Transcript Respiration Notes

Cellular Respiration
Chapter 9
Cellular Respiration
• Process by which mitochondria break down
food molecules to make ATP
• C6H12O6 + O2  CO2 + H2O + Energy
• Three Stages:
– Glycolysis
– Citric Acid Cycle (Krebs Cycle)
– Electron Transport Chain
Anaerobic vs. Aerobic
Anaerobic
• Without oxygen
• Glycolysis, Fermentation
• Obligate Anaerobe
– Cannot survive in the
presence of oxygen
– Tetanus
• Facultative Anaerobe
– Can use oxygen, but can
survive in its absence
– Yeast
Aerobic
• Uses Oxygen
• Krebs and e- transport
chain
• Produces a lot more
energy
Glycolysis
• Occurs in the cytoplasm of the cell
• Breaks down glucose ( 6-Carbon) into 2
pyruvic acid (3-Carbon)
• Makes 4 ATP, but uses 2 ATP = 2 ATP
• NAD+ accepts electrons to become NADH
– Those e- move to the e- transport chain
Summary: Glycolysis makes 2 ATP, NADH, and 2 pyruvic acid.
Citric Acid Cycle
• Begins after pyruvic acid is transformed into
acetyl-CoA (this rxn also makes NADH)
• Occurs in the matrix of the mitochondria
• For every turn of the cycle the following are
made:
–
–
–
–
1 ATP
2 CO2
3 NADH
1 FADH2
• This cycle happens twice for each glucose
Electron Transport Chain
• Located in the inner membrane of the
mitochondria
• Similar to the e- transport chain in photosynthesis
• NADH and FADH2 supply the energized e• ATP is produced and H+ is pumped into the
matrix of the mitochondria
• As the ATP moves out of the mitochondria more
ATP is made
• Oxygen is the final e- acceptor at the end of the
chain – results in the formation of water
• Makes 32 ATP
Summary of Cellular Respiration
Glycolysis
ATP
NADH
2 net
(4 total)
2
Pyruvate
2
CO2
AcetylCoA
Pyruvic
acid to
Acetyl-CoA
Krebs (In 2
turns)
2
Electron
Transport
Chain
32
6
FADH2
2
Other
Products
CO2
H2O
The 36 ATP produced in cellular
respiration represent only about
38% of the energy stored in the
sugar – the rest of the energy is
released as heat
What if no oxygen is available?
• Glycolysis will continue, but if NAD+ is
not recycled it will stop, too.
• Less energy is produced – only 2 ATP
• Fermentation – cycles the NAD back to
glycolysis, but does not produce energy
Fermentation
Lactic Acid Fermentation
• Makes lactic acid, CO2,
and NAD+
• Occurs in muscles when
an oxygen debt is
created
Alcoholic Fermentation
• Makes alcohol, CO2, and
NAD+
• Yeast and some bacteria