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Cell Respiration
What is Cell Respiration?
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Its related to the respiratory system in
that the lungs bring in the oxygen needed
for cell respiration
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Oxygen goes in
Carbon dioxide goes out
How does the Oxygen change to
CO2 ??
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Process happens at cellular level
In the alveoli of the lungs, O2 is
exchanged for CO2 into the
capillaries by diffusion
The circulatory system brings the
oxygen to the cells
In the capillaries, O2 diffuses into
cells and CO2 diffuses out
The circulatory system also brings
Sugar (glucose) to the cells
So sugar and oxygen are delivered to cells
Cellular Respiration
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The complex process of cells
“burning” sugar (glucose) with
oxygen to form usable energy (ATP)
There are 2 types of cell respiration
Aerobic – Occurs in presence of oxygen
Anaerobic – Occurs without oxygen
Aerobic cell respiration
The “Usual” process of respiration
Aerobic means “air”
Occurs with oxygen
Produces up to 38 ATP per glucose
Anaerobic respiration
Occurs without oxygen
Produces only 2 ATP per glucose
Fermentation is anaerobic
Fermentation
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Yeast and some bacteria obtain energy
through anaerobic respiration
Fermentation forms Alcohol, Vinegar or
Lactic acid
Bacteria can only use fermentation
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Prokaryotes have NO Membrane
organelles  No mitochondria
Lactic acid can form from over
exercise or lack of training
Not enough oxygen can cause painful
lactic acid build up in muscles
In Eukaryotic cells, Aerobic
respiration occurs in the mitochondria
Respiration Reaction:
Sugar + O2  CO2 + H20+ Energy (ATP)
(glucose)
Respiration is the opposite of
Photosynthesis
Photosynthesis
In Chloroplasts
CO2 + H2O + SUN  Sugar + O2
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Respiration
In Mitochondria
Sugar + O2
 CO2 + H2O + ATP
Respiration occurs in both
plants and animals
3 Stages of Cell Respiration:
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1) Glycolysis
2) Krebs cycle
3) Electron transport chain
1) Glycolysis
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Occurs in the cytoplasm
Glucose breaks into 2 pyruvates and
forms 2 ATP.
C-C-C-C-C-C  C-C-C + C-C-C + 2 ATP
ATP synthesis by
Substrate level
phosphorylation
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Glycolysis uses
2 ATP to gain 4ATP
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- 2ATP
+ 4ATP
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Net 2 ATP
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Substrate level Phosphorylation
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ATP phosphorylated (phosphate added) by
substrate PEP
2 NADH also
produced in Glycolysis
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NAD+ is reduced with eand gains a H+
e
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NAD+ + H+
NADH
It can be oxidized later
into ATP in ETC
Energy overview glycolysis
Each Pyruvate must become
Acetyl CoA to enter Krebs cycle
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Each pyruvate forms 1 NADH = 2 per
glucose
2) Krebs Cycle
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Also called Citric acid cycle
Occurs in the Mitochondria
Pyruvate is broken into C02 molecules
Energy molecules form
(2 ATP, 6 NADH and 2 FADH2 )
2 C-C-C + O2 6 CO2 + 2 ATP +
6 NADH + 2 FADH2
Each Acetyl CoA enters Krebs
separately. Adds 2 carbons to a 4
carbon (oxaloacetate)
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Acetyl CoA + Oxaloacetate  Citrate + CoA
Products of One Krebs Cycle
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2 C02
3 NADH
1 ATP (substrate level
Phos.)
1 FADH2
Products from 1 glucose molecule
Each Acetyl CoA must go
around cycle
Two turns per glucose
molecule
TOTALS From 1 glucose
 4 C02
 6 NADH
 2 ATP (substrate level
Phos.)
 2 FADH2
3) Electron Transport Chain
(system)
Occurs in the inner
Mitochondria membrane
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NADH and FADH2 are Oxidized
(lose electrons) to form 34 ATP
Oxygen is used up (final electron acceptor)
Water is produced from H+ and OH-
ETC molecules :
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Energy molecules NADH and FADH2 carry
H+ and e- to Inner Mito. membrane where
there are a lot of protein complexes
ETC electron flow
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Electrons flow along protein chain in inner
membrane
At End, Oxygen accepts electrons forming
water
1st - NADH and FADH2 are oxidized
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Electrons are removed from them
releasing energy which is used to pump
H+ into the inner membrane space
Later -Oxygen is the final acceptor of
these electrons which will produce water
2nd - Protons pumped out across
membrane
Proton pump sets up gradient by
chemiosmosis
Chemiosmosis
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is the diffusion of ions across a selectivelypermeable membrane. More specifically, it
relates to the generation of ATP by the
movement of hydrogen ions across a
membrane during cellular respiration.
3rd - ATP formed by Oxidative
phosphorylation in electron
transport chain
ATP synthase phosphorylates using proton
gradient pump in inner mitochondrial
membrane
 OXIDATION
NOT substrate level
phoshorylation
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4th - Oxygen
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At end of ATP phosphorylation, Oxygen
accepts the electrons from the ETC and
combines with the H+ ions and forms
water as a by product of respiration
ATP amounts
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NADH – forms 3 ATP each
FADH2 – forms 2 ATP each
Note – NADH produced in cytosol must
use one ATP to transport into
mitochondria
ATP calculation
Why is second chart different?
Animation ETC
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Electron transport
http://vcell.ndsu.edu/animations/etc/movie-flash.htm
ATP synthase
http://vcell.ndsu.edu/animations/atpgradient/movieflash.htm
QUIZ
What are the 3 stages of cell respiration?
1) Glycolysis
Purpose – Split glucose into pyruvate, form 2 ATP
2) Krebs Cycle
Purpose – Form CO2, form NADH, FADH +ATP
3) Electron transport chain
Purpose – Use NADH + FADH2
to form ATP + H2O