Chapter 9

Question 1

Cell Respiration (CR)

Answer 1

Series of metabolic pathways used to break down organic molecules ( ex. carbs)

Converts stored energy from organic molecules (often glucose) into the energy of ATP

Aerobic respiration- respiration in the presence of oxygen

Anaerobic respiration- respiration without oxygen present

Question 2

CR purpose

Learn the Chemical equation and its meanings

Answer 2

1.CR releases a high amount of free energy

2.This energy is very capable of doing work

3.Main function is to synthesize ATP

C₆H₁₂O₆+6O₂—->6CO₂+6H₂O+ATP

Question 3

Redox reaction

Answer 3

1.This reaction is also a redox reaction

2. Glucose is oxidized to CO₂
3. O₂ is reduced to H₂O

Glucose * Oxygen —> Carbon

Question 4

ATP production method 1 Glucose and enzymes

Answer 4

1.Pⁱ comes together with ADP using

2.Hydrolysis of an organic molecules proves the
phosphate and free energy needed

3.Effective but not efficient

4. Only 12% of ATP generated in CR using Glucose

C₆H₁₂O₆+6O₂—->6CO₂+6H₂O+ATP

Question 5

ATP production method 2 Electron carriers

Answer 5

2nd method uses electron carriers NADH and FADH₂

Carry electrons, and hence energy to drive ATP production

Provides 88% of ATP, much more efficient

2nd method is better if resources are not an issue

Question 6

Almost all living things carry our CR

Where do bacteria carry out CR?

Answer 6

Animals, plants, algae, bacteria, etc. Carry out CR

Eukaryotic organisms (including plants) have the mitochondria to carry out CR

in the cytoplasm and at the plasma membrane

Question 7

4 steps of cell respiration

Answer 7

Glycolysis

Pyruvate oxidation

Citric Acid Cycle
(Krebs Cycle)

Oxidative phosphorylation

Question 8

Glycolysis Stage 1

Answer 8

1. 1st stage of cell respiration

2.Glucose is partially broken down to produce pyruvate

3. Takes place in the cytoplasm (only stage outside of mitochondria)

4.Energy is transferred to ATP by substrate-level phosphorylation

Question 9

Pyruvate oxidation Stage 2

Answer 9

1.Pyruvate is oxidized to acetyl-coenzyme or acetyl coA

2.Produces reduced (electron gained) electron carriers

Question 10

Krebs Cycle Stage 3

Answer 10

1.Also called the citric acid cycle

2.Series of redox reactions, acetyl group is oxidized to carbon dioxide

3.Free energy from this is transferred to ATP

4.Energy transferred at this stage is the highest

Question 11

Oxidative phosphorylation Stage 4

Answer 11

1.Reduced electron carriers from 1-3 donate electrons to respiratory electron transport (ETC).

2.This stage generates a large amount of ATP

ETC - made of proteins and molecules from the mitochondrial membrane

Question 12

Storage of glucose

Answer 12

1) Glucose takes time to break down, can quickly buildup in excess

2) 2 storage forms

Glycogen (animal)
Starch (plants)

Question 13

Other macromolecules

Answer 13

1)Proteins and fatty acids can be used as a last resort to power the cell

2)Proteins are broken down into amino acids, than go through stages 1-3 of CR

3)Rarely used due to their structural and functional importance

Question 14

Focus is on the first 3 stages

Answer 14

Glycolysis

Pyruvate oxidation

Krebs or Citric acid cycle

The stages together oxidize glucose into CO₂

Produce a small amount of ATP, but not as much as 4th stage alone

Question 15

Glycolysis part of a metabolic pathway

Answer 15

Is anaerobic because oxygen is not consumed

Considered to be very adaptable, when no oxygen was available in Earth’s atmosphere

Cost is 2 ATP, you with 4 ATP and 2 NADH

Net gain=2 ATP 2 NADH
2 ATP gained

Question 16

Pyruvate oxidation

Answer 16

Can be oxidized to release even more energy, links glycolysis to the Krebs cycle

First step that takes place in mitochondria

Result= 2CO₂, 2NADP, and 2 acetyl CoA
0 ATP gain

Question 17

Krebs Cycle

Answer 17

Acetyl CoA is the initial substrate of the Krebs cycle

8 steps cycle, starting molecule is regenerated in last step

2 ATP gain, reduced electron carriers, and carbon dioxide

Question 18

Fermentation pathways

Answer 18

1) If oxygen is not present pyruvate oxidation does not take place, pyruvate will build up leading to fermentation

2) Fermentation- process that extracts energy from fuel molecules w/o O(g) or ETC (Electron transport chain)

3) Lactic acid fermentation used in muscles cells and bacteria

Question 19

Ethanol Fermentation

Answer 19

Carried out by plants and fungi

Pyruvate releases CO₂ to form acetaldehyde

Used to make beer, wine, other alcoholic beverages

Used in bread making (CO₂ makes bread rise)

Small amount of alcohol that is produced burns off during baking