Transcript Krebs Intro and CycleON

Oh where, Oh where
has 34molecules of ATP
gone????????
Only the Krebs cycle knows for
sure.
The energy produced from the "burning" of glucose is used to make
ATP. In chemistry this process is called the oxidation of glucose.
The purpose of cellular respiration is to make ATP. All cells use and
need ATP.
There are 3 parts to cellular respiration
3 Part of Respiration
I. Glycolysis
II. Kreb's Cycle or Citric Acid Cycle
III. Electron Transport Chain
After glycolysis, pyruvic acid is shuttled to the mitochondrion to
extract the energy from this molecule and convert it to ATP. This is
done by stripping the remaining hydrogens from pyruvic acid or
pyruvate. There are two molecules of pyruvic acid so the Kreb's
cycle occurs twice. The hydrogens are used to reduce NAD and
FAD. In addition 3 molecules of carbon dioxide are released. The
Kreb’s cycle is located in the inner compartment of the
mitochondrion.
Where does the Kreb’s cycle occur?
A) The outer compartment of the mitochondrion
B) The inner compartment of the mitochondrion
C) The cytoplasm
D) The inner compartment of the thylakoid
E) In the stroma
B
The Kreb’s cycle occurs in the inner compartment of the
mitochondrion.
Summary of Krebs or citric acid cycle- Occurs in
mitochondrion
2X’s
Pyruvate---> 3 CO2
6 CO2
1 ADP ---> 1 ATP
2 ATP
4 NAD ---> 4 NADH2
8 NADH2
1 FAD ---> 1 FADH2
2 FADH2
The hydrogen found on pyruvate will be used to
reduce NAD and FAD. Only one ADP is
phosphorylated at the substrate level or directly
by enzymes.
As
As a result of glycolysis, the Kreb’s cycle or
citric acid cycle can be “run” ________ because there
are _____ molecules of pyruvic acid or pyruvate.
A)
three
A) Once, one B) twice, two
D) six times, six
C) three times,
B
As a result of glycolysis, the Kreb’s cycle or citric
acid cycle can be “run”twice because there are two
molecules of pyruvic acid. In glycolysis, there is
glucose, a hexose, is decomposed to make two trioses.
These trioses are oxidized to make two molecules of
pyruvic acid.
Step 1
Prepping step. Pyruvate is decarboxylated and also oxidized. The hydrogens are
used to reduced NAD. Technically not a
part of the Kreb’s cycle
Step 2
The acetyl group is attached to
oxaloacetic acid to form citric acid
As
Cells do not catabolize carbon dioxide because
A)
A) its double bonds are too stable to be broken.
B) CO2 has fewer bonding electrons than other organic
compounds.
C) C) CO2 is already completely reduced.
D)
D) CO2 is already completely oxidized.
E) E) The molecule has too few atoms.
As
D
CO2
CO2 is already completely oxidized as it does
not contain any hydrogen.
This is pyruvate or pyruvic acid. What will happen to this
molecule during the process of the Kreb’s cycle?
A) The oxygens will be stripped off and form oxygen gas.
B) The hydrogens will be stripped off to reduce hydrogen
carriers.
C) It is pick up hydrogens to form monosaccharides.
D) It will be reduced as it picks up oxygen.
B
The hydrogens will be stripped off to reduce hydrogen
carriers and carbon dioxide is released.
Prepping partTechnically not an official step of the Kreb’s cycle
In the “prepping” step of the Kreb’s cycle, pyruvate is
converted to
A) acetyl-Co-A
B) NADH
C) ATP
D) CO2
A
In the “prepping” step of the Kreb’s cycle, pyruvate is
converted to acetyl-Co-A
Step 2
Technically not an official step of the Kreb’s cycle or citric acid cycle
Step 3
Water is removed and then added back
in to make isocitric acid
Step 4
Isocitric acid will be oxidized and NAD
will be-come reduced. The new acid is
oxalosuccinic acid
Steps 3 and 4
Citric acid is isomerized to make isocitric acid and then isocitric acid
is oxidized making oxaloacetic acid. This step reduces NAD
Step 5 Oxalosuccinic acid will be
decarboxylated as it is converted
to a-ketoglutaric acid. It now has
only 5 carbons. Second CO2 is
released.
