Download Cellular Respiration

Cellular Respiration
Autotrophs and Heterotrophs

Autotrophs – producers



Use simple inorganic compounds to produce complex
organic compounds
Use external source of NRG
Types:

Photoautotrophs
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
Chemoautotrophs

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Carry out photosynthesis
Light as NRG source
Use oxidation of inorganic compounds (H2S, NH4+ compounds
and Fe2+ compounds) as energy
Heterotrophs - consumers
Aerobes and Anaerobes

Aerobes

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Organisms which utilize O2 to oxidize substances in order to
obtain energy
Types:

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
Obligate aerobes (must use O2 at all times) – most animals,
fungi, some bacteria
Facultative aerobes (use O2, but also have anaerobic methods
to produce NRG) – yeast; even some human cells (use of lactic
acid instead)
Anaerobes


Organisms that do not utilize O2 for NRG
Types:

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Obligate anaerobes (O2 is poisonous)
Facultative anaerobes (can be exposed to O2)
Digestion: Breaking
Down
Macromolecules
into Monomers
Glucose is
converted to
pyruvate in the
cytosol. Pyruvate
enters the
mitochondria.
Phosphorylation

Types of Phosphorylation of ATP:

Substrate-level:



Transfer of phosphate group to ADP from a reactive
intermediate
Not coupled with oxidation
Oxidative


Production of ATP coupled with NADH or FADH2
Requires chemiosmosis of H+ ions across the matrix
membrane (for the most part)
Stage 1 of Cellular Respiration: Glycolysis
(no O2 needed!)


Animation
In the cytosol
First step: Glucose gets phosphorylated!

This way it can’t diffuse out of the cell



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Remember: Transport of glucose across the
membrane
PLUS: destabilization of the ether bond!
End product: 2 molecules of pyruvate
Net Reaction:
Glucose + 2 ADP + 2 Pi + 2 NAD+ - 2 pyruvate + 2 ATP + 2 NADH + 2 H+
C6H12O6 + 2 ADP + 2 Pi + 2 NAD+ - 2 C3H3O3- + 2 ATP + 2 NADH + 2 H+
CH2OH
ADP
ATP
O
O
OH
O
OH
OH
OH
OH
CH2OP
CH2OP
OH
hexokinase
OH
OH
OH
glucose
hexose phosphate isomerase
CH2OH
OH
OH
Glucose-6-phosphate
ATP
fructose-6 -phosphate
ADP
phosphofructokinase
NRG yielding rxns
dihydroxy acetone phosphate
CH2OP
C
O
CH2OP
O
OH
CH2OH
aldolase
3-phosphoglycerate
O
ATP
ADP
C
H C OH
CH2OP
OH
glyceraldehyde - phosphate dehydrogenase
O
phosphoglycerate kinase
NADH
O
NAD+
Pi
OH
fructose-1,6-bisphosphate
O
C
H C OH
H
C
H C OH
CH2OP
CH2OP
OP
glyceraldehyde-3-phosphate
, -diphosphoglycerate
1 3
phosphoglycerate mutase
O
O
H2O
C
H C OP
CH2OH
-phosphoglycerate
2
O
C
C
ADP
O
ATP
O
C
OP
pyruvate kinase
enolase
CH2
phosphoenolpyruvate
CH2OP
O
C
O
CH3
pyruvate
Also this!
NADH will be
used to make
later on more
ATP
In Summary: Energy Yielding Rxns
1. glyceralgehyde 3 phosphate + Pi + NAD+
 1,3 diphosphoglycerate + NADH
•
NADH will be used to make more ATP in
mitochondria
2. 1,3 diphosphoglycerate + ADP  3
phosphoglycerate + ATP
3. Phosphoenolpyruvate + ADP  Pyruvate
+ ATP
Net products from Glycolysis
(per glucose)



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2 pyruvate
2 NADH
2 ATP
Total energy = -61.3 kJ
If there’s no O2
Pyruvate   Lactic Acid
If there is O2
Fates of Pyruvate


Depend on organism and conditions
Yeast
 Anaerobic (no oxygen)
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Aerobic

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Pyruvate decarboxylase
Makes alcohol
Makes acetyl CoA --- energy or fat
Others
 Anaerobic
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Makes lactate
Sore muscles
Aerobic

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Oxidative decarboxylation of pyruvate into Acetyl Co A
Acetyl Co A --- energy or fat
The Krebs Cycle (aka TCA cycle)

Pyruvate enters mitochondria and is
converted to acetyl CoA (by acetyl coenzyme
A)

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Note: Major amounts of acetyl CoA are also
produced by the oxidation of fatty acids
Acetyl CoA is completely degraded to CO2
and H2O
Metabolism is dominated by the Kreb’s cycle
Krebs Cycle
Per Glucose
2 full turns:
 2ATP
 8NADH
 4FADH2
Animation