Cellular Respiration
Remember
• 1. ETC is a series of Redox on a membrane
used to create a [] leading to PE.
• 2. CHOs are made in photosynthesis
Energy Coupling between
Photosynthesis and Cellular
Respiration
Light
energy
ECOSYSTEM
CO2 + H2O
Photosynthesis
in chloroplasts
Cellular respiration
in mitochondria
Organic+ O
molecules 2
ATP
powers most cellular work
Heat
energy
Cell Respiration is Catabolism
•
•
•
•
•
Use O2 to make ATP.
With O2 energy is made in mitochondria
Without O2 energy is made in cytoplasm
- G because its catabolic and exergonic.
There is free energy to do work.
Catabolism
• Process where molecules are broken down,
and their energy is released. Two types.
• Fermentation-partial degradation of sugars
that occurs without the use of oxygen.
(anerobic respiration)
• Cellular respiration- most prevalent and
efficient metabolic pathway. Oxygen is
consumed as a reactant along with organic
fuel. (aerobic respiration)
Photosynthesis and Cellular Respiration
chemical reactions
(Remember… conservation of matter.)
6 CO2 + 6 H2O  C6H12O6 + 6 O2 +
Heat
Photosynthesis
C6H12O6 + 6O2  6CO2 + 6H2O + Heat +
Free E
Cellular Respiration
ATP Structure
Cell Respiration has 3 steps
• 1. Glycolysis
• 2. Kreb’s Cycle or CAC
• 3. ETC aka Oxidative Phosphorylation aka
Chemiosmosis
Glycolysis
• Occurs in cytosol
• This process occurs with/
without O2 in the cytolasm.
• All organisms can do
this…evolution…life before
O2.
• Glycolysis Animation
• Better Glycolysis Animation
Glycolysis Step-by-Step
• 1. Start with a 6C hexose sugar.
• 2. 2 PO4 are added to glucose using up 2ATP creating
a 6C sugar diphosphate +2ADP.
• 3. 6C sugar splits into 2 G3P molecules.
• 4. NAD+ (e- carrier) adds PO4, removes a H+ from
the 3C sugar and turns into NADH . The 2 G3P
sugars turn into 2 3C sugars called pyruvate by the
removal of both phosphates.
• 5. Each 3C sugar yields 2ATP when converted from
sugar phosphate to pyruvate.
Summary of Glycolysis
I. Glycolysis-cytoplasmGlucose----> 2 pyruvic acid
2NAD + 2H---->2NADH
2ATP---->2ADP + 2P
4ADP + 4P----> 4ATP
NET 2 ATP for cell use
After Glycoysis
• If oxygen is present: aerobic respiration
– Aerobic respiration= glycolysis+CAC+OP
• If oxygen is absent: anerobic respiration
– Anerobic respiration =glycolysis + fermentation
Is Oxygen present?
Fermentation
• Two types of Fermentation:
– 1. Alcohol fermentation- pyruvate is converted
into ethanol.
– 2. Lactic acid fermentation- pyruvate is reduced
(gains electrons from NADH+). (NADH+
NAD+)Lactate formed as waste product.
Cellular Respiration
• Carbohydrates, fats, and proteins can all be
broken down by C.R.
• Glucose most common molecule broken
down by aerobic respiration.
• 6O2 + C6H12O6 --> 6H2O + 6CO2 + energy
• Exergonic release of energy is used to
phosphorylate ADP to ATP.
• The goal of cellular respiration is to regenerate
ATP that is used by cells as main energy
source. (ADP + P ATP)
Oxidation-Reduction Reactions
• Cellular Respiration - YouTube
• Cellular respiration is an example of an
oxidation reduction reaction. (Redox for short)
• In redox reactions electrons are transferred
from one reactant to another.
• When a reactant loses electrons it is called
oxidation. This causes a loss of energy.
• When a reactant gains electrons it is reduced.
This causes a gain of energy
Another way a cell uses energy is by moving hydrogen, and electrons
around. Giving a molecule hydrogen, increases the energy content of that
molecule .
For example compare gasoline with carbon dioxide. Which has more
energy? Now look at their molecular structure
Oxidizing a molecule, decreases the energy content of that molecule and
reducing a molecule increases the energy content of that molecule.
Oxidized
Reduce
1. Remove H
1. Add H
2. Remove e-
2. Add e-
3. Add oxygen
3.Remove oxygen
When NAD+ gains 2 electrons and hydrogen it is called NADH and when
NADP+ gains 2 electrons and hydrogen it is called NADPH. Look at NAD+
and NADH and see where the extra hydrogen is
Compare FAD and FADH2 and determine what is the difference between
these two hydrogen carriers.
Following Glycolysis with
Oxygen
• Glycolysis takes place in cytosol.
• If oxygen is present, the pyruvate goes into
the mitochondria to complete the second
stage of cellular respiration: Citric Acid
Cycle aka Kreb’s Cycle
Citric Acid Cycle
• Citric Acid Cycle
• Main purpose of
Kreb’s is to make
electron carriers for
Citric Acid Cycle Step by Step
• 1. Pyruvate (3C) loses CO2, becomes 2C,
NAD is reduced to NADH +H+, Coenzyme
A joins the molecule and is now called
Acetyl-CoA (2).
