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Chapter 8
Cellular Respiration
&
Cellular Energy
1) Uses of Energy
The ability to do work
A) Most energy received by
burning of “fuels”.
B) Energy released can be
converted to other forms.
C) Carbon & Hydrogen combine
with Oxygen to make
Carbon dioxide and Water.
2) Energy from Food
(Carbohydrates)
are the main source
A) Heat released is used to
maintain body temperature.
B) Rest of energy is conserved in
a chemical form.
C) Cell Respiration – the slow
release of food energy.
3) Food Energy is stored in
molecules of ATP
A) Adenine – a base found in
DNA & RNA.
B) Ribose – a 5-carbon sugar
found in RNA.
C) Adenosine – combination of
Adenine + Ribose.
D) Phosphate group – (PO4)
found in DNA & RNA.
E) Cells use similar molecules for
different functions.
F) AMP – Adenosine MonoPhosphate.
G) Energy is stored in High
Energy Phosphate Bonds.
H) Energy is transferred when
phosphates are removed.
I) Phosphorylation – transfer of a
phosphate.
J) ATP ----> ADP + P + energy
4) Sources of energy for ATP
A) Food energy used to add a
Phosphate to ADP.
B) ATP then used for cellular
reactions.
C) Glucose supplies most cell
energy (1Glucose = 36 ATP)
D) Energy is packaged in small,
efficient units (ATP).
Food Energy + Phosphate
ADP
ATP
Phosphate +Energy for cells
5) Oxidation-Reduction reactions
A) Oxidation – Electrons or
Hydrogen atoms removed.
B) Reduction – Electrons or
Hydrogen atoms gained.
C) Redox reactions involve the
transfer of energy.
D) Oxidation of glucose results in
energy release thru the loss
of electrons and hydrogen
atoms.
6) Hydrogen Acceptors – NAD &
FAD
A) Biological reactions involve
Redox reactions.
B) Enzymes require co-enzymes to
accept Hydrogen atoms and
their electrons.
C) NAD – Nicotinamide Adenine
Dinucleotide.
D) FAD – Flavin Adenine
Dinucleotide (Riboflavin).
E) NAD + 2H  NADH2
FAD + 2H  FADH2
F) NADH2 & FADH2 are high
energy molecules.
G) Energy from these are used to
make ATP.
7) Types of Respiration
Aerobic – oxygen required. Glucose is
completely broken down and
maximum amount of energy is
released.
Anaerobic – no oxygen used. Glucose
is partially broken down and a minimal
amount of energy is released.
Phases of respiration: Glycolysis,
Kreb’s Cycle, Electron Transport
System
9-1 Chemical Pathways
Overview of Cellular Respiration
Glycolysis takes place in the cytoplasm.
The Krebs cycle and electron transport take place
in the mitochondria.
Glycolysis
Cytoplasm
Mitochondrion
Slide
9 of 39
Copyright Pearson Prentice Hall
End Show
8) Glycolysis – splitting of glucose
ATP used as activation energy
Glucose splits into 2 PGAL
molecules
PGAL converted into Pyruvic Acid:
2 NADH2 & 2 ATP produced
Net of 2 ATP produced in glycolysis
9) Fermentation
Fermentation is anaerobic
respiration.
Glycolysis is followed by the
conversion of pyruvic acid into
lactic acid in animals & alcohol in
plants.
2 ATP’s and CO2 are produced.
Yeast fermentation used to bake
bread.
10) Kreb’s (Citric Acid) Cycle
Completes the break down of glucose.
Pyruvic Acid enters Mitochondria
Pyruvic Acid converted into Acetic
Acid
2 NADH2 & 2 CO2 produced
Enzymes on Cristae complete rest of
reaction.
All intermediates are recycled each
turn.
Kreb’s cycle produces 4 CO2, 6
NADH2, 2 FADH2 & 2 ATP
11) Electron Transport System
Electron carriers accept hydrogens
from NADH2 & FADH2 and remove
energy.
Energy in hydrogens used to make
ATP.
Each NADH2 produces 3 ATP’s
Each FADH2 produces 2 ATP’s
32 ATP’s total produced by the ETS
Oxygen is the final hydrogen acceptor
to form water in the last step.
Electron Transport
Electron Transport
– The electron transport chain uses the
high-energy electrons from the Krebs
cycle to convert ADP into ATP.
Electron Transport
High-energy electrons from NADH and FADH2
are passed along the electron transport chain
from one carrier protein to the next.
Electron Transport
At the end of the chain, an enzyme combines
these electrons with hydrogen ions and oxygen
to form water.
Electron Transport
As the final electron acceptor of the electron
transport chain, oxygen gets rid of the low-energy
electrons and hydrogen ions.
Electron Transport
When 2 high-energy electrons move down the
electron transport chain, their energy is used to
move hydrogen ions (H+) across the membrane.
Electron Transport
During electron transport, H+ ions build up in the
intermembrane space, so it is positively charged.
Electron Transport
The other side of the membrane, from which those
H+ ions are taken, is now negatively charged.
Electron Transport
The inner membranes of the mitochondria contain
protein spheres called ATP synthases.
ATP
synthase
Electron Transport
As H+ ions escape through channels into these
proteins, the ATP synthase spins.
Channel
ATP
synthase
Electron Transport
As it rotates, the enzyme grabs a low-energy ADP,
attaching a phosphate, forming high-energy ATP.
Channel
ATP
synthase
ATP
Electron Transport
On average, each pair of high-energy
electrons that moves down the electron
transport chain provides enough energy to
produce three molecules of ATP from ADP.