Ch. 9 Cellular Respiration

Question 1

What is the balanced equation for cellular respiration?

Answer 1

C6H12O6+ 6 O2 -> 6 CO2 + 6 H2O+ energy that is used to rebuild ATP from ADP + Pi

Question 2

What is oxidation?

Answer 2

A substance loses electrons or is oxidized

Question 3

What is reduction?

Answer 3

A substance gains electrons or is reduced

Question 4

How are these reactions coupled?

Answer 4

Oxidation is the release of an electron (similar to exergonic)
Reduction is the gain of an electron (similar to endergonic)
A coupled reaction is a reaction that uses energy from an exergonic reaction to fuel an endergonic reaction

Question 5

Understanding H atoms are comprised of one electron and one proton (no neutrons) Part I:

Answer 5

When a molecule loses one hydrogen atom, it loses one electron. Therefore, when a molecule loses H, it gets oxidized

Question 6

Understanding H atoms are comprised of one electron and one proton (no neutrons) Part II:

Answer 6

When a molecule gains one hydrogen atom, it gain one electron. Therefore, when a molecule gains H, it is reduced

Question 7

Hydrogen atoms (H) gains/loss represents electron gain/loss in oxidation/reduction reactions

Answer 7

To track electrons in oxidation/reduction, track hydrogen atoms

Question 8

Glucose is oxidized (CO2 remains), and NAD+ and FAD are reduced (this forms NADH and FADH2)

Answer 8

Takes places during the Glycolysis and the Citric Acid Cycle

Question 9

NADH and FADH2 are oxidized (NAD+ and FAD remains), and O2 is reduced (this forms H2O)

Answer 9

Takes place during Oxidative phosphorylation

Question 10

What are the 3 stages of cellular respiration?

Answer 10

Glycolysis, The Citric Acid Cycle (includes formation of Acetyl-CoA), Oxidative phosphorylation (Electron transport chain and Chemiosmosis)

Question 11

Why is glucose broken down in so many small stages?

Answer 11

The harvesting of energy from glucose by cellular respiration is a cumulative function of three metabolic stages. Is broken down in Glycolysis and then pyruvate oxidation and the Citric Acid Cycle.

Question 12

What is the difference btw aerobic and anaerobic respiration

Answer 12

Aerobic respiration: uses O2

Anaerobic respiration: does NOT use O2

Question 13

Big Picture of Cellular Respiration

Answer 13

Glucose is broken down (exergonic reactions), and potential energy stored in the chemical bonds of glucose is used to rebuild ATP (endergonic reactions)
ADP + Pi + energy = ATP (this is endergonic)

Question 14

Why is ATP continuously rebuilt?

Answer 14

The energy contained in ATP is used to carry out all types of work in the cell

Question 15

Breaking down glucose is exergonic; the rebuilding of ATP is endergonic. What is this an example of?

Answer 15

Reactions are coupled

Question 16

What stage is ATP produced in?

Answer 16

Glycolysis, Citric Acid Cycle, Electron Transport Chain (Oxidative Phosphorylation).
Mostly produced in the Oxidative Phosphorylation

Question 17

What stages is NADH produced in?

Answer 17

Glycolysis, Citric Acid Cycle, Mostly produced in Citric Acid Cycle

Question 18

What stages is FADH2 produced in?

Answer 18

Citric Acid Cycle, Mostly produced here

Question 19

What stages is CO2 produced in?

Answer 19

Citric Acid Cycle, mostly produced here too

Question 20

What stage is H2O produced in?

Answer 20

Oxidative Phosphorylation (Electron Transport Chain). Mostly produced here

Question 21

What occurs during the glycolysis stage?

Answer 21

A type of anaerobic respiration where it breaks down glucose, splits glucose into two molecules of pyruvate

Net energy yield: 2 Pyruvates + 2H2O, 2ATP and 2NADH + 2H+(takes place in the cytosol)

Question 22

What is the product that is produced? This product proceeds to the next stage.

Answer 22

Pyruvate yields 3 CO2 (carbon dioxide) molecules that is converted to Acetyl CoA which later joins the Citric Acid Cycle

Question 23

Glycolysis is the only stage of cellular respiration with an energy investment phase. What/how much ‘energy’ is input in this phase?

