1. Cellular Respiration
pp. 174-178
Biology
Science Departm ent
Deerfield High School

2. Cellular Respiration
 Cellular respiration is the process by which
glucose (C6H12O6) is broken down to release
energy for making ATP, another form of
chemical energy.
Biology
Science Departm ent
Deerfield High School

3. Cellular Respiration – Equation
C6H12O6 + 6 O2 6 H2O + 6 CO2 + 36 ATP
food oxygen water carbon
(glucose, a carbohydrate) dioxide
Biology
Science Departm ent
Deerfield High School

4. BioTheme: Interdependence!
Photosynthesis:
6 H2O + 6 CO2 + energy (sun) → C6H12O6 + 6 O2
Cellular Respiration:
C6H12O6 + 6 O2 → 6 H2O + 6 CO2 + energy (ATP)
Biology
Science Departm ent
Deerfield High School

5. The BIG Question is…
Do only animals respire?
Or do plants respire too?
 Only plants perform photosynthesis
 Plants AND animals perform cellular
respiration!
(Can you explain why??)
Biology
Science Departm ent
Deerfield High School

6. Cellular Respiration Overview
Three Stages:
1. Glycolysis (o ccurs in bo th ae ro bic and anae ro bic)
2. Krebs Cycle
3. Electron Transport Chain
 The Main form of Energy produced =
ATP
Biology
Science Departm ent
Deerfield High School

7. Significant ATP Production
 Aerobic cellular respiration releases energy
SLOWLY, using oxygen to convert ONE
molecule of glucose to 36 ATP!
Biology
Science Departm ent
Deerfield High School

8. Cellular Respiration: An
Overview
Mitochondrion
Electrons carried in NADH
Electrons
Pyruvic
carried in
acid
NADH and
Glucose FADH2 Electron
Krebs Transport
Glycolysis
Cycle Chain
Mitochondrion
Cytoplasm
Biology
Science Departm ent
Deerfield High School

9. Glycolysis
 Glyco = Glucose lysis = Breakdown
 Occurs in the cytoplasm of the cell
 Molecules of GLUCOSE are broken down
into 2 molecules of Pyruvic Acid.
 Cell must use (invest) 2 ATP
 Products:
– 2 pyruvic acid
– 2 ATP
– 2 NADH
Biology
Science Departm ent
Deerfield High School

10. Glycolysis
Glucose
Pyruvi Pyruvi
c Acid c Acid
To the Electron
Transport Chain
Biology
Science Departm ent
Deerfield High School

11. Site of Cell Respiration
 The mitochondria is the
organelle where the final
stages of cellular respiration
occurs.
– Krebs Cycle
– Electron Transport Chain
Biology
Science Departm ent
Deerfield High School

12. Krebs Cycle
 Aerobic Process = Only if oxygen is present
 Occurs in the M RIX of the mitochondria
AT
 Pyruvic Acid from Glycolysis enters to form
– 2 AT P
– 6 NADH
–2F ADH 2
– CO2 (which is re le ase d whe n we e xhale !!)
 AKA Citric Acid Cycle
Biology
Science Departm ent
Deerfield High School

13. Krebs Cycle
Biology
Science Departm ent
Deerfield High School

14. Electron Transport Chain
 Energy carrier molecules produced during Glycolysis
and the Kreb’ s Cycle enter the ETC
– NADH
– FADH2
 Occurs in the folds of the Inner Membrane of the
Mitochondria (Cristae)
 The electrons are passed down a chain of proteins until
they reach the final electron acceptor…..oxygen!
– So this step is aerobic (requires oxygen)
 The ETC produces 32 AT and HO
P 2
Biology
Science Departm ent
Deerfield High School

15. Cellular Respiration Flowchart
Glucose Carbon
(C6H1206) Dioxide
Electron
Krebs (CO2)
+ Glycolysis Transport +
Cycle
Oxygen Chain Water
(02) (H2O)
Biology
Science Departm ent
Deerfield High School

