Cellular
Respiration
Cellular Respiration
The
process in
which cells
turn food into
usable
energy in the
form of ATP.
Cellular Respiration
RELEASES CHEMICAL ENERGY
FROM SUGARS AND OTHER
CARBON-BASED MOLECULES TO
MAKE ATP WHEN OXYGEN IS
PRESENT!!!!
NO OXYGEN – FERMENTATION!!!!
The Purpose of Cellular Respiration
It is to make and break bonds to generate ATP and
electrons.
You end up with ATP, H ions and electrons.
The electrons are sent to the Electron Transport Chain
where they help to make ATP through ATP synthase.
****Hydrogen ions are bonded with oxygen to make
water which is used in photosynthesis.
Cellular Respiration Overview



Transformation of chemical energy in food into
chemical energy cells can use: ATP
These reactions proceed the same way in plants
and animals. Process is called cellular
respiration
Overall Reaction:
–
C6H12O6 + 6O2 → 6CO2 + 6H2O
Overall Equation for Cellular
Respiration
C6H12O6 + 6O2
YIELDS
6CO2 + 6H20 + e- + 36-38ATP’s
What are the Stages of Cellular
Respiration?
Glycolysis
The
Krebs Cycle
The Electron Transport Chain
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Cellular Respiration



Glycolysis – Occurs before Cell. Resp.
Krebs Cycle (Citric Acid Cycle)
Electron Transport Chain (ETC)
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
lactic acid
Overall Reaction
C6H12O6 + 6O2 → 6CO2 + 6H2O + 38 ATP
Overall this is a three stage process
Glycolysis: before cellular respiration

1.
•
•
Occurs in the cytoplasm
Glucose is broken down
Krebs Cycle
2.
•
•
Breaks down pyruvate into CO2
Occurs in mitochondrial matrix
Electron Transport Chain
3.
•
ATP is synthesized - Occurs in mito membrane
Section 9-2
Flowchart
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
+
ATP
Where Does Cellular Respiration
Take Place?
It
actually
takes place in
two parts of
the cell:
Glycolysis occurs
in the Cytoplasm
Krebs Cycle &
ETC Take place in
the Mitochondria
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What Is ATP?
Energy used by all Cells
Adenosine Triphosphate
Organic molecule containing highenergy Phosphate bonds
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ATP for energy
ATP powers cellular work- made in photosynthesis
and cellular respiration
 A cell does three main kinds of work:
 Mechanical work, beating of cilia, contraction of
muscle cells, and movement of
chromosomes(produces heat)
 Transport work, pumping substances across
membranes against the direction of spontaneous
movement
 Chemical work, driving endergonic reactions such
as the synthesis of polymers from monomers
High Energy Electrons and Molecules
Electron Carrier: a molecule that picks up the
electron and uses this energy to break
apart bonds.
Examples of electron carriers: NADP and ATP
NADP captures two electrons of H and
becomes NADPH.
ADP becomes ATP!!!
How Does ATP Work?






So what?
Energy is stored in these bonds.
So?
The breaking of the chemical bond releases the
energy
ATP + H2O→ ADP + P + ENERGY
ATP is made in photosynthesis and
respiration!!!
ATP (adenosine triphosphate) is a a molecule that
carries energy that cells can use.
How Does ATP Work?


The bonds between phosphate groups can be
broken by hydrolysis which produces
energy!!!
ATP has 3 phosphate groups The bond to the
third bond is easily broken. When the third
bond is broken, energy is released. Becomes
ADP – no energy!!
How Do We Get Energy From ATP?
By breaking
the highenergy
bonds
between the
last two
phosphates
in ATP
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What is the Process Called?
HYDROLYSIS (Adding H2O)
H 2O
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How Does That Happen?
An
Enzyme!
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How is ATP Re-Made?
The reverse of the previous
process occurs.
Another Enzyme is
used!
ATP Synthase
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The ADP-ATP Cycle
ATP-ase
ATP
Synthase
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Chemical Structure of ATP
Adenine Base
3 Phosphates
Ribose Sugar
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What Does ATP Do for You?
It supplies YOU with ENERGY!
Copyright Cmassengale
When is ATP Made in the Body?
During a
Process
called
Cellular
Respiration
that takes
place in both
Plants &
Animals
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Glycolysis
 Definition:
The process in which one
molecule of glucose is broken in
half, producing two molecules of
pyruvic acid, a 3-carbon
compound.
Glycolysis
 Glyco
= glucose
Lysis = break down
 LOCATION: Occurs in the cytoplasm
 This stage occurs in BOTH aerobic and
anaerobic respiration
 Occurs
in ALL eukaryotic cells…
Glycolysis- ATP Production
 In
the pathways beginning, 2 ATP
molecules are used up.
 At the end of glycolysis, 4 ATP
molecules are formed.
 NET GAIN- 2 molecules!!!
Glycolysis- NADH Production
 Process
removes 4 high energy e- and
passes them to nicotinamide adenine
dinuclueotide (NAD+), which is an electron
carrier.
 NAD+ turns into NADH while transferring
electrons to other molecules.
Steps of Glycolysis
1.Two ATP molecules are used to energize a
glucose molecule.
2. Glucose is split into 2 3-carbon molecules.
Enzymes rearrange the molecules.
3. Electrons are transferred to NADP. The
carbon molecules are converted to pyruvate
which enters cellular respiration.
Glycolysis





