Chaper 9

Question 1

Define cellular respiration. What does it require? What does it produce?

Answer 1

Cellular Respiration converts the chemical energy off food molecules into chemical energy of ATP.
It requires oxygen.
It produces ATP.

Question 2

Describe how energy flows through a system.

Answer 2

Energy Flows through a system by:
Solar energy —-> chemical energy of food —>chemical energy of ATP—-> heat

Question 3

Describe how nutrients cycle through a system.

Answer 3

The products of photosynthesis are the reactants of cellular respiration, and vice versa. Nutrients cycle through a system by cellular respiration and photosynthesis.

Question 4

Define photosynthesis and cellular respirations/fermentation in terms of energy.

Answer 4

Photosynthesis is the energy acquisition (light energy —> chemical bond energy)
Cellular respiration/fermentation is energy release (chemical bond energy —-> ATP +heat)

Question 5

Through what process in glucose used to make ATP in aerobic environments? What process is used in anaerobic environments?

Answer 5

Aerobic environment glucose is used in cellular respiration.

Anaerobic environment glucose is used in fermentation.

Question 6

Carbon atoms of glucose are _____ (reduced/oxidized) to form what byproduct?

Answer 6

oxidized, to form CO2

Question 7

Oxygen atoms in oxygen are ______ (reduced/oxidized) to form what byproduct?

Answer 7

Reduced, to form H2O

Question 8

Write out the chemical formula for cellular respiration.

Answer 8

C6H12O6 +6 O2 —> 6 CO2 + 6 H2O + energy

Question 9

List and describe the four steps of cellular respiration.

Answer 9

1) Glycolysis: glucose is broken down to pyruvate
2) Pyruvate processing: pyruvate is oxidized to form acetyl CoA.
3) Citric Acid Cycle: Acetyl CoA is oxidized to CO2
4) Electron Transport and Chemiosmosis: Compounds reduced in steps 1-3 are oxidized in reactions leading to ATP production.

Question 10

Define what occurs during glycolysis. Where in the cell does glycolysis occur?

Answer 10

Glycolysis breaks glucose (6 carbon) into two pyrrhic acid molecules (3 carbon). Glycolysis occurs in the cytosol.

Question 11

List the products (results) of glycolysis.

Answer 11

2 pyruvate molecules
2 molecules of NAD+ are reduced to form NADH
4 molecules of ATP are formed by substrate level phosphorylation

Question 12

Define substrate-level phosphorylation.

Answer 12

Substrate level phosphorylation occurs when enzymes transfer an inorganic phosphate from a substrate to ADP, forming ATP.

Question 13

Where is pyruvate transported to after being formed in the cytosol?

Answer 13

It is transported to the mitochondria in the presence of O2.

Question 14

Define what occurs during pyruvate processing. Where in the cell does this occur?

Answer 14

2 pyruvates (3C) molecules are oxidized to form 2-acety-CoA (2C) molecules. A NAD+ are reduced to form 2 NADH. 2 CO2 molecules are released as waste.

This occurs in the matrix of the mitochondria.

Question 15

Describe the main process of the citric acid cycle. (Hint: what enters and what exits?)

Answer 15

The acetyl CoA produced in the pyruvate processing enters the citric acid cycle and are oxidized to make 2 molecules of CO2.

Question 16

Where in the cell does the citric acid cycle take place?

Answer 16

Occurs in the mitochondrial matrix.

Question 17

What are the three uses of the released potential energy from the citric acid cycle?

Answer 17

1) reduce NAD+ to NADH
2) Reduce FAD+ to FADH2
3) Phosphorylate GDP/ADP to form ATP (depending on the cell)

Question 18

List the six steps of the citric acid cycle in detail.

Answer 18

1) 2 carbon molecule (acetyl CoA) joins a 4 carbon molecule to form citric acid.
2) 2 CO2 molecules exit as waste
3) Most of energy (from electrons) are captured by NADH
4) Some energy transfers ADP—> ATP
5) Remaining electrons are captured by FADH2
6) Any 4 carbon molecules in citric acid cycle are recycled and join another acetyl CoA forming citric acid.