Step 6 a-ketoglutaric acid will
be decarboxylated and at the
same time oxidized. NAD will
be reduced. Third CO2 is
released.
Step 5 Oxalosuccinic acid will be decarboxylated as it is
converted to a-ketoglutaric acid. It now has only 5 carbons.
Second CO2 is released.
Step 6 a-ketoglutaric acid will be decarboxylated and at the
same time oxidized. NAD will be reduced. Third CO2 is
released.
Step 7. The next step is rather
complicated. Succinyl-Co-A looses the
coenzyme Co-A and is hydrated.
Phosphate is added to GDP--->GTP
which in turns takes the phosphate and
gives it to ADP--->ATP.
Step 8. Succinic acid becomes
oxidized and FAD becomes
reduced.
Step 7. The next step is rather complicated. Succinyl-Co-A looses
the coenzyme Co-A and is hydrated. Phosphate is added to
GDP--->GTP which in turns takes the phosphate and gives it to
ADP--->ATP. This is known as substrate phosphorylation.
Step 8. Succinic acid becomes oxidized and FAD becomes reduced.
Step 9. Fumaric acid
becomes hydrated as water
is added to it.
Step 10.
The last step malic acid is
oxidized and and NAD is reduced
to return to oxaloacetic acid and
start the cycle again
Step 9. Fumaric acid becomes hydrated as water is added to it.
Step 10. The last step malic acid is oxidized and and NAD is reduced
to return to oxaloacetic acid and start the cycle again
Most CO2 from catabolism is released during
A) glycolysis.
B) the citric acid cycle.
C) lactate fermentation.
D) electron transport.
E) oxidative phosphorylation.
B
Most CO2 from catabolism is released during the citric acid
cycle or Kreb’s cycle. If anaerobic respiration is
occurring, CO2 can be released from alcoholic
fermentation.
Summary of Krebs or citric acid cycle- Occurs in
mitochondrion
2X’s
Pyruvate---> 3 CO2
6 CO2
1 ADP ---> 1 ATP
2 ATP
4 NAD ---> 4 NADH2
8 NADH2
1 FAD ---> 1 FADH2
2 FADH2
The hydrogen found on pyruvate will be used to
reduce NAD and FAD. Only one ADP is
phosphorylated at the substrate level or directly
by enzymes.
Which of the following is false?
A) The intermediates of the Kreb’s cycle can be used in
other biochemical pathways.
B) Each step of the citric acid requires an enzyme.
C) The Kreb’s cycle occurs in the outer compartment of the
mitochodrion
D) The main purpose of the Kreb’s cycle is to reduce NAD
and FAD with hydrogens from acetyl-Co-A
C
The Kreb’s cycle occurs in the inner compartment of the
mitochondrion. All the other statements are true.
The purpose of chemiosmosis is to extract the energy found in
NADH and FADH2 to make more ATP. This involves the cristae.
There are electron transport chains that are used.
The electrons from the NADH and FADH2 are used to move on the
electron transport chain. As the electrons move down the electron
transport chain, H+ ions are pumped across the membrane.
The electrons from one NADH can pump 6 H+ across the membrane,
but the electrons from FADH2 can only pump 4 H+ across the
membrane.
The final acceptor of the electron is oxygen. Oxygen becomes
reduced as it accepts the electron and bonds with H+ to form water.
Without oxygen, the electron transport chain shuts down and the
Kreb’s cycle shuts down causing fermentation to take over.
The final electron acceptor of the electron transport chain
that functions in oxidative phosphorylation is
A) oxygen.
E) ADP.
B) water.