Answer 23

Spends 2 ATP

Question 24

Does glycolysis require the presence of oxygen? (Is this stage aerobic or anaerobic?)

Answer 24

No, this stage is anaerobic

Question 25

Where in the cell does glycolysis take place?

Answer 25

The cytosol (cytoplasm)

Question 26

At the end of glycolysis, will cellular respiration always proceed (continue)? Or will fermentation proceed? Explain.

Answer 26

If oxygen is present then it proceeds to cellular respiration and if no oxygen is present then fermentation will occur

Question 27

What is the mini step that occurs at the beginning of the stage 2 (citric acid cycle):

Answer 27

Pyruvate is converted to acetyl-CoA

Question 28

What occurs during the Acetyl-CoA conversion?

Answer 28

1. Pyruvate is oxidized and gives off a molecule of CO2 2. Remaining 2-carbon fragment is oxidized and the electrons transferred to NAD+, storing energy in a form of NADH 3. coenzyme A (CoA), is attached via it’s surfer atom to the 2-carbon intermediate, forming Acetyl CoA

Question 29

What molecule does Acetyl-CoA join to begin the citric acid cycle?

Answer 29

Oxaloacetate

Question 30

What is the first molecule produced in the Citric Acid Cycle?

Answer 30

Citrate

Question 31

What molecule is regenerated at the end of the Citric Acid Cycle?

Answer 31

Oxaloacetate

Question 32

How many turns of the Citric Acid Cycle take place during the breakdown of 1 molecule of glucose?

Answer 32

Twice because there are 2 pyruvates

Question 33

Where in the cell does the citric acid cycle take place? BE SPECIFIC.

Answer 33

The Mitochondrion, in the mitochondrial matrix

Question 34

What kind of molecules comprise the electron transport chain?

Answer 34

Most components of the chain are proteins

Question 35

What molecules provide (the H atoms which provide) the electrons which travel through the electron transport chain? Be specific

Answer 35

NADH and FADH2; each donate an equivalent number of electrons (2) for oxygen reduction.

Question 36

What happens to the electrons during their trip through electron transport chain?

Answer 36

Electrons drop in free energy as they go down the chain, releasing energy to drive chemiosmosis

Question 37

What molecule is the final electron acceptor in Electron transport chain?

Answer 37

Oxygen (O2)

Question 38

What happens to the energy given off by the transfer of electrons (oxidation-reduction reactions) during the electron transfer chain? It does NOT go to building ATP.

Answer 38

It drives chemiosmosis

Question 39

Where in the cell does the electron transport chain take place? BE SPECIFIC.

Answer 39

Inner mitochondrial membrane/ inner membrane of the mitochondrian

Question 40

What molecules provide (the H atoms which provide) the protons, which undergo chemiosmosis? Be specific

Answer 40

NADH and FADH2

Question 41

What happens to the protons in Chemiosmosis? Where in the cell does this take place? BE SPECIFIC.

Answer 41

The protons are pumped out of the matrix/ released into surrounding solution

Question 42

Proton-motive force

Answer 42

The potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ions (H+) across a biological membrane during chemiosmosis

Question 43

What directly (immediately) supplies the energy needed to fuel Chemiosmosis?

Answer 43

The Electron Transport Chain

Question 44

What is the role of ATP synthase?

Answer 44

It harnesses the proton-motive force to phosphorylate ADP, forming ATP

Question 45

What generates the energy to fuel the formation of ATP from ADP + P?

Answer 45

Proton gradient across the membrane/ the proton motive force

Question 46

What role does oxygen play? (Know the specific details of its role; why is it necessary to breath?)

Answer 46

Oxygen is used as the end electron acceptor for the electron transport chain. Allows electrons to be transferred through the electron transport chain in order to create an electrochemical gradient for hydrogen to create ATP

Question 47

In what stage(s) of cellular respiration does oxygen play a role?

Answer 47

Pyruvate oxidation, citric acid cycle and oxidative phosphorylation

Question 48

How is water formed at the end of cellular respiration? BE SPECIFIC.

Answer 48

Each O (oxygen) picks up a pair of hydrogen ions (protons) from the aqueous solution, neutralizing the -2 charge of the added electrons and forming water

Question 49

What molecule is reduced to form water?

Answer 49

Oxygen (goes from O2 to O)