-6_1
Mitochondrion
Glycolysis
PyruvateGlucose
Cytosol
ATP
Substrate-levelphosphorylation
LE 9-8
Energy investment phase
Glucose
2 ATP used2 ADP + 2 P
4 ADP + 4 P 4 ATP formed
2 NAD+ + 4 e– + 4 H+
Energy payoff phase
+ 2 H+2 NADH
2 Pyruvate + 2 H2O
2 Pyruvate + 2 H2O
2 ATP
2 NADH + 2 H+
Glucose
4 ATP formed – 2 ATP used
2 NAD+ + 4 e– + 4 H+
Net
Glycolysis Citricacidcycle
Oxidativephosphorylation
ATPATPATP
LE 9-9a_1
Glucose
ATP
ADP
Hexokinase
ATP ATP ATP
Glycolysis Oxidationphosphorylation
Citricacidcycle
Glucose-6-phosphate
LE 9-9a_2
Glucose
ATP
ADP
Hexokinase
ATP ATP ATP
Glycolysis Oxidationphosphorylation
Citricacidcycle
Glucose-6-phosphate
Phosphoglucoisomerase
Phosphofructokinase
Fructose-6-phosphate
ATP
ADP
Fructose-1, 6-bisphosphate
Aldolase
Isomerase
Dihydroxyacetonephosphate
Glyceraldehyde-3-phosphate
LE 9-9b_1
2 NAD+
Triose phosphatedehydrogenase
+ 2 H+
NADH2
1, 3-Bisphosphoglycerate
2 ADP
2 ATPPhosphoglycerokinase
Phosphoglyceromutase
2-Phosphoglycerate
3-Phosphoglycerate
LE 9-9b_2
2 NAD+
Triose phosphatedehydrogenase
+ 2 H+
NADH2
1, 3-Bisphosphoglycerate
2 ADP
2 ATPPhosphoglycerokinase
Phosphoglyceromutase
2-Phosphoglycerate
3-Phosphoglycerate
2 ADP
2 ATPPyruvate kinase
2 H2OEnolase
Phosphoenolpyruvate
Pyruvate
LE 9-18
Pyruvate
Glucose
CYTOSOL
No O2 presentFermentation
Ethanolor
lactate
Acetyl CoA
MITOCHONDRION
O2 present Cellular respiration
Citricacidcycle
LE 9-17a
CO2
+ 2 H+
2 NADH2 NAD+
2 Acetaldehyde
2 ATP2 ADP + 2 P i
2 Pyruvate
2
2 Ethanol
Alcohol fermentation
Glucose Glycolysis
LE 9-17b
CO2
+ 2 H+
2 NADH2 NAD+
2 ATP2 ADP + 2 P i
2 Pyruvate
2
2 Lactate
Lactic acid fermentation
Glucose Glycolysis
Summary-Fermentation
LE 9-6_3
Mitochondrion
Glycolysis
PyruvateGlucose
Cytosol
ATP
Substrate-levelphosphorylation
ATP
Substrate-levelphosphorylation
Citricacidcycle
ATP
Oxidativephosphorylation
Oxidativephosphorylation:electron transport
andchemiosmosis
Electronscarried
via NADH
Electrons carriedvia NADH and
FADH2
Fermentation:
Recycle
s reduc..
.
Is th
e same as..
.
Only occu
rs in...
Produce
s more
...
All of t
he abo...
20% 20% 20%20%20%1. Recycles reduced NAD back into oxidized NAD
2. Is the same as glycolysis
3. Only occurs in yeast
4. Produces more ATP than glycolysis
5. All of the above
In which metabolic pathway(s) is CO2 produced?
a) glyc
olysis,
b) ferm
entati
on,
c) ci
tric a
cid cy
cle,
d) a and b,
e) b and c)
,
f) a and c,
g) all o
f the ab
ove,
h) none of t
he above
12% 12% 12% 12%12%12%12%12%a) glycolysis,
b) fermentation,
c) citric acid cycle,
d) a and b,
e) b and c),
f) a and c,
g) all of the above,
h) none of the above
In which metabolic pathway(s) ATP produced by substrate-level phosphorylation?
