Download Electron Transport Chain - Dr-Manar-KSU

* This process happen in the inner membrane of mitochondria
H6C12O6
Dehydrogenase
H
H
2e
NAD+
+
H
+
H
+
2e
Reduction
O
NADH
O
 The
cellular respiration requires through 3
stages :
1. Glycolysis: Converts Glucose to Pyruvate.
2. Krebs Cycle: Completes the oxidation of
organic molecules.
3. Electron Transport: chain to synthesis ATP.
 Cellular
Respiration generates 38
ATP for each sugar molecule.
By substrate-level phosphorylation
By Oxidative phosphorylation
By substrate-level phosphorylation




1.
2.
It occurs in the cytoplasm with the absence of O2
During this stage the Glucose will split into 2
molecules. By oxidizing these 2 molecules they form
2 molecules of Pyruvate.
Each step in this stage is catalyzed by a specific
enzyme
The steps are divided to 2 phases:
Energy investment phase ( requires 2 ATP ) by
Phosphorylation
Energy payoff phase ( produces ATP ) by substratelevel phosphorylation and NAD is reduced to NADH
 Thus,
Glycolysis produces 2 ATP and 2 NADH
and 2 Pyruvate molecules per glucose.
 The terminal phosphate changes the
shape of the molecule to work. When
Transport e.g. membrane protein
the phosphate group leaves the molecule,
the molecule returns to its alternate shape. Chemical e.g. forming products
from reactants.
• An animal cell regenerates ATP from ADP Mechanical e.g. motor protein
and Pi by the catabolism of organic
molecules.
•
The transfer of the terminal phosphate
group from ATP to another molecule is
phosphorylation
These reactions release energy when electrons move closer to
electronegativity atoms like Oxygen. They require both donor and receptor.
The loss of electrons.
Done by reducting agent
The addition of electrons.
Done by oxidizing agent
Na + Cl
Na+ + Cl-
Here sodium is oxidized and chlorine is
reduced . the electron donor, is the reducing
agent while the electron recipient, is the
oxidizing agent.
No CO2 is produced ( in the absence of O2)
Energy investment phase
ADP
ATP
ATP
+
+
Glucose
ADP
2 pyruvates
Energy payoff phase
ADP
4P
ADP
ADP
ATP
ATP
ATP
ATP
ADP
NAD+
NAD+
reduction
NADH
NADH
Net yield:
2 Pyruvates
2 NADH
2 ATP
It occurs mainly in the mitochondrial matrix and
includes 2 cycles:
1. PRE-Krebs cycle: The Pyruvate molecule is
converted to Acetyl-coA in the presence of the
Oxygen.
2. Krebs cycle: Each pyruvate molecule provides 1
ATP by substrate-level phosphorylation 3 NADH
and 1 FADH2
 Thus, the outcome from 2 pyruvate molecules
would be:
 2 ATP
 6 NADH
 2 FADH2

+
1
CO2
Oxidized
ee- +
2
CoA
3
CO2
NAD+
NADH
NAD+
NADH
Acetyl-CoA
Acetyl-CoA
Acetyl-CoA
1
Acetyl-CoA
2
Citrat
e
+
Citrat
e
4C
4C
2CO2
Citrat
e
6
2
NADH
FADH2
ATP
ATP
Citrat
e
 The
majority of the ATP come from the
energy in the electrons NADH and FADH2
these electrons power the ATP synthesis.
 These chains of electron transport are found
in the surface of the cristae in the inner
membrane of the mitochondria.
What
happens to the electrons from
NADH and FADH ?
 They
are ultimately passed to Oxygen to
form water.
1
6
NADH
2
FADH2
Net yield:
34 ATP
Electron
Transport
Chain
2
3
H
H
+
+
H
H
ADP
+
+
Chemiosmosis
ATPSynthase
+P
H
ATP
Intermembrane
space
Inner membrane
H
Matrix
+
+
H
H
+
+

