Download Cellular Respiration - Jackson School District

 Complete the warm-ups.
 You can cut these up for your note cards later.
Oxidizing Food Molecules
 Energy: One way flow
 In from sun, Lost as heat
 Biochemicals
constantly recycle
Energy stored in food can be traced back to the
sun
Fuel molecules in food store solar energy in
chemical bonds
Animals depend on plants to convert solar
energy to chemical energy
This chemical energy is in the form of sugars and
other organic molecules
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 Autotrophs - Producers - Plants and other
organisms that make all their own organic
matter from inorganic nutrients
 Heterotrophs – Consumers - Humans and
other animals that cannot make organic
molecules from inorganic ones
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 Both plants and animals perform
cellular respiration
 Cellular respiration is a chemical
process that harvests energy from
organic molecules and occurs in the
mitochondria
 The waste products of cellular
respiration, CO2 and H2O, are used
in photosynthesis
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Citric Acid
Cycle
(matrix)
ETC
(inner membrane)
When you exercise:
 Muscles need energy in order to perform
work
 Your cells use oxygen to release energy from
the sugar - glucose
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Aerobic metabolism
- When enough oxygen
reaches cells to support
energy needs
- Maximum energy
production
Anaerobic metabolism
 When the demand for
oxygen outstrips the
body’s ability to deliver
it
 Low energy production
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 Without enough oxygen, muscle cells break down
glucose to produce lactic acid
 Lactic acid is associated with the “burn”
accompanying heavy exercise
 If too much lactic acid builds up, your muscles
give out
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 Allows your body to adapt to
increased activity
 The body can increase its
ability to deliver oxygen to
muscles
 Long-distance runners wait
until the final sprint to
exceed their aerobic capacity
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 Cellular respiration
 Is the most prevalent
and efficient catabolic
pathway
 Consumes oxygen and
organic molecules such
as glucose
 Yields ATP
Respiration: exergonic (releases E)
C6H12O6 + 6O2  6H2O + 6CO2 + ATP (+ heat)
Photosynthesis: endergonic (requires E)
6H2O + 6CO2 + Light  C6H12O6 + 6O2
Respiration
Photosynthesis
Occurs in all
organisms
Occurs in only
chlorophyll containing
organisms
Breaks down glucose Stores light energy as
chemical energy in the
bonds of glucose
Releases carbon
Produces glucose and
dioxide, water, & ATP
oxygen
Exergonic Reaction
Endergonic reaction
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Cellular respiration can “burn” other kinds of
molecules besides glucose:
 Carbs
 Fats
 Proteins
Starch -> __??___ -> ATP
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 Cellular respiration and breathing are closely
related
 Respiration exchange gases with its
surroundings
 Cellular Respiration: exchanges these gases in
the cells
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Breathing
Lungs
Muscle
cells
Cellular
Respiration
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 Chemical reactions that transfer electrons from one
substance to another: oxidation-reduction reactions
 Oxidation: The loss of electrons and energy
 Reduction: The acceptance of electrons and energy
Oxidizing agent: e- acceptor
Reducing agent:
e- donor
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 Electrons are striped from GLUCOSE (oxidized)
 Electrons meet up with Protons to form H atom
 H atoms are transferred to electron carriers: NAD+ to make NADH
 Eventually meeting up with oxygen (reduced)
OILRIG!!!
becomes oxidized
Oxidation is a loss.
Reduction is a gain.
C6H12O6 + 6O2
6CO2 + 6H2O + Energy
becomes reduced
Glucose loses electrons (and hydrogens)
Oxidation
Glucose
Oxygen
Carbon
dioxide
Water
Reduction
Oxygen gains electrons (and hydrogens)]
Electrons travel downhill in an energy-yielding tumble (analagous
to gravity pulling objects) to find a more stable location.
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STEP BY STEP
 If electron transfer is not stepwise - A large release of
energy occurs.
