Cellular Respiration ch 8
Cellular Respiration
Have you ever wondered why
exactly you need to breathe? What
happens when you stop breathing?
Cellular respiration is
the set of the
metabolic reactions
and processes that
take place in the cells
of organisms to
convert biochemical
energy from nutrients
into adenosine
triphosphate (ATP),
and then release
waste products.
Mitochondria!
C6H12O6 + 6O2 -->6 CO2 + 6H2O + 36 ATP
How are they connected?
Heterotrophs
making energy & organic molecules from ingesting organic molecules
glucose + oxygen  carbon + water + energy
dioxide
C6H12O6 +
6O2
 6CO2 + 6H2O + ATP
oxidation = exergonic
Autotrophs
making energy & organic molecules from light energy
Where’s
the ATP?
carbon + water + energy  glucose + oxygen
dioxide
6CO2 + 6H2O +light

energy
reduction = endergonic
C6H12O6
+ 6O2
O2 or no O2
Aerobic Respiration: requires oxygen
(air)
(breathing)
Anaerobic Respiration: does not need oxygen
(no air) (breathing)
AEROBIC = with oxygen, occurs in the
presence of oxygen - in mitochondira
Without oxygen,
another path is taken
....this path is called
fermentation, or
Anaerobic = without
oxygen, in cytosol
There are three stages
1. Glycolysis
2. Kreb's Cycle (Citric Acid Cycle)
3. Electron Transport Chain
GLYCOLYSIS
can occur without
oxygen
GLYCOLYSIS = "glyco - lysis " is the splitting of a 6
carbon glucose into two pyruvates, each having 3
carbons
net yield of 2 ATP per glucose molecule
net yield of 2 NADH per glucose molecule
QOD
1. What does cellular respiration
produce?
2. Does it need light?
3. What does anaerobic mean?
4. What does aerobic mean?
5. What is the equation for cellular
respirations?
Stage 1: Glycolysis:
•
•
•
•
Anaerobic = no O2 needed
Occurs in cytoplasm
Occurs in all organisms
Net of 2ATP
Products:
2 ATP
2 NADH
2 Pyruvic Acids
Stage 1: Glycolysis:
•
•
•
•
Anaerobic = no O2 needed
Occurs in cytoplasm
Occurs in all organisms
Net of 2ATP
Products:
2 ATP
2 NADH
2 Pyruvic Acids
Equation for Cellular Respiration:
oxidation & reduction
• REDOX reactions in respiration
– release energy as breakdown organic molecules
• break C-C bonds
• strip off electrons from C-H bonds by removing H atoms
– C6H12O6  CO2 = the fuel has been oxidized
• electrons attracted to more electronegative atoms
– in biology, the most electronegative atom?
– O2  H2O = oxygen has been reduced
– couple REDOX reactions &
use the released energy to synthesize ATP
*Need
mitochondria
and enzymes
to make this
happen!
oxidation
C6H12O6 + 6O2
 6CO2 + 6H2O + 36ATP
reduction
or 38
Mitochondria: power house
Label
on your
paper
2. Citric Acid or Krebs Cycle
Hans Krebs
1900-1981
It is not
necessary to
know the
individual steps
-
-
occur ONLY if oxygen is present and the cell has
mitochondria.
In this stage of cellular respiration, the oxidation of glucose to
CO2 is completed. (this is why we exhale carbon dioxide)
Pre Krebs: The
pyruvic acid (C3) loses
a C to CO2 and use a H
+ to form NADH and
becomes Acetyl Co-A
(C2).
Simple put: Pyruvate is
converted to Acetly CoA
– releases 2 CO2
– reduces 2 NAD  2 NADH
(moves e-)
– produces 2 acetyl CoA
• Acetyl CoA enters
Krebs cycle
Krebs Cycle Overview
Citric acid
Aerobic
Occurs in the
matrix (inner
compartment)
Products (per
glucose)
2 ATP
6 CO2
8 NADH
2 FADH2.
These energy carriers now enter the electron
transport chain (ETC).
Count the C & electron carriers!
pyruvate
3C
FADH2
6C
4C
NADH
This happens
twice for each
glucose
molecule
2C
4C
acetyl CoA
citrate
reduction
of electron
carriers
x2
4C
4C
ATP
CO2
NADH
6C
CO2
NADH
5C
4C
CO2
NADH
3. Electron Transport System:
Oxidative Phosphorylation: process in which ATP
is formed as a result of the transfer of electrons
from NADH or FADH 2 to O 2 by a series of electron
carriers.
• As opposed to photophosphorylation….
ETC
Does this picture look familiar?
You've seen this before in
photosynthesis.
