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)  A) Once, one B) twice, two C) three times, three D) six times, six

BAs 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 decarboxy-lated 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 part-

Technically 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 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 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. B) water. C) NAD+. D) pyruvate. E) ADP.

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+ ATP Summary

64 H+ 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.

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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