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Cellular Respiration
KEY WORDS:
Oxidation
Reduction
NAD/ NADH
FAD/ FADH2
Cellular respiration
Glycolysis
Kreb’s cycle
Electron transport chain
ATP synthase
Food is used to energize ATP
Electrons transfer energy to
Energize ATP
REDOX REACTIONS
Oxidation = Losing electrons
Reduction = Gaining electrons
TIP: OIL RIG
Gradual transfer of electrons provides most energy (ATP) from food
Main Players: Making ATP
Food
used to make ATP and NADH & FADH2
Electrons
provide energy to pump H+ across
inner mitochondrial membrane
NAD+/H
FAD/H2
carry electrons
carry electrons
H+
provide energy for synthesis of ATP
O2
final electron acceptor in ETC
Cytosol
Mitochondria
location of glycolysis
location of Kreb’s cycle & ETC
ATP Synthase
brings together ADP and P to make ATP
Obtaining Energy from Food
C6H12O6 + 6O2
6CO2 + 6H2O + Energy
• Organisms extract energy
from food over several steps
in small “bite sized” pieces
6CO2+6H2O
C6H12O6+ 6O2
Energy
Energy
Energy
ATP
Cellular
Respiration
Occurs in 3
stages:
1.Glycolysis
2.Kreb’s cycle
3.ETC
1. Glycolysis
•Takes place in the cytoplasm
NAD+
A closer look at glycolysis: energy investment phase (Layer 1)
Good News!
You don’t need to know the
steps of glycolysis!
You need to know what
goes in and what comes out
But here are the steps,
FYI…
A closer look at glycolysis: energy investment phase (Layer 2)
A closer look at glycolysis: energy payoff phase (Layer 3)
A closer look at glycolysis: energy payoff phase (Layer 4)
What’s Happened so far?
Glycolysis
glucose
Glycolysis
Glucose C
O2
ATP NAD
now Product:
H
Used
#
?
#
What’s Happened so far?
Glycolysis
glucose
Glycolysis
O2
Used
?
No
Glucose C
now Product:
Pyruvate
pyruvate
pyruvate
ATP NADH
#
#
2
2
Electron carriers
Some energy captured as electrons
•Energy in food in form of high energy electrons
•Electrons captured when food is broken down
•Held by electron carriers
•NADH, FADH
NAD+ as an electron shuttle
Pyruvate as a key juncture in catabolism
After Glycolysis
•Pyruvic Acid shipped into mitochondria
•One carbon is removed as CO2
•Attach Coenzyme-A  Acetyl-Co-A
•Make one NADH
for each pyruvic
acid
2. Krebs Cycle
•Remaining two carbons removed as CO2
•For each Acetyl-Co-A:
Make
•1 ATP
•3 NADH
•1 FADH2
A closer look at the Krebs cycle (Layer 1)
A closer look at the Krebs cycle (Layer 2)
A closer look at the Krebs cycle (Layer 3)
A closer look at the Krebs cycle (Layer 4)
This is what you need to know
What’s Happened so far?
Krebs Cycle
ATP
NADH
glucose
Original C of
glucose are
now
Glycolysis
2 pyruvate
2
2
Acetyl CoA
formation
2 CO2
& 2 acetyl
CoA
Krebs Cycle
Total
2
FADH2
What’s Happened so far?
Krebs Cycle
ATP
NADH
glucose
Original C of
glucose are
now
Glycolysis
2 pyruvate
2
2
Acetyl CoA
formation
2 CO2
& 2 acetyl
CoA
4 more CO2
6 CO2
Krebs Cycle
Total
FADH2
2
2
6
2
4
10
2
3. Electron Transport Chain (ETC)
•Electrons are passed between several molecules
•Electrons give up energy as passed along
What is oxygen for?
Receives electrons at the end of the
ETC
With H+, forms water
ATP synthase
•Large concentration gradient of H+ builds up
across the mitochondrial membrane
•Works like hydro-electric dam
*H+ is pumped against its gradient
into the mitochondrial matrix.
*Energy for active transport comes
from electrons
Harnessing energy in small steps allows the cell to get
more energy that can be used to do work
Free energy of electrons
decreases as they are
passed through the ETC
Chemiosmosis couples the electron transport chain to ATP synthesis
ATP synthase, a molecular mill
You need energy to think, to keep your heart beating, to play
a sport, and to study this book. This energy is directly
supplied by _____, which is (are) produced in the process of
cellular respiration.
1.
2.
3.
4.
5.
Enzymes
ATP
NAD+
vitamins
proteins
Energy transfer in living things works through redox
reactions, in which one substance is _____ by another
substance, thereby _____.
1.
2.
3.
4.
5.
transported ... becoming more energetic
digested ... becoming more energetic
reduced ... losing electrons to it
oxidized ... losing electrons to it
oxidized ... gaining electrons from it
_____ and _____ are important not so much for the ATP
produced in them, but for their _____.
1. glycolysis ... the Krebs cycle ... yield of electrons
transported to the ETC
2. glycolysis ... the ETC ... yield of electrons transported
to the cytosol
3. Redox reactions ... fatty acid breakdown ... yield of
calories
4. The Krebs cycle ... the ETC ... numerous redox
reactions
5. The Krebs cycle ... the ETC ... fatty-acid breakdown
At most, how many molecules of ATP can be produced per
glucose molecule in cellular respiration?
1.
2.
3.
4.
5.
2
8
24
36
75
We need to breathe because we need
1. both atmospheric nitrogen and the oxygen for energy
transformation
2. oxygen to donate electrons to
3. nitrogen to donate phosphate groups to oxygen
4. oxygen to act as the final acceptor of electrons in the
ETC
5. oxygen to donate phosphate groups to ADP, making it
ATP
Anaerobic Respiration
Fermentation
•live off glycolysis alone
Alcoholic Fermentation
Pyruvate + NADH
Ethanol + CO2 + NAD+
Vinegar
Lactic Acid
Fermentation
Pyruvate + NADH
Lactic Acid + NAD+
Fermentation allows the cycle of glycolysis to continue by regenerating NAD+
Fermentation
An overview of cellular respiration (Layer 1)
An overview of cellular respiration (Layer 2)
Substrate-level phosphorylation
An overview of cellular respiration (Layer 3)
Max of 36 ATP per Glucose
What is all of the ATP used for?