Products:
Animation of the ETC McGraw Hill
34 ATP
Animation
McGraw Hill Animation
NAD
dehydrogenase
Coenzyme
Bc complex
Q
Coenzyme c
NADH
Cytochrome c
oxidase complex
FADH
ADP
McGraw Hill Animation
ATP synthase
NAD
dehydrogenase
Coenzyme
Q
Bc complex
Coenzyme c
NADH
Cytochrome c oxidase
complex
FADH
H2O
ADP
McGraw Hill Animation
ATP synthase
NAD
dehydrogenase
Coenzyme
Bc complex
Q
Coenzyme c
NADH
Cytochrome c
oxidase complex
FADH
H2O
ADP
McGraw Hill Animation
ATP synthase
-net yield of 32 or 34 ATP per glucose molecule
- 6 H2O are formed when the electrons unite with O2* at the
end of electron transport chain.
* We breath because we need oxygen as the final electron
acceptor! The resulting ATP is able to leave the mitochondria
by the ATP transport protein in the membrane. It goes to
wherever it is needed in the cell.
Without
oxygen to
serve as the
final electron
acceptor, the
process
shuts down.
Breakdown of One Glucose Molecule
Calculations from each:
Theoretical
NADH= 2 or 3 ATP can be made
Yield
FADH2= 2 ATP can be made
1. Glycolysis – Produces:
2 ATP
2 NADH
2. Krebs Cycle (including “pre-Kreb’s”) - Produces:
2 ATP
8 NADH
2FADH2
Total:
4ATP
3. ETC - Produces:
10 NADH
x3
30 ATP
2 FADH2
x2
4 ATP = 34 ATP
Total: 4ATP + 34 ATP + a grand total of 38 ATP !
For simplicity, however, we look at the theoretical maximum
yield of ATP per glucose molecule oxidized by aerobic
respiration.
http://www.youtube.com/watch?v=j7gPtASv0SQ
http://www.youtube.com/watch?v=0IJMRsTcwcg
Determining the exact yield of ATP for aerobic respiration is difficult for
a number of reasons.
- bacteria may differ in their carriers in the ETC
- the number of ATP generated per reduced NADH or FADH2 is
not always a whole number.
For every pair of electrons transported to the electron
transport chain by a molecule of NADH, between 2
and 3 ATP are generated. For each pair of electrons
transferred by FADH2, between 1 and 2 ATP are
generated.
For simplicity, however, we look at the theoretical
maximum yield of ATP per glucose molecule
oxidized by aerobic respiration.
Cellular Respiration Summary
1
4
2
- Each NADH
produces 3 ATP
- Each FADH2
produces 2 ATP
23
5
2 6net
2 7net
8NADH
9
10
34 11
Cellular Respiration Summary
2 NADH
6 NADH
2 FADH2
- Each NADH
produces 3 ATP
- Each FADH2
produces 2 ATP
2 NADH
2 ATP
2 ATP net
2 ATP net
8 NADH
2 FADH2
6 CO2
34 ATP possible
What happens if you don’t get enough
oxygen?
Fermentation: use of pyruvate to make
minimal ATP when there is no O2 = anaerobic
This happens when the
Krebs cycle cannot occur
due to lack of oxygen
By products of
fermentation include lactic
acid and alcohol
Lactic Acid in muscle cells
can cause muscle
cramps.
Two Types:
1. Lactic Acid
Fermentation: in
animals, turns
pyruvate into lactic
acid
2. Alcoholic
Fermentation: in
yeast and bacteria,
turns pyruvate into
ethyl alcohol
C3
pyruvic acid
C3
pyruvic acid
OR
C02
3 Carbon Compound
NAD+
2 Carbon Compound
NADH + H+
NAD+
NADH + H+
Lactic Acid
Ethyl Alcohol
If not enough O2 IS present in ANIMALS
The pyruvic acid is converted to Lactic acid + 2 ATP
This makes muscles fatigue and get sore.
In anaerobic BACTERIA…
The pyruvic acid is converted to Lactic acid + 2 ATP
This sours milk and makes yogurt and cheese.
LACTIC ACID FERMENTATION: C6H12O6
2 C3H6O3 + 2 ATP
(Lactic Acid)
OR
In YEAST…
The pyruvic acid is converted to Alcohol +CO2 + 2ATP
This makes alcoholic beverages, also alcohol for alcohol cars.
The baking industry uses the CO2 to make bread rise.
ALCOHOLIC FERMENTATION: C6H12O6
2C2H6O + 2CO2 + 2 ATP
(Ethyl Alcohol)
Fermentation
This happens when the
Krebs cycle cannot occur
due to lack of oxygen
Byproducts of
fermentation include lactic
acid and alcohol
Lactic Acid in muscle cells
can cause muscle
cramps.
