Transcript CH 2. CELLULAR RESPIRATION

CH 2. CELLULAR RESPIRATION
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CH 2. CELLULAR RESPIRATION
Cellular respiration is the
process whereby the body
converts the energy that we get
from food (glucose) into an
energy form that the body can
use – ATP!
FOOD =
GLUCOSE
ATP!!!!!!
CH 2. CELLULAR RESPIRATION
• There are 2 major types of cellular
respiration…
» 1. AEROBIC
CELLULAR
RESPIRATION
ANAEROBIC CELLULAR
RESPIRATION
» 2.
The big difference is
oxygen!!!!!
CH 2. CELLULAR RESPIRATION
• There are 2 major types of cellular
respiration…
»
AEROBIC CELLULAR RESPIRATION
» Uses oxygen and produces MORE energy!
»
ANAEROBIC CELLULAR
RESPIRATION
» Does NOT use oxygen, produces LESS energy but much
faster!
CH 2. CELLULAR RESPIRATION
•
AEROBIC CELLULAR
RESPIRATION – includes anaerobic cellular
respiration plus 3 extra steps.
• Overall, there are 4 stages to cellular respiration:
–
1. GLYCOLYSIS – a 10 step process occurring in the cytoplasm
–
2. PYRUVATE OXIDATION – a one-step process in the
mitochondrial matrix
–
3. THE KREBS CYCLE – an 8 step cyclical process occurring in
the mitochondrial matrix
–
4. ELECTRON TRANSPORT CHAIN – a multistep process
occurring in the mitochondrial membrane
CH 2. CELLULAR RESPIRATION
• The overall chemical equation for cellular
respiration is as follows:
C6H12O6(aq) + 6O2(g)   6CO2(g) + 6H2O(l) + 36 ATP
glucose
oxygen
Carbon
dioxide
water
ENERGY!
In other words, the combustion of one molecule of glucose yields 36 molecules
of ATP along with carbon dioxide and water as by-products.
Since the activation energy needed for the combustion of glucose is quite high,
each step in cellular respiration is catalyzed by specific
enzymes that lower the activation energies and allow the reactions to occur at a
pace fast enough to maintain cell needs.
CH 2. CELLULAR RESPIRATION
• The 3 overall goals of this process are:
• 1. to break the bonds between the six carbon atoms
of glucose, resulting in 6 carbon dioxide molecules.
• 2. to move hydrogen atom electrons from glucose to
oxygen, forming 6 water molecules.
• 3. to trap as much of the free energy released in the
process as possible in the form of ATP.
C6H12O6(aq) + 6O2(g)   6CO2(g) + 6H2O(l) + 36 ATP
STEP ONE: GLYCOLYSIS
• Glycolysis involves 10 enzymecatalyzed reactions (each step has its own specialized
enzyme!)
• Each reaction of glycolysis occurs in the
cell's cytoplasm
2NADH
2ATP
C6H12O6(aq)
Two 3-C molecules
of pyruvate
STEP ONE: GLYCOLYSIS
• In glycolysis, a total of 2 ATP molecules are
USED in step one and three
• 2 ATP are produced in the 7th step, when
BPG phosphorylates ADP to ATP
• 2 ATP are produced in the 10th step when
PEP phosphorylates ADP to ATP
(-2ATP) + 4ATP =
2ATP
(net yield)
STEP ONE: GLYCOLYSIS
•
http://www.youtube.com/watch?v=O5eMW4b
29rg
STEP TWO: PYRUVATE
OXIDATION
• TIME TO MOVE INTO THE
MITOCHONDRIA!!!!
» the 2 molecules of pyruvate from
glycolysis are transported through the two
mitochondrial membranes into the matrix
» In the matrix, a multi-enzyme complex
catalyzes 3 MAJOR CHANGES!!!!
STEP TWO: PYRUVATE
OXIDATION
1. A low-energy carboxyl group is removed as CO2.
STEP TWO: PYRUVATE
OXIDATION
2. NAD+ is reduced by two H atoms
STEP TWO: PYRUVATE
OXIDATION
3. A sulfur-containing compound called coenzyme A (CoA)
is attached to the remaining acetic acid portion – forming
a molecule called acetyl-CoA
STEP TWO: PYRUVATE
OXIDATION
• The following is the overall equation for
pyruvate oxidation:
2 pyruvate + 2NAD+ + 2CoA   2acetyl-CoA + 2NADH +
2H+ + 2CO2
Acetyl-CoA moves on the
third step! = Krebs Cycle!
NADH skips step three and
moves on to stage four! =
electron transport chain!
WARNING!!!!!!
Acetyl-CoA is a CENTRAL
MOLECULE IN ENERGY
MOTABOLISM!!!!!
ALL molecules that are catabolized for energy are converted
into acetyl-CoA – including proteins, lipids and
carbohydrates!
acetyl-CoA is MULTIFUNCTIONAL – it can be used to
produce fat or ATP
 if the body needs energy, acetyl-CoA will enter the
KREBS CYCLE and transfer its free energy into ATP
 if the body does not need energy, acetyl-CoA is
channelled into an anabolic pathway that synthesizes lipids.
STEP THREE: KREBS CYCLE
• The Krebs Cycle is an 8-step process!!!!
» each step is catalyzed by its own enzyme
• It is a cyclic process!
• the product of step 8 (oxaloacetate) is the
reactant in step 1!!!!!
The Krebs Cycle is a cyclic
series of reactions that
transfers energy from organic
molecules to ATP, NADH,
and FADH2 and removes
carbon atoms as CO2.
STEP THREE: KREBS CYCLE
•
http://www.youtube.com/watch?v=WcRm3MB
3OKw
STEP THREE: KREBS CYCLE
• By the end of the Krebs cycle, the original
glucose molecule is entirely consumed!
» the 6 carbon atoms leave as low energy CO2
molecules
The Krebs Cycle produces:
- 2 molecules of CO2
- 3 NADH
- 1 ATP
- 1 FADH2
X2
Because there
are 2 acetyl-CoA
molecules that go
through
The Krebs Cycle produces:
- 4 molecules of CO2
- 6 NADH
- 2 ATP
- 2 FADH2
Energy is harvested in steps
3,4,5,6 & 8 :
-In steps 3, 4 and 8  NAD+ is
reduced to NADH
- In step 5  ATP is formed by
phosphorylation
The reduced coenzymes now go on to stage
4  ELECTRON TRANSPORT CHAIN
- In step 6  FAD is reduced to
FADH2
STEP FOUR: ELECTRON
TRANSPORT CHAIN
• http://www.youtube.com/watch?v=_PgjsfY71A
M
• http://www.youtube.com/watch?v=xbJ0nbzt5K
w&feature=related
• http://www.youtube.com/watch?v=3y1dO4nNa
KY&feature=related
• http://www.youtube.com/watch?v=RpL6wsixZ4
• http://www.youtube.com/watch?v=kN5MtqAB_
Yc&NR=1
STEP FOUR: ELECTRON
TRANSPORT CHAIN
• each NADH molecule results in 3 ATP
molecules
• each FADH2 molecule results in 2 ATP
molecules
ENERGY TOTALS!!!
• review pg. 110 – figure 25
• Review pg. 114 – table 3