Question 19

(Not a question, just information)

Answer 19

Glucose oxidation includes three of the four steps of cellular respiration: glycolysis, pyruvate processing, citric acid cycle

Question 20

Glucose oxidation (glycolysis, pyruvate processing, citric acid cycle) produces ATP, NADH, FADH, and CO2. How many of each are produced in total?

Answer 20

4 ATP, 10 NADH, 2 FADH2, 6CO2

Question 21

Where in the mitochondria are the electron transport proteins located?

Answer 21

Located on the cristae (inner membranes of the mitochondria)

Question 22

NAD+ pick up two____ (electron/hydrogen ion) and one ______ (electron/hydrogen ion) from glucose, and becomes reduced to______.

Answer 22

Electrons, hydrogen ion, reduced to NADH

Question 23

What facilitates the transfer of electrons as they lose energy?

Answer 23

The electron transport chain facilitates the transfer of electrons as they lose energy.

Question 24

What is the final result of this transfer of electrons? (Hint: What is the main goal of cellular respiration?)

Answer 24

The transfer of electrons activates electron transport proteins to make ATP.

Question 25

Name the atom at the end of the electron transport chain that is the final electron acceptor.

Answer 25

The final electron acceptor is Oxygen (O2)

Question 26

Explain why electrons are moved from one electron acceptor to the next, in regards to how it affects hydrogen ions (H+).

Answer 26

Electrons move from one electron acceptor to the next to an even lower energy state. Energy isn’t lost but used to fuel a hydrogen ion pump. The hydrogen ions are pumped across the membrane, their potential energy is increased because a steep concentration gradient is created.

Question 27

Explain how the created concentration gradient of hydrogen ions create ATP, including involved enzymes, locations, etc.

Answer 27

The ions flow through the system through the enzyme ATP synthase back to the other side of the membrane. The flow of H+ ions is converted to kinetic energy. The kinetic energy from the hydrogen ion flow allows ATP synthase to make ATP in a process : Chemiosmosis.

Question 28

Define Chemiosmosis.

Answer 28

Chemiosmosis when H+ flows down the Fo unit, the rotor shaft rotates, increasing the affinity of the ADP to Pi to form ATP.

Question 29

What type of phosphorylation occurs in the electron transport chain?

Answer 29

Oxidative phosphorylation

Question 30

What specific membrane protein phosphorylates ADP into ATP?

Answer 30

ATP synthase

Question 31

Where is the majority of ATP from glucose oxidation occur out of the 4 steps of cellular respiration? How many of the 29 ATP are produced in this step?

Answer 31

ATP synthase produces 25 of the 29 ATP molecules.

Question 32

What are the two examples of final electron acceptors prokaryotes use in anaerobic respiration?

Answer 32

NO3 - and SO4 2-

Question 33

What is the downside of using electron acceptors other than oxygen?

Answer 33

They are less electronegative and generate less ATP.

Question 34

Does fermentation (another anaerobic pathway to produce ATP) require oxygen?

Answer 34

No it does not require oxygen.

Question 35

Which stage of cellular respiration is fermentation a modification of?

Answer 35

A modified glycolysis stage.

Question 36

List and describe the two steps of the fermentation process.

Answer 36

Pyruvate —> ethanol or lactic acid
Reduce pyruvate and oxidize NADH to NAD+

Question 37

How many ATP does fermentation produce? Is it more or less efficient compared with cellular respiration?

Answer 37

2 molecules of ATP , less efficient compared to cellular respiration.

Question 38

If oxygen is not available, what is pyruvate reduced into? What is the point of this reduction?

Answer 38

Pyruvate is reduced to lactic acid, the purpose is to regenerate more NAD+

Question 39

What is the downside of creating more electron carriers? (Hint: its a good thing, because it can oxidize more glucose, but too much of a good thing is bad!)

Answer 39

It creates a high concentration of waste products (lactic acid)

Question 40

Describe lactic acid fermentation.

Answer 40

This occurs in human muscle cells, Pyruvate produced by glycolysis accepts electrons (H+) from NADH —> NAD+ and lactic acid is formed.

Question 41

Describe alcohol fermentation.

Answer 41

Occurs in yeast, Pyruvate is converted to acetaldehyde and CO2, Acetaldehyde accepts electrons from NADH —> NAD+ and ethanol are produced.