Download Cellular Respiration

Cellular Respiration
Cauthers 2007
Energy
What are some types of energy we
use everyday?
Living things require chemical energy
stored within their food to function.
Cellular Respiration
Cells break down food into energy
*some as heat
*some as chemical energy
Occurs in multiple steps called a
biochemical pathway
Each step is regulated by enzymes and
involves the transfer of electrons
Energy
Energy derived from food is not given
off in a great burst…how come?
Our cells would die!!!
Small packets of energy are stored
in high energy bonds of ATP
Bond, Phosphate Bond
ATP = adenosine triphosphate
-stores chemical energy
ATP is made of:
1) 1 Adenine
2) 1 Ribose
3) 3 Phosphates
Let’s look at ATP!!!
ADP
Phosphorylation: ATP transfers a
phosphate group (releases energy) it
becomes ADP (adenosine diphosphate)
ADP structure
Phosphorylation
ATP doesn’t grow on trees does it?
The main source of energy is
GLUCOSE!!!
Energy transfer…
Electrons carry energy
Energy is transferred to carriers
If an atom is oxidized, it loses energy
If an atom is reduced, it gains energy
Electron Carriers…
Two types in cellular respiration:
NAD+ and FAD
Each of these can accept a pair of
electrons and H atoms…
Respiration Types
Aerobic respiration requires O2
Anaerobic resp. does not require O2
Aerobic resp. produces much more energy
Who does what?
Only the unicellular organisms (bacteria
mostly) rely solely on anaerobic resp.
Everything else can do both anaerobic
and aerobic resp.
Glycolysis
*First step of all respiration
*Takes place in the cytoplasm
*Does not require oxygen
*Glycolysis= splitting of glucose
Lysis - to split
Glyco- refers to glucose
*Requires energy from ATP
Glycolysis
2 ATP molecules split glucose
4 ATP molecules are created
when pyruvic acid is formed.
How much net ATP is made
through glycolysis?
2 NET ATP
Glycolysis Graphic
Glucose
2ATP
2ADP
2ADP
PGAL
2ADP
2ATP
2ATP
PGAL
Pyruvic Acid
Anaerobic Respiration
ATP is only made during glycolysis.
Therefore how much ATP do anaerobic
organisms make?
2ATP
Fermentation…
*Any reaction that occurs after
glycolysis in an anaerobic
organism
*2 types:
1) Lactic acid fermentation
2) Alcoholic fermentation
Lactic Acid Fermentation
Pyruvic acid is converted to lactic acid.
Any athletes who have felt muscle burn
after a strenuous workout are feeling
lactic acid buildup.
Alcoholic Fermentation
Some organisms (yeast) have enzymes that
break pyruvic acid into ethyl alcohol and
carbon dioxide.
Alcoholic fermentation is important in the
process of… breadmaking!!!!
(CO2 makes bread rise)
Alcohol again…
Alcoholic fermentation also gives rise
to alcohol…
Glucose Source
Beverage
Barley
Beer
Potato
Vodka
Grapes
Rice
Wine
Sake
Aerobic Respiration
How much ATP was produced from
glycolysis in anaerobic respiration?
2 ATP
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…
*Pyruvic acid enters the mitochondrion
*Broken into a 2 carbon molecule
*Forms acetyl CoA
*Enters the Krebs Cycle
Each molecule of pyruvic acid yields
1 CO2 and 1 NADH
Pyruvic Acid
NAD+
NADH
CO2
CoA
Interesting tidbits…
For every turn of the Kreb’s cycle,
only 1 ATP is produced!!!
CO2 is given off
Where does the rest of
the ATP come from?
Electron Transport Chain
Energy stored in NADH and FADH2 is
released in steps
Electrons passed from carrier to carrier,
until O2 accepts the last 2 electrons.
Ahhh, big words…
As e- pass
energy passes
Some of that energy is used to convert
ADP to ATP (by means of a H+ pump)
The last step…
*O2 is the final electron acceptor
*Combines with 4 H, to form…
WATER!!!
2 NET ATP from glycolysis
2 ATP from the Kreb’s
32 from the ETC
36 ATP gained!!!
Net Reactions of aerobic:
C6H12O6 + 6 H2O + 6 O2
6 CO2 + 12 H2O + 36 ATP
Aerobic Pathway
Aerobic Pathway
Recap:
Why aerobic respiration instead of
anaerobic?
Aerobic respiration yields 18 times more
energy!!! (36:2)
What if we don’t have 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
Glucose is 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…
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…and it is terribly
inefficient.
Ramifications? Kidney problems
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.