Fermentation
This happens when the
Krebs cycle cannot occur
due to lack of oxygen
Byproducts of
fermentation include lactic
acid and alcohol
Lactic Acid in muscle cells
can cause muscle
cramps.
Applications of
fermentation
Fermentation is used in
making food products and
alcohol products.
http://www.dnatube.com/video/5784/What-Exactly-isFermentation
Aka/ Other Vocab:
Oxidative Phosphorylation: (aka ETC of cellular
respirations) process in which ATP is formed as a
result of the transfer of electrons from NADH or
FADH 2 to O 2 by a series of electron carriers.
Pre Kreps = Prep Reactions
Kreb Cycle= Citric Acid Cycle
Why?
Substrate Level ATPsynthase= glycolysis and Kreb
cycle together
GTP: Guanosine-5'-triphosphate- GTP is involved in
energy transfer within the cell, a GTP molecule is
generated by one of the enzymes in the citric acid cycle.
This is leads to the generation of one molecule of ATP,
since GTP is readily converted to ATP.
Why is it
called the
citric acid
cycle?
Is the Mitochondrial Genome Still Functional?
Evidence of Endosymbiosis:
Mitochondrial genomes are very small and show a great deal of
variation as a result of divergent evolution. Mitochondrial genes
that have been conserved across evolution include rRNA genes,
tRNA genes, and a small number of genes that encode proteins
involved in electron transport and ATP synthesis.
The mitochondrial genome retains similarity to its prokaryotic
ancestor, as does some of the machinery mitochondria use to
synthesize proteins. In fact, mitochondrial rRNAs more closely
resemble bacterial rRNAs than the eukaryotic rRNAs found in
cell cytoplasm. In addition, some of the codons that mitochondria
use to specify amino acids differ from the standard eukaryotic
codons.
Mitochondrial Disease
In school, children with mitochondrial disease often seem to
work in “spurts” and then “peter out,” becoming lethargic and
finding it difficult to concentrate.
It ranges from intermittent difficulty thinking, remembering,
moving and acting, to severe handicaps. Some results may
be fatigue, muscle weakness and diabetes.
What do you think, at the molecular level, is causing these
symptoms?
What are the 3 stages
of cellular respiration?
1.
2.
3.
Food for thought
1. What is the purpose of cellular respiration?
2. Where does cellular respiration occur within the cell?
3. What is the waste product of cellular respiration?
Would you go to
an oxygen bar?
4. Compare Photosynthesis to Respiration
a. Where does each occur?
b. What are the products of each?
c. What compounds are needed to start the processes?
d. What is the function of the electron transport chain in each
process
e. Describe the role of ATPase in both processes.
Photosynthesis – Respiration Cycle
Photophosphorylation vs Oxidative Phosphorylation:
Self Test
1. In order to produce energy, cells start with glycolysis. If oxygen is
NOT present after glycolysis, what process occurs next?
a) Electron Transport Chain b) Krebs Cycle c) Fermentation
2. If oxygen IS present after glycolysis, what process occurs next?
a) Electron Transport Chain b) Krebs Cycle c)Fermentation
3. A process that does NOT require oxygen is known as what?
a) Aerobic
b) Anaerobic
4. In glycolysis, glucose is broken into 2 molecules of
__________________ acid
5. Where does the Kreb's cycle occur? _________________
6. What gas is a waste product produced in the Krebs cycle? ____
7. What enzyme is used in the electron transport chain to
create ATP?
a. citric acid
b. pyruvate
c. ATPase
8. Where does glycolyis occur?
a. cytoplasm
b. mitochondria
c. chloroplast
9. Which process produces the largest amount of ATP?
a. fermentation
b. Krebs Cycle
c. ETC
10. The oxygen required by cellular respiration is reduced and
becomes part of which molecule?
a. ATP
b. CO2
c. H20
The Mystery of the Seven Deaths
Case
Study: http://sciencecases.lib.buffalo.edu/cs/files/cellular_respiration.pdf
In this case study, students learn about the function of cellular respiration and
the electron transport chain and what happens when that function is impaired.
Students play the role of medical examiner as they analyze the autopsy results
to determine the cause of the mysterious deaths of these seven victims.
• Explain the overall purpose of cellular respiration.
• Describe the intermediate metabolites of cellular respiration.
• Explain the function and importance of the electron transport chain.
• Describe the role of oxygen in cellular respiration
trophic level: each step in a food chain
or food web, feeding level
Third level Consumer
Secondary Consumers
Primary Consumer
Producer
Tropic levels
• 10% of the energy at one trophic level
is available for organisms at the next
trophic level.
• 90% is used for metabolic activity and
is given off as heat.
Tropic levels clip 60369