– Happens between outer and inner m. membrane
• 2. Acetyl CoA joins a 4C molecule forming
a 6C molecule and Coenzyme A is released.
• 3. 6C molecule is oxidized, another NAD+
is reduced to NADH, CO2 is released, and
5C molecule results.
• 4. 5C molecule oxidized again, another
NAD+ reduced to NADH, CO2 released,
1ATP generated, and a 4C molecule results.
• 5. 4C molecule is oxidized, FADH to
FADH2, NAD+ TO NADH, and the 4C
molecule is ready to rejoin the acetyl CoA
and start the cycle again.
• Citric Acid Cycle
CoA
Actual Kreb’s Cycle
Summary of Krebs- Occurs in mitochondrion
2X’s
Pyruvate---> 3 CO2
6 CO2
1 ADP ---> 1 ATP
2 ATP
4 NAD ---> 4 NADH2
8 NADH
1 FAD ---> 1 FADH2
2 FADH2
The hydrogen found on pyruvate will be used to reduce NAD and
FAD. Only one ADP is phosphorylated at the substrate level or
directly by enzymes.
Glycolysis and Citric Acid Cycle
are both substrate level
phosphorylation
Step 3 of Cellular Respiration utilizes
the process of oxidative
phosphorylation.
Step 3:Oxidative Phosphorylation
aka Chemiosmosis
• Located in cristae of mitochondria is the electron
transport chain. More folds=more ATP produced.
• ETC will make more ATP using NADH &
FADH2.
• Electrons from NADH & FADH2 will move
down the ETC and pump H+ across the cristae
membrane.
• NADH & FADH are oxidized, and ADP is
phosphorylated.
Oxidative Phosphorylation
• Each NADH =6H+
• Each FADH2=4H+
• ~2H+=1ATP
• Notice outside the the
difference in (+) and (-)
• ATP synthase uses the
osmotic difference to
allow H+ to go back
into the matrix.
• Oxygen is the final eacceptor.
8 NADH2 x 6 H
= 48 H+
2 FADH2(Krebs)x 4 H = 8 H+
2 FADH2(glyc.) X 4 H = 8 H+
64 H+
ATP Summary
64 H+ --> 32 ATP
Electron Transport Chain
• Electron transport chain powered by
electrons from NADH and FADH.
• As these electrons lose energy, that energy
is used to pump H+ into intermembrane
space.
• At end of ETC, hydrogen bonds to oxygen
to form water. No oxygen the process stops.
• Cellular Respiration (Electron Transport
Chain)
• ATP Synthase
Chemiosmosis
• Hydrogen ions will flow back down
concentration gradient through a
transmembrane protein called ATP
synthase.
• The H ions provide a concentration gradient
(fuel) that drives ATP synthesis.
• ADPATP in this step
Oxidative Phosphorylation
• This term is used because ADP is
phosphorylated into ATP, and oxygen is
necessary to keep electrons flowing in the
ETC.
• Total ATP Yield for Cellular Respiration:
36-38 ATP.
• 32-34 ATP come from oxidative
phosphorylation.
“Building” the proton concentration
gradient
Inner
mitochondrial
membrane
Glycolysis
Citric
acid
cycle
ATP
ATP
Oxidative
phosphorylation:
electron transport
and chemiosmosis
ATP
H+
H+
H+
H+
Intermembrane
space
Cyt c
Protein complex
of electron
carriers
Q
IV
III
I
ATP
synthase
II
Inner
mitochondrial
membrane
FADH2
NADH + H+
2H+ + 1/2 O2
NAD+
ATP
ADP + P i
(carrying electrons
from food)
Mitochondrial
matrix
H2O
FAD
H+
Electron transport chain
Electron transport and pumping of protons (H+),
Which create an H+ gradient across the membrane
Oxidative phosphorylation
Chemiosmosis
ATP synthesis powered by the flow
of H+ back across the membrane
ATP Synthetase Complex using
kinetic movement of H+ (protons)
ATP WEBSITE
•
•
•
•
ATPl
Oxidative Phosphorylation Animation
You Tube- ox phos
cellrespiration review song- Black Eyed
Peas
Data Set 4 Picture
C
A
B
D
• The correct answer is B. This species is not struggling to exist. The
environment is very favorable as it is making and storing more energy
than it is consuming on metabolism, growth, repair, and reproduction.
It has energy to spare.
•
• Answer A is incorrect because species B is consuming more energy
than it can produce. It must be a harsh environment because it is
consuming more energy trying to “stay alive”. At this pace, it will
eventually die from an energy production deficit.
• Answer C is incorrect because species D, while very much in the “high
green” part of the curve, is only still at the
• breakeven point on the y axis. Life is a struggle to exist here because
any little disruption to the environment may put the species in a energy
deficit situation where Cellular respiration is consuming more energy
than being produced.
• Answer D is incorrect for same reason as answer C.
Cellular Respiration Lab (Lab #5)
• Lab 5 Set Up
• Make sure to time
calibration times!
• Practice drawing cell
respiration on boards
in down time.
• Practice writing out
steps in down time.
• Begin answering
questions.