C) NAD+.
D) pyruvate.
A
The final electron acceptor of the electron transport chain
that functions in oxidative phosphorylation is oxygen.
Oxygen accepts the electron and hydrogen ions to form
water. Without oxygen, the Kreb’s cycle and oxidative
phosphorylation would not occur.
The outer compartment of the
mitochondria becomes positive and
the inside becomes negative like a
battery. This "battery" can do work.
The hydrogen ions can cross an F1
particle and make ATP.
It takes 2 H+ to cross the F1 particle to
provide enough energy to make ATP.
Because the electron transport chain
oxidizes NADH or FADH2 and uses
the energy to phosphorylate ADP, this
is also known as oxidative
phosphorylation.
In the presence of a metabolic poison that specifically and
completely inhibits all function of mitochondrial ATP
synthase, which of the following would you expect? The
Kreb’s cycle occurs in the inner compartment of the
mitochondrion. All the other statements are true.
A) a decrease in the pH difference across the inner
mitochondrial membrane
B) an increase in the pH difference across the inner
mitochondrial membrane
C) increased synthesis of ATP
D) increased oxygen consumption
E) an accumulation of NAD+
B
The electron transport chain would continue to function and
H+ would continue to be pumped into the inner compartment
of the mitochondrion. This would decrease the pH in inner
compartment of the mitochondrion.
The immediate energy source that drives ATP synthesis by
ATP synthase during oxidative phosphorylation is
A) the oxidation of glucose and other organic compounds.
B) the flow of electrons down the electron transport chain.
C) the affinity of oxygen for electrons.
D) the H+ concentration gradient across the inner
mitochondrial membrane.
E) the transfer of phosphate to ADP.
D
The immediate energy source that drives ATP synthesis by
ATP synthase during oxidative phosphorylation is the H+
concentration gradient across the inner mitochondrial
membrane. This is like a battery. The inner compartment
is negative and the outer compartment is positive. The
charge across the membrane can be used to do work.
8 NADH2 x 6 H
= 48 H+
2 FADH2(Krebs)x 4 H = 8 H+
2 FADH2(glyc.) X 4 H = 8 H+
64 H+
ATP Summary
64 H+ --> 32 ATP
The immediate energy source that drives ATP synthesis by
ATP synthase during oxidative phosphorylation is
A) the oxidation of glucose and other organic compounds.
B) the flow of electrons down the electron transport chain.
C) the affinity of oxygen for electrons.
D) the H+ concentration gradient across the inner
mitochondrial membrane.
E) the transfer of phosphate to ADP.
A
The pH of the matrix increases as H+ ions are pumped out.
This makes the outer compartment acidic and the inner
compartment alkaline.
Play Animation
Fast Speed
Play Animation
Medium Speed
Play Animation
Slow Speed
ATP can be made from other foods other than glucose.
I. Carbohydrates
a. Starch--> X's glucose molecules and now respired in
glycolysis
b. Sucrose--> glucose and fructose and now respired in
glycolysis
II. Fats/Lipids-> Glycerol and 3 fatty acids
Glycerol is converted to PGAL and respired in glycolysis.
The fatty acids are chopped into 2 carbon acetyl groups and
used in the Krebs or citric acid cycle.
Which of the following is true?
A) Proteins can be used in cellular respriation provided that
they are not digested.
B) Starch cannot be used in cellular respiration because
there are no digestive enzymes to break the starch down
C) Lipids can be use in cellular respiration once the
hydrocarbon tails are broken down to acetyl groups
D) Amino acids can be used in cellular respiration once they
are reassembled into proteins
D
Lipids can be use in cellular respiration once the
hydrocarbon tails are broken down to acetyl groups.
Starch can be used in cellular respiration once it is
digested down to monosaccharide, glucose.
III. Proteins--> amino acids
Once the amino acids are
produced, then the
amine group must be
removed. The left over
acid is then used at some
point in the Krebs cycle