Transcript CELLULAR RESPIRATION

CELLULAR RESPIRATION
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The process by which mitochondria break
down food molecules to produce ATP.
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Occurs in all living organisms EXCEPT for
bacteria.
3 stages of cellular respiration

1.) glycolysis-anaerobic
2.) the citric acid cycle/Krebs
cycle-aerobic
 3.) the electron transport chain-aerobic
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GLYCOLYSIS
Does not need oxygen
 Occurs in the cytoplasm of the cell
 Breaks down glucose (a 6 carbon
compound) into 2 molecules of pyruvic
acid (a 3 carbon compound)
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A net amount of 2 ATPs are produced
 Not very efficient
 Bacteria use this stage only
 2 NADH molecules are formed and move
to the electron transport chain
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NADH
An important component of cellular
respiration is that electrons are stripped off
of the original glucose molecule.
 These electrons need to be shuttled over
to the e.t.c.
 When NAD+ picks up electrons and a
hydrogen, it becomes NADH
 NADH delivers the electrons to the etc
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INTO THE MITOCHONDRIA
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After glycolysis, pyruvic acid molecules move
into the mitochondria.
First, pyruvic acid gives off a CO2 molecule, an
NADH is formed and a 2 carbon molecule
combines with coenzyme A to form a new
molecule called acetyl-CoA
THE CITRIC ACID CYCLE
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AKA the Krebs cycle
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Molecule used at the beginning is also the
end product
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For each cycle, 1 ATP, 2 CO2, 3 NADH,
and 1 FADH2 molecules are made.
http://vcell.ndsu.nodak.edu/animations/glyc
olysis_overview/movie-flash.htm
The Citric Acid Cycle
The electron transport chain
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In the inner membrane of the mitochondria
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Molecules that are electron carriers take
energized electrons from the Citric acid cycle to
the beginning of the electron transport chain.
Energized electrons move along the inner
membrane of the mitochondria.
 Energy from the moving electrons is used
to generate ATP.

How?
Electrons are moving from one protein
complex to the next
 The moving electrons are used to move
hydrogen ions (H+, protons) from the
matrix to the intermembrane space
 Hydrogen ions flow through the ATP
synthase back into the matrix
 The moving ATP synthase adds Pi to ADP
making LOTS of ATP!
 http://www.science.smith.edu/departments
/Biology/Bio231/etc.html
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The final electron acceptor, at the end of
the chain, is O2.
 When O2 accepts electrons, as well as H+,
it forms H2O.
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In this stage, about 32 ATP molecules are
produced!
http://vcell.ndsu.nodak.edu/animations/etc/i
ndex.htm
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This is why we need oxygen-if there is no
oxygen, the electron transport chain in the
mitochondria stops, ATP is no longer
made, and cells cannot obtain energy.
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Which stage produces the most ATP?
Equation for cellular respiration
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C6H12O6 + 6O2 
6CO2 + 6H2O
FERMENTATION
A method for cells to produce ATP without
oxygen (anaerobic)
 There are 2 types
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Lactic acid fermentation
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Have your muscles ever been sore from
too much exercise?
When exercising, sometimes you cannot
provide enough oxygen to your muscle
cells, so they turn pyruvic acid from
glycolysis into lactic acid to make 2 more
ATP molecules.
 The lactic acid in your muscle cells is what
makes you sore!

Alcoholic fermentation
Used by yeast (kingdom fungi) and some
bacteria to produce CO2 and ethyl alcohol.
 Process used to make bread, beer, and
wine.
 Anaerobic
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Comparing photosynthesis and
cellular respiration
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Similarities:
Use an electron transport chain
 Use a cycle
 Make ATP
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Differences:
Different products
 Occur in different locations
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