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CELLULAR RESPIRATION
Glucose + Oxygen  Carbon Dioxide + Water (+38 ATP)
VIDEO: CRASHCOURSE RESPIRATION SUMMARY
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RESPIRATION is a process in which organic molecules act as fuel
They are broken down in stages to release chemical potential energy which is used to make ATP
The main fuel for most cells is a carbohydrate, usually glucose
The 3 main processes are:
1 – GLYCOLYSIS
2 – KREBS CYCLE
3 – OXIDATIVE PHOSPHORYLATION (The electron transport chain)
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The overall conversion is:
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enzymes
GLUCOSE + OXYGEN  CARBON DIOXIDE + WATER
(+38 ATP)
or
C6H12O6 + 6O2  6CO2 + 6H20 (+38 ATP)
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GLYCOLYSIS (2 ATP) KREBS CYCLE (2 ATP) OXIDATIVE PHOSPHORYLATION (34 ATP)
36 net gain as 2 ATP used right at the beginning
#NOTE: These figures vary slightly depending on the text being used!!!
Cellular Respiration Overview
Hydrolysis
• Catabolic
Reaction
A.T.P – ADENOSINE
TRIPHOSPHATE
•
ATP  ADP + Pi
ATP can be broken down into ADP and
inorganic phosphate to release energy to
drive other chemical reactions
•
ADP + Pi  ATP
ADP and inorganic phosphate can be
joined to create ATP. This stores energy
and allows it to be transported around the
cell
To make 1 ATP requires 30.7KJ to be stored in
the last bond
• Any reactions that produce less than 30.7KJ can’t
store the energy which is then lost as HEAT
• Any reactions that produce more than 30.7KJ
have the excess released as HEAT
• HELPS KEEP US WARM + WHY ENERGY IS LOST
OUT OF FOOD WEBS
•
Rephosphorylation
• Anabolic
Reaction
GLYCOLYSIS
LOCATION: CYTOPLASM
GLUCOSE  2 x PYRUVATE + 2 ATP + 2 NADH
GLYCOLYSIS: USES 2ATP – MAKES 4ATP – NET GAIN 2ATP
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Glycolysis is the splitting of GLUCOSE (6C) to produce 2 x
PYRUVATE (3C) molecules
The 6C glucose is phosphorylated then split into 2 triose
phosphate molecules (3C) which are then oxidised further
to produce the pyruvate, some ATP and reduced NAD
NAD can be reduced to NADH
- it accepts H+ and transports ions around the cell
- the hydrogen can be transferred easily to other
molecules
Glycolysis is the only part of respiration that USES energy
Glycolysis consists of a series of 10 chemical reactions,
each controlled by its own enzyme
Pyruvate are sent to the mitochondria to be converted via
KREBS CYCLE
The released Hydrogen is carried away by NAD to be used
elsewhere
Glycolysis DOES NOT require oxygen
GLYCOLYSIS
KREBS CYCLE
LOCATION:
TRANSITION – MITOCHONDRIAL MEMBRANE
KREBS CYCLE – MITOCHONDRIAL MATRIX
PYRUVATE  2CO2 + 1FADH + 3NADH + 1ATP
*remember 2 Pyruvates from each glucose
TRANSITION
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Pyruvate passes by active transport from the
cytoplasm, through the outer and inner membranes
of a mitochondria and into the mitochondrial matrix
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Pyruvate is DECARBOXYLATED (Carbon’s lost to form
CO2) – this requires O2 hence it is AEROBIC
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A 2C compound forms – ACETYL CO ENZYME A
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NAD is reduced to form Acetyl Co A x 2 which then
enters Krebs Cycle
Transition Reaction &
KREBS CYCLE
KREBS CYCLE
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Acetyl CoA joins a 4C to form 6C CITRATE
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Citrate is decarboxylated and dehydrogenated
(releases CO2, NAD is reduced)
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A series of steps results back in 4C oxaloacetate
- this then combines with Acetyl CoA and the
process can start again
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Glycolysis produces 2 pyruvate molecules from a
glucose molecule
Each glucose molecule need s 2 cycles to be
completely processed
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Therefore 1 glucose = 2 x 3NADH (6 NADH)
2 x FADH (2 FADH)
2 x ATP
(2 ATP)
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The most important contribution of Krebs
Cycle is the release of H+ to be used in
oxidative phosphorylation
Transition Reaction &
KREBS CYCLE
OXIDATIVE PHOSPHORYLATION
and the ELECTRON TRANSPORT
CHAIN
LOCATION: INNER MITOCHONDRIAL
MEMBRANE
NADH + FADH 
ATP (2 x 17)
electron acceptors
The reduced NAD and FAD from
Krebs Cycle donate the H+ (electrons)
to a series of hydrogen/electron
carriers on the CRISTAE MEMBRANES
•
The electrons are passed from one
electron carrier to the next, losing
energy as they go
•
•The
hydrogen ions pass through the
protein channels on the membrane
- creates a CHEMIOSTATIC gradient
- the H+ ions returning across the
membrane activate
ATP SYNTHASE
- 3 ATP for each NADH
- 2 ATP for each FADH
OXIDATIVE PHOSPHORYLATION
and the ELECTRON TRANSPORT
CHAIN cont......
• Then Oxygen is
used as the FINAL
ELECTRON ACCEPTOR
- the H+ ions combine with the
oxygen to form water
2H+ + ½ O2 + 2e-  H2O
Oxygen is crucial and the electron
transport chain cant work without it
- it helps create a
concentration
gradient by taking away H+
•
•
VIDEO: MINDBITES
ELECTRON TRANSPORT
CHAIN
1 NADH (from Glycolysis) = 3 ATP
3 NADH (from Krebs) = 9 ATP
1 FADH (from Krebs) = 2 ATP
1 NADH (from Transition) = 3 ATP
Total = 17 ATP per Pyruvate
therefore
34 ATP PER GLUCOSE
CELLULAR RESPIRATION – Where it all occurs
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Cellular Respiration generally requires oxygen (for the removal of CO2 and as the last H+
acceptor during the electron transport chain)
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Aerobic Respiration generates A LOT OF ENERGY (36 ATP)
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Anaerobic Respiration is the partial breakdown of glucose to obtain energy WITHOUT OXYGEN
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It occurs in the cytoplasm of the cell
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The products of anaerobic respiration (ethanol & lactic acid) are toxic
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The reactions cant carry on indefinitely and do not produce a large amount of energy
VIDEO: BOZEMAN
ANAEROBIC RESPIRATION
SUMMARY
ANAEROBIC RESPIRATION
The Ethanol Pathway In
Yeast
Alcoholic fermentation:
SUGAR  ETHANOL + CO2 + ENERGY
Anaerobic Respiration
The Lactate Pathway In
Mammals
• Anaerobic respiration in muscle cells that
produces lactic acid
• Lactic Acid causes burning and tiring of muscles
during strenuous exercise
• Lactic Acid is transported to the liver via the
blood
 converted into pyruvate requiring oxygen
 the O2 required is called OXYGEN DEBT