Cellular Respiration

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Cellular Respiration

• Dr. Huq

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Respiration

• Overview
• Glucose to Carbon dioxide Water Energy
• C6H12O6 O2 ? 6CO2 6H2O 38 ATP
• Glucose is highly reduced contains energy
• Oxygen receives the electrons to form energy
• 4 separate reactions
• Glycolysis, Transition Reaction, Krebs Cycle,
  Electron Transport, Chemiosomosis
• Requires Oxygen

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Cellular Respiration By cellular respiration
the pyruvic acid molecules are broken down
completely to form three carbon dioxide
molecules, and three molecules of water. In
glycolysis, a total of four molecules of ATP are
produced, but two are used up in other steps in
the process. Additional ATP is produced during
the Krebs Cycle and the Electron Transport Chain,
resulting in a grand total of 40 ATP molecules
produced from the breakdown of one molecule of
glucose via cellular respiration.
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Cellular Respiration Steps There are
three steps in the process of cellular
respiration glycolysis, the Krebs cycle, and the
electron transport chain.
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Glycolysis- 10 steps

• Glucose is Phosphorylated to form Fructose
  1,6-diphosphate
• Split to form 2 Glyceraldehyde 3-phosphate
• Final Products are
• 2 Pyruvic Acid (C3H4O3)
• Compare to original glucose - C6H12O6
• 2 NADH
• 2 ATP

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Glycolysis There are two important ways a cell
can harvest energy from food fermentation and
cellular respiration. Both start with the same
first step the process of glycolysis which is
the breakdown or splitting of glucose (6 carbons)
into two 3-carbon molecules called pyruvic acid.
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• Glycolysis
• Glycolysis happens in the cytoplasm of cells, not
  in some specialized organelle.
• Glycolysis is the one metabolic pathway found in
  all living organisms.
• Glycolysis does not need oxygen as part of any of
  its chemical reactions. It serves as a first step
  in a variety of both aerobic and anaerobic
  energy-harvesting reactions.

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Krebs Cycle

• Figure E.3, A29
• Acetyl CoA ? Carbon Dioxide
• C2H4O2 to CO2
• Energy produced/Acetyl CoA (x2 for /Glucose)
• 3 NADH
• 1 FADH
• 1 ATP
• Metabolic Wheel
• Fats, amino acids, etc. enter or leave
• Citrate is product of first reaction
• Simmons Citrate Media

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In eukaryotes, the Krebs Cycle and Electron
Transport Chain occur within the
mitochondria. The pyruvic acid resulting from
glycolysis is sent into the mitochondria for
these reactions to occur. To move one molecule
of pyruvic acid from the cytoplasm into a
mitochondrion costs the cell one molecule of
ATP (therefore two ATPs for a whole glucose),
thus a net total of 36 ATP molecules per molecule
of glucose is produced in eukaryotes as compared
to only two in fermentation. The overall
reaction for cellular respiration is
C6H12O6  6O2        6CO2  6H2O (
energy for the cell to use for other things).
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Krebs cycle
In this cycle, discovered by Hans Krebs, the
pyruvic acid molecules are converted to CO2, and
two more ATP molecules are produced per molecule
of glucose. First, each 3-carbon pyruvic acid
molecule has a CO2 broken off and the other two
carbons are transferred to a molecule called
acetyl coenzyme A, while a molecule of NADH is
formed from NAD for each pyruvic acid ( 2 for
the whole glucose). These acetyl CoA molecules
are put into the actual cycle, and after the
coenzyme A part is released, eventually each
2-carbon piece is broken apart into two molecules
of CO2. In the process, for each acetyl CoA that
goes into the cycle, three molecules of NADH, one
molecule of FADH2, and one molecule of ATP are
formed ( 6 NADH, 2 FADH2, and 2 ATP per whole
glucose).
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Fermentation Products from Pyruvate

• Homolactic Lactic Acid
• Yogurt, Lactobacillus
• Alcohol CO2
• Propionic Acid
• Butyric Acid
• Acetic Acid
• Succinic Acid
• Butylene to Acetoin
• basis for VP Test (Vogues-Proskauer)

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Fermentation Lactic acid fermentation is done
by some fungi, some bacteria, in yogurt, and
sometimes by our muscles. Under greater exertion
when the oxygen supplied by the lungs and blood
system cant get there fast enough to keep up
with the muscles needs, our muscles can switch
over and do lactic acid fermentation. In the
process of lactic acid fermentation, the 3-carbon
pyruvic acid molecules are turned into lactic
acid.
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Fermentation Products

• Alcohol and Carbon Dioxide
• Yeast mostly
• Lactic Acid
• Humans, muscles without oxygen
• Bacteria (Lactobacillus-yogurt)
• Butyric Acid
• Rancid butter, Clostridium-gangrene
• Acetoin
• Butanediol fermentation in Klebsiella
• Propionic Acid
• Swiss Cheese

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Fermentation
In fermentation pyruvic acid molecules are turned
into some waste product, only two ATP molecules
per molecule of glucose against four are
produced in glycolysis. two of the most common
types are lactic acid fermentation and alcohol
fermentation.

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Fermentation Alcohol fermentation is done by
yeast and some kinds of bacteria. The waste
products of this process are ethanol and carbon
dioxide (CO2). Humans have long taken advantage
of this process in making bread, beer, and wine.
In bread making, it is the CO2 that causes the
bread to rise.
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Transition Reaction

• Pyruvic Acid ? Acetyl - Co A CO2 NADH
• C2H4O2

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The electron transport chain is a system of
electron carriers embedded into the inner
membrane of a mitochondrion. As electrons are
passed from one compound to the next in the
chain, their energy is harvested and stored by
forming ATP. For each molecule of NADH which puts
its two electrons in, approximately three
molecules of ATP are formed, and for each
molecule of FADH2, about two molecules of ATP are
formed.
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At the last step in the electron transport chain,
the used up electrons, along with some spare
hydrogen ions are combined with O2 (we finally
got around to the O2) to form water as a waste
product 4e-  4H  O2      2H2O.
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Summary of Respiration

• Aerobic Respiration
• Glycolysis
• Transition Rx.
• Krebs Cycle
• Electron Transport Chain
• Anaerobic Respiration
• Pyruvate ?
• Lactic Acid
• Mixed Acids
• Alcohol CO2
• Recycle NADH
• 2 ATP / Glucose

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