a) glyc
olysis,
b) ferm
entati
on,
c) ci
tric a
cid cy
cle,
d) a and b,
e) b and c)
,
f) a and c,
g) all o
f the ab
ove,
h) none of t
he above
12% 12% 12% 12%12%12%12%12%a) glycolysis,
b) fermentation,
c) citric acid cycle,
d) a and b,
e) b and c),
f) a and c,
g) all of the above,
h) none of the above
LE 9-11Pyruvate(from glycolysis,2 molecules per glucose)
ATP ATP ATP
Glycolysis Oxidationphosphorylation
CitricacidcycleNAD+
NADH
+ H+
CO2
CoA
Acetyl CoACoA
CoA
Citricacidcycle
CO22
3 NAD+
+ 3 H+
NADH3
ATP
ADP + P i
FADH2
FAD
LE 9-10
CYTOSOL
Pyruvate
NAD+
MITOCHONDRION
Transport protein
NADH + H+
Coenzyme ACO2
Acetyl Co A
LE 9-12_1
ATP ATP ATP
Glycolysis Oxidationphosphorylation
Citricacidcycle
Citricacidcycle
Citrate
Isocitrate
Oxaloacetate
Acetyl CoA
H2O
LE 9-12_2
ATP ATP ATP
Glycolysis Oxidationphosphorylation
Citricacidcycle
Citricacidcycle
Citrate
Isocitrate
Oxaloacetate
Acetyl CoA
H2O
CO2
NAD+
NADH
+ H+
-Ketoglutarate
CO2NAD+
NADH
+ H+SuccinylCoA
LE 9-12_3
ATP ATP ATP
Glycolysis Oxidationphosphorylation
Citricacidcycle
Citricacidcycle
Citrate
Isocitrate
Oxaloacetate
Acetyl CoA
H2O
CO2
NAD+
NADH
+ H+
-Ketoglutarate
CO2NAD+
NADH
+ H+SuccinylCoA
Succinate
GTP GDP
ADP
ATP
FAD
FADH2
P i
Fumarate
LE 9-12_4
ATP ATP ATP
Glycolysis Oxidationphosphorylation
Citricacidcycle
Citricacidcycle
Citrate
Isocitrate
Oxaloacetate
Acetyl CoA
H2O
CO2
NAD+
NADH
+ H+
-Ketoglutarate
CO2NAD+
NADH
+ H+SuccinylCoA
Succinate
GTP GDP
ADP
ATP
FAD
FADH2
P i
Fumarate
H2O
Malate
NAD+
NADH
+ H+
Summary-Citric Acid cycle
Why is the citric acid cycle important?
It co
mpletes t
...
It pro
duces a
...
It re
cycle
s ox...
It genera
tes O
...
25% 25%25%25%1. It completes the oxidation of pyruvate
2. It produces a lot of ATP by chemiomosis
3. It recycles oxidized NAD back into reduced NAD
4. It generates O2 that is needed by the ETS
If a cell is deprived of oxygen:
ATP producti
on...
FADH2 w
ill not..
.
The citri
c aci.
..
1 and 2
All of t
he abo...
20% 20% 20%20%20%1. ATP production by oxidative phosphorylation will cease
2. FADH2 will not be recycled
3. The citric acid cycle will stop
4. 1 and 2
5. All of the above
Which of the following is not true about the electron transport system?
It co
nsists
of...
It co
ntains c
y...
It is
found in
...
It has e
lectro...
Some of it
s co...
20% 20% 20%20%20%1. It consists of two types of
molecules, some hydrogen and some electron carriers
2. It contains cytochromes
3. It is found in the mitochondrial matrix
4. It has electron transport system components that are assymetrically distributed within the mitochondrial inner membrane
5. Some of its components are iron containing proteins
If 4 molecules of NADH are recycled by the ETS, how many ATP could be produced at the same
time?
1 4 8 12 16
20% 20% 20%20%20%1. 1
2. 4
3. 8
4. 12
5. 16
The mitochondrial inner membrane:
Is norm
ally im
...
