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CELLULAR RESPIRATION
STATIONS
Markley
STATION 1: OVERVIEW
Cellular Respiration
Objectives:
•Summarize how glucose is broken down in the first
stage of cellular respiration.
•Describe how ATP is made in the second stage of
cellular respiration.
•Identify the role of fermentation in the second
stage of cellular respiration.
•Evaluate the importance of oxygen in aerobic
respiration.
Cellular Respiration
• Is a series of reactions
where fats, proteins,
and carbohydrates,
mostly glucose, are
broken down to make
CO2, water, and
energy.
Mitochondria
• Site of cellular respiration
• Inter membrane
– area between outer and inner
membranes
– contains a high H+
concentration- (acidic)
• Matrix
– area inside the inner
membrane
– low concentration of H+ (less
acidic)
• Cristae
– folds in the inner membrane
– allows for greater surface
area
Inter membrane
ATP
• Most of the energy
from cell respiration is
converted into ATP
• ATP is a substance
that powers most cell
activities.
Vocabulary
• Cellular Respiration – the transfer of energy from an
organic compound into ATP
• Fermentation – the breakdown of carbohydrates by
enzymes, bacteria, yeasts, or mold in the absence of
oxygen
• Pyruvate- an ion of a three-carbon organic acid
called pyruvic acid.
STATION 2: GLYCOLYSIS
I. Glycolysis
• Anerobic process of
splitting glucose
• Forms two pyruvic acid
(pyruvate)
• Produces hydrogen ions
and electrons
• Occurs in the cytoplasm
• Net ATP = 2
STATION 3: TCA/ KREBS CYCLE
Aerobic respiration
• A. Breakdown of
pyruvic acid
– Forms acetyl-CoA
II. Citric Acid Cycle (Krebs Cycle)
• Chemical process
that produces more
ATP and releases
additional electrons
(FADH2 and NADH)
• Occurs in the
mitochondria
• Cycle will happen
twice per molecule of
glucose
• Net ATP = 2
STATION 4: Electron Transport ChainSTRUCTURE
Electron Transport Chain
• Groups of redox proteins
– On inner mitochondrial membrane
– Binding sites for NADH and FADH2
•
•
•
•
On matrix side of membrane
Electrons transferred to redox proteins
NADH reoxidized to NAD+
FADH2 reoxidized to FAD
4 Complexes
•
•
proteins in specific order
Transfers 2 electrons in specific order
– Proteins localized in complexes
•
•
Embedded in membrane
Ease of electron transfer
– Electrons ultimately reduce oxygen to water
•
2 H+ + 2 e- + ½ O2 -- H2O
Electron Transport Chain
Complex 1
•
Removes two electrons from NADH and transfers
them to a lipid-soluble carrier, ubiquinone (Q),
which dissolves into the membrane.
•
At the same time, Complex I moves four protons
(H+) across the membrane, producing a proton
gradient.
Complex II - Succinate
•
•
•
Is not a proton pump.
It serves to funnel additional electrons into the
quinone pool (Q) by removing electrons from
succinate and transferring them (via FAD) to Q.
Point of entry for lipids and some out molecules into
the chain.
•
•
•
Complex III
Removes two electrons from QH2 at the QO site
Transfers them to two molecules of cytochrome
c, a water-soluble electron carrier located within
the intermembrane space.
The two other electrons passed across the
protein quinone, which is reduced to quinol.
Complex IV
• Removes four electrons from four molecules of
cytochrome c
• Transfers electrons to molecular oxygen (O2),
producing two molecules of water (H2O).
• At the same time, it moves four protons across the
membrane, producing a proton gradient.
STATION 5: ETC – Pathways and
Function
STATION 6 – ETC – ATP PRODUCTION
Generation of ATP
• Proton gradient is used by the FOF1 ATP
synthase complex to make ATP via oxidative
phosphorylation.
• ATP synthase is sometimes regarded as
complex V of the electron transport chain.
Generation of ATP Part 2
• The FO component of ATP synthase acts as an ion channel for
return of protons back to mitochondrial matrix.
• Proton Gradient (H+) that was created through the moving of
the electron through the ETC is used by the ATP Synthase to
create ATP
• Coupling with oxidative phosphorylation is a key step for ATP
production.
Generation of ATP part 3
• Step 1: H+ (protons) enter into ATP synthase at the F0
end.
• Step 2: F0 end acts like a Ferris or Water Wheel. The
Proton gets on and spins the F0 section which causes
the F1 section to move
• Step 3: The F1 moves once for each of the H+ ions
moving through F0
• Step 4: F1 Moves through the following sequence:
Open – Bind/lock – Close
– Open – ATP released from binding site on the ATP Synthase
Enzyme leaving it open.
– Bind/Lock – ADP and Pi (Inorganic Phosphate) bind to the
binding site and are locked into place
– Close – ATP Synthase f1 portion slams shut forcing the ADP
+ Pi together to make ATP
ATP SYNTHASE
Net ATP Production
• For every glucose molecule
– Glycolysis
– Krebs cycle
– Electron transport chain
= 2 ATP
= 2 ATP
= 34 ATP
– Total yield
= 38 ATP
STATION 7 - FERMENTATION
Anaerobic Respiration
• Occurs when no oxygen is available
• Fermentation
– Anaerobic process of breaking down pyruvic acid
(pyruvate)
– Two types of anaerobic respiration
• Lactic acid fermentation
• Alcoholic fermentation
Lactic Acid Fermentation
• Lactic acid is formed
• Humans ferment lactic
acid in muscles
• Causes muscle
stiffness after
beginning exercise
programs
Alcoholic fermentation
• Formation of alcohol from sugar
• Yeast converts glucose to
pyruvic acid (pyruvate)
• Then converts pyruvic acid
(pyruvate) into ethanol (ethyl
alcohol), a C-2 compound
• Ethanol produced is found in
beer, wine, and other alcoholic
beverages
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