1. Cellular Respiration
 Cells convert
carbon from
glucose molecules
into carbon dioxide
and release energy
C6H12O6 + 6 O2  6 CO2 + 6 H2O + energy

2. Cellular Respiration
 Cells convert
carbon from
glucose molecules
into carbon dioxide
and release energy
C6H12O6 + 6 O2  6 CO2 + 6 H2O + energy

3. Cellular Respiration
 Energy released used to make ATP, main
energy source for cell processes
 Primary fuel for respiration is glucose

4. Glycolysis
 Occurs in cytoplasm
 Step 1: Phosphates from 2
ATP attach to a molecule of
glucose
 Step 2: These phosphates
destabilize the molecule and it
splits into 2 molecules of G3P

5. Glycolysis
 Step 3: After another phosphate is added, G3P
“reduces” NAD+ to NADH by adding electrons to
it

6. Glycolysis
 Step 4: 2
phosphates from
each molecule are
used to convert 2
ADPs into 2 ATPs
 Result is two 3-
carbon molecules
called “pyruvic acid”
or “pyruvate”

7. Terminology
 Reactions that require oxygen to take
place = aerobic
 Reactions that do not require oxygen
= anaerobic

8. Aerobic Respiration

9. Bridge Reaction
 Pyruvate is transported into
mitochondria
 Pyruvate releases 1 carbon in the
form of CO2 to become a compound
known as Acetyl-CoA (makes an
NADH)

10. Krebs Cycle
 Step 1: Acetyl-CoA (two
carbons) is then added to
oxaloacetic acid to create a
6-carbon molecule (called
citric acid)

11. Krebs Cycle
 Step 2: 2 CO2 molecules
released and 2 NADH
molecules created in
succession
 This results in a 4-carbon
molecule
 4-carbon is recycled into
oxaloacetic acid, creating
ATP, NADH, and FADH2

12. Electron Transport
 NADH and FADH2 donate
electrons to enzymes
along inner mitochondrial
membrane
 Energy from electrons
used in electron transport
chain to pump H+ ions out
of mitochondrial matrix
• Concentration gradient created

13. Chemiosmosis
 As in photosynthesis,
energy from the
diffusion of H+ used to
make ATP from ADP
 Leftover (used-up)
electrons and H+ that
has diffused into
mitochondria combine
with O2 to create H2O,
which is released

14. Electron Transport
 Even though some ATP is produced earlier,
most is produced here
 Without oxygen present, electron transport chain
and Krebs cycle stop

15. Efficiency of Respiration
 Actual number
of ATP created
from each
glucose varies
 Active transport
of NADH
consumes about
5% of energy
 Glycolysis
without the other
steps results in 2
ATP instead of
38!

17. Anaerobic Respiration

18. Fermentation
 Recycles NADH so glycolysis (ATP production)
can continue

19. Lactic Acid Fermentation
 Occurs in eukaryotes,
specifically humans &
animals
 Pyruvate can accept
electrons from NADH
and is converted to
lactic acid
 Lactic acid buildup
causes muscle
fatigue

20. Alcoholic Fermentation
 Occurs in plants, fungi
(yeast), prokaryotes
 CO2 released, converting
pyruvate to a 2-carbon
molecule
 Electrons added from NADH
to convert 2-carbon molecule
to ethanol

21. Alcoholic Fermentation
 Used to produce
alcoholic beverages
and “biofuel”
(ethanol)
 Used to make bread
rise (CO2)

22. A REVIEW

23. Photosynthesis
 CO2 + H2O + light energy  glucose + O2
 Autotrophs ONLY!
 Occurs in chloroplasts

24. Respiration
 glucose + O2  CO2 + H2O + energy
 BOTH atuotrophs and heterotrophs
 (ATP-heavy part) occurs in mitochondria