Separate
s the ...
Contains a
cha...
Is th
e loca
tio...
All of t
he abo...
20% 20% 20%20%20%1. Is normally impermeable to
H+
2. Separates the inner membrane space and the matrix in the mitochondria
3. Contains a channel protein which is also an ATPase enzyme
4. Is the location of the electron transport system
5. All of the above
LE 9-13
ATP ATP ATP
GlycolysisOxidative
phosphorylation:electron transportand chemiosmosis
Citricacidcycle
NADH
50
FADH2
40 FMN
Fe•S
I FAD
Fe•S II
IIIQ
Fe•S
Cyt b
30
20
Cyt c
Cyt c1
Cyt a
Cyt a3
IV
10
0
Multiproteincomplexes
Fre
e en
erg
y (G
) re
lati
ve t
o O
2 (k
cal/m
ol)
H2O
O22 H+ + 1/2
LE 9-15
Protein complexof electroncarriers
H+
ATP ATP ATP
GlycolysisOxidative
phosphorylation:electron transportand chemiosmosis
Citricacidcycle
H+
Q
IIII
II
FADFADH2
+ H+NADH NAD+
(carrying electronsfrom food)
Innermitochondrialmembrane
Innermitochondrialmembrane
Mitochondrialmatrix
Intermembranespace
H+
H+
Cyt c
IV
2H+ + 1/2 O2 H2O
ADP +
H+
ATP
ATPsynthase
Electron transport chainElectron transport and pumping of protons (H+),
Which create an H+ gradient across the membrane
P i
ChemiosmosisATP synthesis powered by the flow
of H+ back across the membrane
Oxidative phosphorylation
LE 9-14
INTERMEMBRANE SPACE
H+ H+
H+H+
H+
H+
H+
H+
ATP
MITOCHONDRAL MATRIX
ADP+
Pi
A rotor within the membrane spins as shown when H+ flows past it down the H+ gradient.
A stator anchored in the membrane holds the knob stationary.
A rod (or “stalk”) extending into the knob also spins, activating catalytic sites in the knob.
Three catalytic sites in the stationary knob join inorganic phosphate to ADP to make ATP.
Summary-Electron Transport Sytem
LE 9-16
CYTOSOL Electron shuttlesspan membrane 2 NADH
or
2 FADH2
MITOCHONDRION
Oxidativephosphorylation:electron transport
andchemiosmosis
2 FADH22 NADH 6 NADH
Citricacidcycle
2AcetylCoA
2 NADH
Glycolysis
Glucose2
Pyruvate
+ 2 ATP
by substrate-levelphosphorylation
+ 2 ATP
by substrate-levelphosphorylation
+ about 32 or 34 ATP
by oxidation phosphorylation, dependingon which shuttle transports electronsform NADH in cytosol
About36 or 38 ATPMaximum per glucose:
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cy
top
las
mM
ito
ch
on
dri
on
Ele
ctr
on
tra
ns
po
rt c
ha
in
2net
2
glucose
subtotal subtotal
2 CO2
4 CO2
FADH2
2
2
6
2
4 or 6
6
18
4
324
6 O2
ATP
or 34
ATP
ATP
ATP
ATPATP
ATP
ATP
ATP
2 pyruvate
2 acetyl CoA
Citric acidcycle
NADH + H+
NADH + H+
NADH + H+
glycolysis
6 H2O
36 or 38total
Summary-Energy Yield-Aerobic Cellular Respiration
LE 9-19
Citricacidcycle
Oxidativephosphorylation
Proteins
NH3
Aminoacids
Sugars
Carbohydrates
Glycolysis
Glucose
Glyceraldehyde-3- P
Pyruvate
Acetyl CoA
Fattyacids
Glycerol
Fats
LE 9-20
Citricacidcycle
Oxidativephosphorylation
Glycolysis
Glucose
Pyruvate
Acetyl CoA
Fructose-6-phosphate
Phosphofructokinase
Fructose-1,6-bisphosphate
–
Inhibits
ATP Citrate
Inhibits
Stimulates
AMP
+
–
Overall Summary-Cell Respiration