Location= Cytoplasm
NO O2 required
Energy Yield net gain of 2 ATP at the
expense of 2 ATP
6-C glucose  TWO 3-C pyruvates
Free e- and H+ combine with organic ion
carriers called NAD+  NADH + H+
(nicotinamide dinucleotide)Used in ETC.
Hydrogen attached to water.
Glycolysis:
Get a sheet of paper to review the
process of glycolysis.
Video: Glycolysis
Glycolysis:
Figure 9–3 Glycolysis
Step 1
Glucose
2 Pyruvic acid
To the electron
transport chain
Glycolysis Reactants and Products
Reactants
 1 glucose
 Enzymes are needed
 2 ATP are needed to
start
Products
 2 Pyruvates (go to next
step)
 4 ATP (2 are gained)
 2 NADH (go to ETC)
Really 10 steps with 10 different enzymes
involved.
Anaerobic Respiration (without oxygen):
Fermentation
***fermentation does not make ATP for the cell,
it cycles the ATP for glycolysis***
(does not release energy in cell)
Two Main types:
1) Lactic Acid fermentation- converts pyruvic
acid and NADH to lactic acid and NAD+
-muscle cells
2) Alcoholic fermentation- converts pyruvic acid
and NADH to ethyl alcohol, CO2, NAD+
-yeast (air bubbles in bread)
Main Goals of Krebs Cycle
 Transfer
•
•
high energy electrons(NADH and
FADH2) to molecules that can carry them
to the electron transport chain.
Form some ATP molecules.
Takes place in mitochondria
The Krebs Cycle
Section 9-2
Citric Acid
Production
Mitochondrion
Krebs Cycle-
Part A (Citric Acid Production)
 From
glycolysis, the 3carbon molecule (pyruvic
acid/pyruvate) enters the mitochondria
(innermost layer- Matrix)
 3carbon pyruvic acid is broken down into
2carbon (Acetyl-CoA) molecules.
 CO2 and NADH are produced

Hint: anytime the number of carbons are
reduced, CO2 and NADH are produced
 Acetyl-CoA
(2carbon) combines with 4 carbon
compounds forming a 6 carbon molecule
Citric acid.
Krebs Cycle
Part B (Energy Extraction)
 The
6carbon Citric Acid broken down into
5 carbon compound (releasing CO2 &
NADH)
 5 carbon compound broken down into 4
carbon compound (releasing CO2 &
NADH)
 In a series of 4carbon to 4carbon
reactions, ATP, CO2, NADH & FADH2 are
produced

Remember: NADH & FADH2 are electron
carriers that will take the electrons to the
ETC
Kreb Cycle
Krebs Cycle Reactants and Products
Reactants
 2 Acetyl CoA (pyruvic
acid)
 Remember
when you
form a bond energy is
released!! This is the
key!!
Products
2
ATP
 8 NADH (go to ETC)
 2 FADH2 (go to ETC)
 6 CO2 (given off as
waste)
Krebs Cycle
Electron Transport Chain
Section 9-2
Electron Transport
Hydrogen Ion Movement
Channel
Mitochondrion
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Electron Transport Chain
 Chain
of proteins located on inner mitomembrane
 Uses high energy e- from Krebs cycle to
convert ADP to ATP

Takes place in mitochondrial membrane
Electron Transport ChainPart A

High energy e- move from one carrier protein
to the next until an enzyme at the end of
chain combines e- with H+ ions and oxygen
to form water.

Important: Oxygen serves as FINAL e- acceptor
Electron Transport ChainPart B
 When
2e- transport down the chain, they
also transport H+ ions across the
membrane

H+ ions build up in the inter membrane
having a pos. charge leaving the inner
membrane with a neg. charge.
Electron Transport
Chain-Part C
 As
H+ ions build up, they travel back
across membrane through ATP synthase
(protein spheres)
 They cause ATP synthases to spin and
“grab” low energy ADP so a phosphate
can attach to form ATP
Electron Transport Chain
(overview)



Electron carriers loaded with electrons and
protons from the Kreb’s cycle move to this
chain-like a series of steps (staircase).
As electrons drop down stairs, energy
released to form a total of 32 ATP – Final
Goal!!
Oxygen waits at bottom of staircase, picks up
electrons and protons and in doing so
becomes water
Electron Transport Chain
 Where
inner membrane of mitochondria
called cristea.
 Energy Yield Total of 32 ATP
 O2 combines with TWO H+ to form H2O
 Exhale - CO2, H2O comes from cellular
respiration
 Video:
ETC
Section 9-2
Flowchart
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
+
ATP
Energy Tally


36 ATP for aerobic vs. 2 ATP for anaerobic

Glycolysis
2 ATP

Krebs
2 ATP

Electron Transport
32 ATP
36 ATP
Anaerobic organisms can’t be too energetic
but are important for global recycling of
carbon