Transcript Cell Respiration and Fermentation PPT

Cellular Respiration and Fermentation
Chapter 7, Sections 5 and 6
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The Cellular isms
Metabolism: is the set of chemical
reactions that occur in living organisms in
order to maintain life.
– These processes allow organisms to grow
and reproduce, maintain their structures,
and respond to their environments.
– Usually divided into two categories.
Catabolism and Anabolism
− Catabolism: breaking down & releasing
energy
− Anabolism: building up & requires energy
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A Metabolic Pathway called Cellular Respiration
Cells harvest energy by breaking bonds
and shifting electrons from one molecule to
another.
– aerobic respiration - final electron acceptor
is oxygen
–
anaerobic respiration - final electron
acceptor is a molecule other than oxygen
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Aerobic Respiration
Occurs in 3 Stages:
1.
Glycolysis
2.
The Kreb’s Cycle
3.
Electron Transport Chain and ATP
Synthase
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Stage One - Glycolysis
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Occurs in the cytoplasm
For each molecule of glucose that passes through
glycolysis, the cell nets 2 ATP molecules and 2
pyruvic acid molecules
NADH carries 2 high energy electrons
2 NADH
Glucose →
2 Pyruvic Acid
2 ATP
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Stage Two – The Kreb’s Cycle
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Occurs in the matrix of the mitochondrion where
the needed enzymes are dissolved
As pyruvic acid diffuses into the mitochondrion,
each 3C molecule loses a molecule of CO2 and is
converted into acetyl coenzyme A, or acetyl CoA
1 NADH
2 NADH
Glucose →
2 Pyruvic Acid
2 Acetyl
CoA
2 ATP
2 CO2
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Stage Two – The Kreb’s Cycle (con’t)
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Acetyl CoA is oxidized in a series of
reactions
Named after biologist Hans Krebs who first
explained the steps in the 1930s
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Stage Two – The Kreb’s Cycle (con’t)
Acetyl
CoA
3 NADH +
1 FADH2
4-carbon Acceptor
6-carbon Molecule
KREB’S
CYCLE
ATP
CO2
5-carbon Molecule
CO2
After 2 cycles, 6 NADH, 2 FADH2, 4 CO2, and 2 ATP molecules
are produced
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Stage Three: The Electron Transport Chain
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NADH molecules carry electrons to the inner
mitochondrial membrane, where they
transfer electrons to a series of membraneassociated proteins (electron carriers).
Eventually the electrons are pulled towards
OXYGEN and combine with hydrogen ions,
forming water
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Stage Three: ATP Synthase Action
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The ATP released in the ETC is used to move H+
ions across the membrane from low to high
concentrations
This stores potential energy (positive side vs
negative side)
ATP synthase is a protein in the membrane that
spins like a mini turbine as H+ ions flow back
across the membrane
The spinning ATP synthase generates 32-34 ATP
molecules from ADP per original glucose molecule
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ATP Synthase
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Adding up the ATP from Cellular Respiration
Mitochondrion
Glycolysis
2
Glucose
Pyruvic
acid
2
AcetylCoA
Krebs
Cycle
Electron
Transport
ATP Synthase
Maximum
ATP per
glucose:
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Harvesting Energy WITHOUT Oxygen
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If oxygen is not available to capture the 2
low energy electrons at the end of the ETC,
the Kreb’s cycle and the ETC will stop
producing ATP
Glycolysis will continue to generate 2 ATP
molcules, 2 NADH, and 2 Pyruvic Acid
molecules
NADH reacts with the pyruvic acid, making
NAD+ available to carry electrons so
glycolysis can continue making ATP
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Two Types of Fermentation
ALCOHOLIC
Pyruvic Acid → CO2 +
ethyl alcohol
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Occurs in yeast
CO2 makes dough rise
and bubbles in beer &
champagne
Ethyl alcohol makes
alcoholic beverages
LACTIC ACID
Pyruvic Acid → Lactic
Acid
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Occurs in muscles
during vigorous
exercise (can feel
“burn”)
Occurs in prokaryotes
used to make cheese,
yogurt, sour cream,
and sauerkraut
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