 As in the reaction of hydrogen and oxygen to form water
ETC: Passes
electrons in a
series of steps
and uses the
energy from
the electron
transfer to
form ATP
 Cellular Respiration is a
metabolic pathway, not a
single reaction
 Many chemical reactions,
both aerobic and
anaerobic, are involved in
the process of cellular
respiration
 Lots of enzymes are
required for the process to
occur
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Print Student Lyrics
 Glycolysis – occurs in cytoplasm
 Formation of Acetyl CoA
 The Krebs cycle – occurs in matrix of mitochondria
 (Oxidative Phosphorylation) Electron transport –
occurs across the mitochondrial membrane
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You have to
spend money
to make
A ten-step process that occurs in the cytoplasm
of the cell
One glucose -> two molecules of pyruvic money!!!!
acid or pyruvate
(a 3-carbon molecule)
Anaerobic process - proceeds whether or not O2 is present
NET: 2 ATP per glucose molecule
NET: 2 NADH per glucose (a co-enzyme that serves as a
carrier for H+ ions liberated as glucose is oxidized.)
The pyruvic acid diffuses into the inner compartment of
the mitochondrion. Prepare pyruvic acid for entry into the
next stage of respiration.
 Pyruvate (3 Carbon Molecule)  Acetyl CoA (2 Carbon Molecule)
 CO2 and NADH produced
Oxidized?
Reduced?
 Occurs in mitochondrial matrix
 2 Pyruvate -> 2 Acetyl CoA  Citrate 
 Net gain after 2 turns: 2 ATP,
2 FADH2 (electron carrier)
Completes two turns through
the cycle.
CO2
released
4 CO2, 6 NADH,
Note: The six
original carbons
from glucose have
been released with
carbon dioxide. NO
CARBON REMAINS.
 Collection of proteins and carrier molecules embedded in inner
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membrane of mitochondria
Does not make ATP directly
The chain functions as a chemical machine that uses
energy released by the “fall” of electrons to pump
hydrogen ions across the inner mitochondrial membrane
These ions store potential energy
2 H+ + ½ O2  H2O
 NADH and FADH2 “shuttle” electrons to the electron
transport chain.
 The hydrogen atoms are split into hydrogen ion and
electrons.
H2 -> 2 H+ and 2eThey travel down until the reach the last electron
carrier – oxygen.
Oxygen combines with these electrons and
hydrogens to form water.
H2 -> 2 H+ and 2e-
ATP SYNTHASE harness the proton-motive force (gradient of
hydrogen ions) to phosphorylate ADP, forming ATP.
 H+ pumped from inner membrane
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to intermembrane space
H+ pump through ATP Synthase
(Enzyme)
On the other side is ADP and P
The pumping creates a gradient
(H gradient or proton gradient)
This potential energy creates ATP
Chemiosmosis uses stored
energy to drive cellular work
Electron Transport
Chain
Chemiosmosis
 Occurs in inner membrane  H+ ions pumped across
of mitochondria
inner mitochondrial
membrane
 Produces 26-28 ATP by
oxidative phosphorylation  H+ diffuse through ATP
via chemiosmosis
synthase (ADP  ATP)
ATP YIELD PER GLUCOSE 30-32
(Lower than earlier textbooks)
Mitochondrion
Cytosol
High-energy
electrons
carried
mainly by
NADH
High-energy
electrons
carried
by NADH
Glycolysis
Glucose
2
Pyruvic
acid
Krebs
Cycle
Electron
Transport
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Process
Location
Glycolysis
Formation of Acetyl CoA
Output
____ ATP (___ NET)
____ Pyruvates
2 NADH
Transported into Mighty
Mito
2 CO2
2 Acetyl CoA
2 NADH
Krebs/Citric
____ ATP
6 NADH
2 FADH2
ETC: Oxidative
Phosphorylation and
Chemiosmosis
____ ATP
2 H2O
____ ATP
Process
Location
Output
Glycolysis
Cytoplasm
4 ATP (2 NET)
2 Pyruvates
2 NADH
Formation of Acetyl CoA
Transported into Mighty
Mito
2 CO2
2 Acetyl CoA
2 NADH
Krebs/Citric
Matrix of Mito
2 ATP
6 NADH
2 FADH2
ETC: Oxidative
Phosphorylation and
Chemiosmosis
Inner Mito Mb
26-28 ATP
2 H2O
The MOST
NADH and
FADH2
30-32 ATP
Some of your cells can actually work for
short periods without oxygen
(anaerobic respiration)
For example, muscle cells can produce
ATP under anaerobic conditions
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 They can make ATP with / without oxygen
 They have enough ATP to support activities
such as quick sprinting for about 5 seconds
