Stages of Glucose Oxidation

Question 1

3 Stages of oxidation of glucose. Where do they take place.

Answer 1

1. Glycolysis, in the cytosol.
2. The krebs cycle, in the mitochondrial matrix
3. Oxidative phosphorylation, Across the inner mitochondrial membrane.

Question 2

What does glycolysis mean

Answer 2

Splitting of sugar

Question 3

What is glycolysis?

Answer 3

Metabolic pathway comprising of ten reactions.

Question 4

What are the three major results of glycolysis?

Answer 4

1. By the end, each glucose has been split into two molecules of pyruvate.
2. During this process, 2 ATP are used but 4 are produced in substrate level phosphorylation. yielding 2 ATP.
3. Two molecules of NAD+ are reduced yielding two molecules of NADH for every molecule of glucose.

Question 5

Is oxygen consumed and CO2 produced in glycolysis? This means it is ..

Answer 5

No. Anaerobic.

Question 6

Why is glycolysis useful?

Answer 6

Produces some ATP and sets the stage for subsequent events that yield much more ATP.

Question 7

What prevents pyruvate from proceeding through the further stages of glucose oxidation? If this is not avaible, what is pyruvate converted to?

Answer 7

A readily source of oxygen. Lactic acid(lactate) and not broken down further.

Question 8

Aerobic respiration occurs where?

Answer 8

Mitochondrion

Question 9

What is the end result of glycolysis?

Answer 9

2 Pyruvate

Question 10

How many ATP required for glycolysis? What happens to them? What enzyme is active here?

Answer 10

2. converted to ADP and this results in a 6-carbon compound that has 2 phosphate groups. Hexokinase.

Question 11

What happens to the 6-carbon compound during glycolysis?

Answer 11

The 6-carbon compound is split into two 3-carbon compounds. Each of these 3-carbon compounds has one phosphate group.

Question 12

What occurs after the 6 carbon compound is split?

Answer 12

NAD+ pick up electrons and becomes NADH

Question 13

What is the purpose of NADH?

Answer 13

NADH contains energy that can be used to produce ATP

Question 14

After NADH is produced, what occurs?

Answer 14

Additional phosphorylation, creating three carbon groups that have two phosphate groups each.

Question 15

What is hexokinase?

Answer 15

It is an enzyme that acts on 6 carbon atoms. It adds a phosphorus group thus phosphorylizing it.

Question 16

What is happens to the NADH that is produced in glycolysis?

Answer 16

Eventually gives up its electrons.

Question 17

What is the starting point of the krebs cycle?

Answer 17

There is none, because it is a cycle.

Question 18

Glucose oxidation does not proceed beyond glycolysis until?

Answer 18

Pyruvate enters the mitochondrial matrix

Question 19

When does fermentation occur?

Answer 19

If there is no oxygen present for the pyruvate.

Question 20

What are the waste products of fermentation?

Answer 20

Lactate and alcohol.

Question 21

Step 2 of cellular respiration

Answer 21

Formation of Acetyl CoA

Question 22

What is pyruvate converted to, and how?

Answer 22

Acetyl CoA. converted to acetyl CoA by the removal of CO2 and the help of CoA. Pyruvate is a C3, acetyl CoA is a C2

Question 23

During the linking step, what happens to NAD+. Why is it called linking step.

Answer 23

Reduces NAD+ to NADH+H+ links glycolysis to krebs cycle

Question 24

How many acetyl CoA are produced from the initial one glucose molecule

Answer 24

Two.

Question 25

The Acetyl portion become bonded to what in the krebs cycle?

Answer 25

C4 molecule, to produce a C6 molecule. CoA + C4  C6 + Coenzyme A

Question 26

What occurs after it bonds to the c4 molecule. What else occurs at this step?

Answer 26

A Co2 is removed to produce C5 molecule. NADH is also produced from NAD+

Question 27

After the C5 is produced, what happens? In the krebs cycle.

Answer 27

Another CO2 is released, Two more NADH are produced one FADH2 is produced and one ATP which is produced by subtrate level phosphorylation.

Question 28

List the step of the krebs Cycle.

Answer 28

1. Pyruvate (3C) is stripped of carbon, producing acetate (2C) and releasing CO2
2. NAD+ is reduced to NADH
3. Acetate is coupled with coenzyme A to form Acetyl-CoA
4. Acetyl-CoA (2C) combines with oxaloacetate (4C) to form citrate (citric acid) (6C)
5. Citrate is cycled back to oxaloacetate
6. CO2 is released
7. Hydrogen (H+ and e-) is released to carriers NAD+ and FAD to form NADH and FADH2
8. 2 ATP formed

Question 29

Which two molecules from the krebs cycle can be used to form ATP. Production of ATP from these uses what?

Answer 29

NADH and FADH2. The electron transport chain.

Question 30

Electron transport chain occurs where

Answer 30

Inner mitochondrial membrane.

Question 31

Go through electron transport chain. 8.

Answer 31

1. NADH and FADH2 from cellular respiration bring electrons to the electron transport system.
2. When a carrier is reduced, some of the energy that is gained as a result of that reduction is used to pump hydrogen ions across the membrane into the intermembrane space.
3. The electron is then passed to another carrier.
4. As before, some of the energy gained by the next carrier as a result of reduction is used to pump hydrogen ions into the intermembrane space.
5. Eventually, a concentration gradient of hydrogen ions is established in the intermembrane space (green on the diagram).
6. The last carrier must get rid of the electron. It passes it to oxygen to form water (next slide).
7. Two electrons are required to form one molecule of water. The process therefore happens twice for each water molecule.
8. ATP synthase produces ATP by phosphorylating ADP. The energy comes from hydrogen ions forcing their way into the matrix as they pass through the ATP synthase (due to osmotic pressure).

Question 32

Fermentation involves what, plus additional steps?

Answer 32

Glycolysis.

Question 33

Because glycolysis needs NAD+, The NADH that is produced must?

Answer 33

Regenerate to NAD+, otherwise glycolysis will stop.

Question 34

What happens in when lactic acid is produced

Answer 34

NADH gives electrons to pyruvate which is reduced to lactate.

Question 35

How does NAD+ function in cellular respiration?

Answer 35

by carrying two electrons. With two electrons, it becomes NADH

Question 36

What does NAD+ do ?

Answer 36

NAD+ oxidizes its substrate by removing two hydrogen atoms. One of the hydrogen atoms bonds to the NAD+. The electron from the other hydrogen atom remains with the NADH molecule but the proton (H+) is released.
NAD+ + 2H ® NADH + H+
NADH then donate the two electrons (one of them is a hydrogen atom) to another molecule