16. Cellular Respiration (anaerobic)
 What happens when cells don’t have enough oxygen?
 Some organisms live in an oxygen-free environment.
The Kreb’s Cycle and Electron Transport
How do they get their energy?
Chain can’t function!!
These are anaerobic conditions!!
Biology
Science Departm ent
Deerfield High School

17. Minimal ATP Production
 In the absence of oxygen, anaerobic
respiration only releases 2 AT for each
P
molecule of glucose broken down.
Biology
Science Departm ent
Deerfield High School

18. Cellular Respiration (anaerobic)
 Anaerobic respiration is also called
fermentation, or the process by which
energy is released from glucose when
oxygen is NOT available.
 This process allows organisms to continue
to produce energy until oxygen is available.
 However, this process only releases 2 ATP
per molecule of glucose.
Biology
Science Departm ent
Deerfield High School

19. Fermentation
 Releases less energy than aerobic respiration
 Occurs in the Cytoplasm
– just like glycolysis
 Fermentation
– A series of reactions that convert NADH (from
glycolysis) back into NAD allowing glycolysis
to keep producing a small amount of ATP
Biology
Science Departm ent
Deerfield High School

20. Alcoholic Fermentation
 Anaerobic way of converting energy for
yeast and other microorganisms
 Glucose broken down to produce alcohol,
CO2 and energy (ATP)
 C6H12O6 + pyruvic acid  ethanol + CO2 + 2 ATP
 EX: baking bread with yeast (dough rises)
fermenting wine & beer
Biology
Science Departm ent
Deerfield High School

21. Lactic Acid Fermentation
 Anaerobic way of converting energy in
animal cells and some microorganisms
 Glucose broken down to produce lactic
acid, CO2 and energy (ATP)
 C6H12O6 + pyruvic acid  lactic acid + 2 ATP
 EX: muscle cells during strenuous exercise
fermenting cheese, yogurt, sour cream
Biology
Science Departm ent
Deerfield High School

22. Lactic Acid Fermentation
– Occurs in bacteria (unicellular organisms)
– This is how cheese, yogurt, and pickles are made.
– Occurs in muscles during rapid exercise
– When your body runs out of oxygen your muscle cells must
produce some ATP using fermentation and glycolysis
– Lactic Acid build-up causes muscle soreness or burning
after intense activity.
Pyruvic Acid + NADH → lactic acid + NAD+
Biology
Science Departm ent
Deerfield High School

23. Strenuous Exercise
 Lactic acid is produced by your muscle
cells during rapid exercise when the body
cannot supply enough O2 to tissues.
 Without enough O2, the body is NOT able to
produce all of the ATP that is required.
 The buildup of lactic acid can cause painful
burning in your muscles
Biology
Science Departm ent
Deerfield High School

24. Fermentation Summary
Glycolysis: Glucose → 2 Pyruvic Acid Fermentation: 2 Pyruvic Acid → ? or ?
Biology
Science Departm ent
Deerfield High School

25. Chemical Pathways
Glucose
Glycolysis Krebs Electron
cycle transport
Fermentation Alcohol or
(without oxygen) Lactic Acid
Biology
Science Departm ent
Deerfield High School

26. Comparing ATP Production
 First, your body breaks down glucose through aerobic
respiration to produce 36 AT per glucose molecule;
P
however, this is a slow process.
 When muscle cells cannot get enough O2 they break down
glucose through lactic acid fermentation to produce 2
AT per glucose…
P
 Therefore, AEROBIC RESPIRATION is much
more efficient in terms of ATP production – 36
ATP compared to 2 ATP!
Biology
Science Departm ent
Deerfield High School

27. Aerobic Training
 Ex: long runs, biking, swimming
 Can increase the size and number of
mitochondria in muscle cells
 Can increase the delivery of O2 to muscles by
improving the heart and lungs
Biology
Science Departm ent
Deerfield High School

28. Anaerobic Training
 Ex: sprints, strides,
quick bursts of energy
 Increase the glycogen levels in the muscles
 Increase body’ s tolerance to lactic acid
Biology
Science Departm ent
Deerfield High School