 A secondary supply of energy (creatine
phosphate) can keep muscle cells going for
another 10 seconds
 To keep running, your muscles must
generate ATP by the anaerobic process of
fermentation
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Without O2
Fermentation
 Keep glycolysis going
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by regenerating NAD+
Occurs in cytosol
No oxygen needed
Creates ethanol [+
CO2] or lactate
2 ATP (from glycolysis)
O2 present
Respiration
 Release E from
breakdown of food
with O2
 Occurs in
mitochondria
 O2 required (final
electron acceptor)
 Produces CO2, H2O
and up to 32 ATP
Alcohol fermentation
Lactic acid fermentation
 Pyruvate  Ethanol +
 Pyruvate  Lactate
CO2
 Ex. bacteria, yeast
 Used in brewing,
winemaking, baking
 Ex. fungi, bacteria, human
muscle cells
 Used to make cheese,
yogurt, acetone, methanol
 Note: Lactate build-up
does NOT causes muscle
fatigue and pain (old idea)
2 ADP+ 2
Glycolysis
2 NAD
2 NAD
Glucose
2 Pyruvic
acid
+ 2 H
2 Lactic
acid
Lactic acid fermentation
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2 ADP+ 2
2 CO2 released
2 ATP
Glycolysis
2 NAD
2 NAD
Glucose
2 Pyruvic
acid
2 Ethyl
alcohol
+ 2 H
Alcoholic fermentation
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 Obligate Anaerobes – only ferment, can’t
survive with oxygen
 Facultative anaerobes – both
(yeast/bacteria)
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aerobic cellular
respiration
(with O2)
ENERGY
glycolysis
anaerobic
(without O2)
(cytosol)
mitochondria
Fermentation
(cytosol)
pyruvate
oxidation
ethanol + CO2
(yeast, some bacteria)
citric acid
cycle
ETC
chemiosmosis
lactic acid
(animals)
oxidative
phosphorylation
What if you have high levels of ATP in the cell?
 Turn in your Case Study
 Cellular Respiration Pre-Lab Quiz
 Review Cellular Respiration, Finish Notes, Animation
 Take out Enzyme Lab and Pre-Lab, Leave on desk.
 Warm Up: Whisper Down the Lane *Prize*
 Peer Grading Metabolism FRQs (A, B, C)
What if you have high levels of ATP in the cell?
 Regulatory allosteric enzyme in glycolysis
 When ATP levels are high in the cell, the cell no longer
needs metabolic energy production to occur.
 In this case, PFK's activity is inhibited by allosteric
regulation by ATP itself, closing the valve on the flow
of carbohydrates through glycolysis.
 Recall that allosteric regulators bind to a different site
on the enzyme than the active (catalytic) site.
 Thus ATP binds in two places on PFK: in the active site
as a substrate and in the regulatory site as a negative
modulator.
 8 Steps
 Each catalyzed by a different enzyme
 First step synthesized by citrate synthase
 Acetyl Co-A joins Oxaloacetate to make citrate
 Transferring of carbon atoms and electrons
 We see lots of oxidation and reduction occurring
 This step makes the majority of NADH and FADH2
 1 ATP is generated per turn, 2 turns total
 Release of CO2 (No more carbon left in the pathway)
 Electron to the next one!
 Electrons fall “downhill” losing a small amount of energy
at each step
 Final destination? Oxygen – which has a high affinity for
electrons
Most of the ATP is produced during this
step. As electrons are relayed and
extracted.
Energy coupling:
Chemiosmosis couples
electron transport to ATP
synthesis
 Glycolysis is the most widespread metabolic pathway
today
 No membrane-bound organelles
(Prokaryotes)
 Ancient organisms probably used glycolysis exclusively
- long before oxygen was present in our environment
 Oldest fossils 3.5 billion years old
 Oxygen available 2.7 billion years ago
 Cyanobacteria
http://faculty.ccbcmd.edu/~gkaiser/biotutor
ials/cellresp/etsch.html
 Use the Q-Chart to create three leveled questions
about cellular respiration.
 I need a large pool of questions so please make your
own and do not copy from other students.
 I want to know YOUR questions, not your neighbor.
 Could be something you really don’t know.
 Or pose a question that you think would be good for
others.
Agenda:
 Cell Respiration Lab Part 1
HW:
 Identify 3 Enzymes with
their matching
substrates and products
as well as any medical
implications of someone
missing this enzyme.
AFTER SCHOOL CELL
RESPIRATION REVIEW
Agenda:
 Finish Cellular Respiration Part 1
 Write-Up Due Tomorrow