Download Cellular Respiration

Cellular
Respiration
(Extracting energy from food)
Phelan Ch 4.4, p143-153
Krogh Ch 7
ALL ORGANISMS HAVE AN ENERGY BUDGET!
Remember ATP?

All cells use ATP energy for work like…
–
–
–
–
Movement
Growing
Repairing tissues
Heating you up
but… ATP is so unstable that it cannot be stored
long term…
 so cells must constantly use energy from sun,
heat, or food to recharge it.
 ATP  ADP + Pi + ENERGY!

How ATP is used as a ‘battery’

Coupled Reactions = pairing an exergonic
reaction with an endergonic one
Phosphorylation powers enzymes
Gummy bear SACRIFICE!
Remember the poor
gummy bear?
 The point?
 Enzymes must
release stored energy
slowly, step by step… you
don’t want your cells to
combust!

Big Idea:

Organisms store E as large organic
molecules… split them apart in a
CONTROLLED fashion when ATP is needed

Calories refer to potential energy in the
food you’ve consumed
– Ex. 3,811 calories/g glucose
– 1 Cal = 1,000 calories
– Roughly 4 Cal/g in sugar
Meet
+
NAD !
Similar to NADP+
 Gradually rips high energy hydrogen
electrons from food… NAD+  NADH
 carries them to an electron transport chain in
mitochondrion membrane used to help run
ATP Synthase

2 WAYS CELLS
MAKE ATP FROM FOOD
Aerobic Resp
(with O2)
Anaerobic Resp
(no O2)
FERMENTATION
Glycolysis
“Splitting sugar”
 ALL cells use special enzymes to
perform this in the cytoplasm.
 Destabilize sugar by adding
phosphates. Let it split down middle.
Pull off a few of the hydrogens.
(Actually takes 10 steps!)
 Net:

– 2 ATP
– 2 NADH
– 2 Pyruvic Acid (3C each)
 fate is determined by presence or lack of O
Note: because NAD+
already ripped off
some H, pyruvate’s
formula is C3H4O3
The real version of glycolysis if you’re
interested! Do NOT need to memorize!
PYRUVATE FROM
GLYCOLYSIS
Aerobic Resp
(with O2)
Anaerobic Resp
(no O2)
FERMENTATION
What if you DO HAVE oxygen?
Aerobic Cell Respiration
Cells with O2 can finish pyruvate
breakdown using Krebs Cycle and
Electron Transport Chain
 34 additional ATP! 
 C6H12O6 + 6O2  6CO2 +6 H20 + 36 ATP


Mitochondria
– eukaryotic “power plant”
– high surface area
An analogy:
Write this down!!!!!!
Mitochondrion anatomy
(aerobic cont.)

Mitochondria add 2 phases after glycolysis…
– Krebs Cycle (Citric Acid Cycle):
 finishes sugar breakdown!
 In mitochondrial matrix
 Produces NADH, FADH2, CO2 &
2 ATP
– Electron Transport Chain:
 NADH and FADH2 drop e- along inner mitochondrion
membrane
 Driven by electronegativity of O2 (final e- acceptor)
 Proton (H+) gradient established for ATP Synthase
 Produces H2O & 32 ATP
Krebs
Cycle
OUCH
Pyruvate
Pyruvate
dehydrogenase
That’s
better
The Electron Transport Chain
The complete aerobic process
Don’t always use glucose