Glycolysis + Krebs cycle + oxidative phosphorylation
2 ATP
+ 2 ATP
+ 34 ATP

= 38 ATP

Glycolysis
By substrate-level phosphorylation
•Happens in the cytoplasm
•Net yield: 2 pyruvates, 2 NADH & 2 ATP
Krebs Cycle By substrate-level phosphorylation
•Happens in the matrix
•Net yield: 6 NADH, 2 FADH2 & 2 ATP
Electron transport
By Oxidative Phosphorylation
•Happens in the inner membrane of the mitochondria
•Net yield: 34 ATP
38 ATP
 complete degradation
 needs O2
Food+O2
 Partial degradation
 Doesn’t need O2
H2O + CO2 + Energy
heat
work
Less
energy
Rich in
energy
Organic
molecules
Degradation
(by enzymes)
simpler
molecules
• In alcohol fermentation, pyruvate is converted to ethanol in
two steps.
– First, pyruvate is converted to a two-carbon compound,
acetaldehyde by the removal of CO2.
– Second, acetaldehyde is reduced by NADH to ethanol.
– Alcohol fermentation
by yeast is used in
brewing and
winemaking.
• During lactic acid fermentation, pyruvate is reduced directly
by NADH to form lactate (ionized form of lactic acid).
– Lactic acid fermentation by some fungi and bacteria is used
to make cheese and yogurt.
– Muscle cells switch from aerobic respiration to lactic acid
fermentation to generate ATP when O2 is scarce.
• The waste product,
lactate, may cause
muscle fatigue, but
it is converted back to
pyruvate in the liver.
Play video
Cellular Respiration (Electron Transport Chain)
http://www.youtube.com/watch?v=xbJ0nbzt5Kw
Electron Transport Chain Animation Overview Chemiosmosis HQ
http://www.youtube.com/watch?v=kN5MtqAB_Yc
 PLZ
OPEN THE VIDEO
Oxidative Phosphorylation
http://www.youtube.com/watch?v=ajZajFrCjtA
Play video

Q1: Write whether each of the following statements is True (T) or False
(F):

1-Accumalation of lactic acid in human is due to alcohol fermentation.

2-Glycolysis is a catabolic process that occurs in the
mitochondria,however Krebs cycle occurs in the cytoplasm.
3-Cytochromes are proteins that function as electron carriers in the
mitochondria.

4-the net yield of ATP by substrate level phosphorylation during citric
acid cycle for each glucose molecule is two.
5- FADH2 is an electron carrier in glycolysis.




6- When O2 is scarce (very few), human muscles produce ATP by lactic
acid fermentation.
7- Carbohydrates are the only fuel used to produce ATP by cellular
respiration.



Q 2: Choose the correct answer (one answer only):
Which molecule is one of the ATP constituents;
a-Adenosine.

b-Cholesterol.

c-The amino acid Tryptophan.

2-During formation of Acetyl CoA;-

a-2NADH molecules are produced.

b-3NADH molecules are produced.

c-2ATP molecules are produced.


3-Which process in eukaryotic cell will normally proceed whether O2 is present or absent;-

a-Glycolysis.

b-kreb cycle.

c-Electron transport system.

4-Complete oxidation of one molecule of glucose will produce ------molecules of ATP;-

a-32.

b-34.

c-38.

5-No ATP produced by substrate level phosphorylation during ;-

a-Glycolysis.

b-Citric acid cycle.

6-Cellular respiration is a catabolic process that transfers hydrogen from;-

a-Sugar to water.

b-Sugar to oxygen.

c-Oxygen to sugar.

7- The oxidizing agent of glycolysis is:

a- NAD+.

b- O2 .

c- NADH.

d-FADH2.


8- Chemiosmosis is the process of generating ATP at:
a- The inner membrane of mitochondria.

b- Mitochondrial matrix.

c- The outer membrane of mitochondria.

d-Cell cytoplasm.

9- Each NADH, that transfers H from food to the electron transport chain
generates:

a- 2 ATP .

b- 3 ATP.

c- 4 ATP.

10- Which of the following compounds is considered as the fuel of the Krebs cycle?

a) - acetyl coA