Transcript 6-3 Aerobic Respiration

6-3 Aerobic Respiration
How much ATP is produced in
anaerobic respiration?
2 ATP
Pyruvic acid, the end product of
anaerobic respiration has almost as
much energy as does glucose…
Aerobic respiration continued…
In order for pyruvic acid to be broken
down, yielding further energy, 2 things
are required:
1) Oxygen (O2)
2) Mitochondria
Breaking pyruvic acid…
Once pyruvic acid enters the
mitochondrion, it is broken into a 2
carbon molecule, which bonds to an
enzyme called coenzyme A (CoA) to
form acetyl CoA.
Each molecule of pyruvic acid yields 1
CO2, and 1 NADH
Pyruvic Acid
NAD+
NADH
CO2
CoA
Krebs here I come!!!
Once the acetyl-CoA is formed, it
enters into what is called the Kreb’s
Cycle, or Citric Acid Cycle.
What is a cycle?
A repeating series of events…
Except for the acetyl-CoA, everything
else in the cycle is reused.
Krebs again…
For every “turn” of the Kreb’s cycle:
• 1 acetyl-CoA is required
• 2 molecules of CO2 are made
• 3 molecules of NADH are made
• 1 molecule of FADH2 is made
Interesting tidbits…
For every turn of the Kreb’s cycle,
only 1 ATP is produced!!!
Anyone recall how much ATP comes
out of aerobic respiration?
36ATP!!!
Where does the rest of the energy come
from?
Working on the chain…
Well, we haven’t seen much ATP made
yet, but what has been happening?
REDUCTION OF NAD+ & FAD!!!
We’ve got 10 NADH at this point and
2 FADH2! That’s a lot of stored
energy.
Where does it go?
The energy stored in NADH and
FADH2 is released in a series of steps
called the electron transport chain.
The ETC is simply a series of step in
which electrons are passed from carrier
to carrier, until finally O2 accepts the
last 2 electrons.
Ahhh, big words…
As electrons are passed, energy is
passed as well…
Some of that energy is used to convert
ADP to ATP by means of a H+ pump
(don’t worry about this!).
The last step…
Again, O2 is the final electron
acceptor. It combines with 4 H, to
form… WATER!!!
All in all, we gain 2 ATP from
glycolysis, 2 ATP from the Kreb’s, and
32 from the ETC for a total of 36 ATP
gained!!!
Net Reactions:
The overall process we have talked
about can be summarized as:
C6H12O6 + 6 H2O + 6 O2
6 CO2 + 12 H2O + 36 ATP
Recap:
Why do aerobic respiration instead
of anaerobic?
Aerobic respiration yields 18 times more
energy!!! (36:2)
Man vs. Machine
Another interesting tidbit:
Roughly 45% of the available energy
of a glucose molecule is stored as
ATP following aerobic respiration.
In comparison only 20% of the
energy of gasoline is used by cars.
What happens if we don’t have
oxygen?
Why do we need oxygen?
Aerobic respiration can’t
occur without it.
Without oxygen, the Kreb’s cycle will
stop, leaving a buildup of pyruvic
acid…
The fate of pyruvic acid.
Without oxygen, what are 2 things
that could happen to pyruvic acid?
Alcoholic or lactic fermentation!
What happens to us?
Lactic acid fermentation!
Oxygen Debt
Anytime your muscles get starved for
oxygen, and lactic acid fermentation
begins, you experience oxygen debt.
Oxygen debt is the amount of oxygen
your body requires to get rid of lactic
acid.
Atkins Heaven
We’ve talked about glucose as the
main source of energy for ATP, but
proteins and fats may be used as well.
Fat produces twice as much energy as
glucose does, but you must be twice as
active to burn a gram of fat…
The end…
Proteins may be used as an energy
source as well, though there is much
controversy as to whether this is good
for the body or not…
Ramifications?