Chapter 7–Cellular a Respiration and Fermentation

Question 1

What is a redox reaction?

Answer 1

An oxidation-reduction reaction. A chemical reaction involving the complete or partial transfer of one or more electrons from one reactant to another

Question 2

Oxidation

Answer 2

The complete or partial loss of electrons from a substance involved in a redox reaction

Question 3

Reduction

Answer 3

The complete or partial addition of electrons to a substance involved in a redox reaction

Question 4

Oxidising Agent

Answer 4

The electron acceptor in a redox reaction

Question 5

Reducing Agent

Answer 5

The electron donor in a redox reaction

Question 6

Cellular respiration

Answer 6

The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP

Question 7

Aerobic Respiration

Answer 7

Are are catabolic pathway for organic molecules, using oxygen as the final electron acceptor in an electron transport chain and ultimately producing ATP. This is the most efficient catabolic pathway, and is carried out in most eukaryotic cells and many prokaryotic organisms.

Question 8

Anaerobic Respirstion

Answer 8

A catabolic pathway in which inorganic molecules other than oxygen accept electrons at the downhill end of electron transport chains

Question 9

Four sub-stages of cellular respiration

Answer 9

1. Glycolysis
2. Pyruvate Oxidation
3. Citric Acid Cycle
4. Oxidative Phosphorylation

Question 10

Glycolysis

Answer 10

Occurs in the cytosol of almost all living cells. It serves as the starting point for fermentation or cellular respiration. It begins the degradation process by breaking glucose into two molecules of pyruvate. There are two phase: energy investment (an input of energy is required) and energy payoff (energy is released).

Question 11

Pyruvate Oxidation

Answer 11

After glycolysis has split each glucose into 2 pyruvate, the pyruvate enter the mitochondrion and are oxidised to a compound called Acetyl CoA.

Question 12

Citric Acid Cycle (Krebs Cycle)

Answer 12

A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidising acetyl CoA (derived from pyruvate) to carbon dioxide; occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; together with pyruvate oxidation, the second major stage in cellular respiration.

Question 13

Oxidative Phosphorylation

Answer 13

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

Question 14

Which of the sub-stages of cellular respiration use oxygen?

Answer 14

Oxidative Phosphorylation

Question 15

Which of the sub-stages of cellular respiration do not use oxygen?

Answer 15

Glycolysis, Link, & Citric Acid Cycle

Question 16

What happens to the 6 Carbons of Glucose? When and where are they lost? What becomes of each carbon?

Answer 16

2 are lost during the link, when pyruvate (3 carbons) loses a carbon to CO2 in order to become an acetyl group (2 carbons). The other 4 are lost during the CAC—2 lost per time.

Question 17

Would it take greater or fewer numbers of enzymes if a cell could use both aerobic respiration AND fermentation?

Answer 17

GREATER! More processes, each chem. reaction needs enzymes, enzymes are specific

Question 18

Which classes of organic molecules yield the most the most ATP? (carbs, fats, proteins)

Answer 18

Fats!

Question 19

Which parts of these processes are anabolic? Catabolic?

Answer 19

It’s all catabolic!! Cellular respiration is the breakdown of glucose; catabolism breaks down molecules

Question 20

Anabolism

Answer 20

builds up molecules (synthesis)

Question 21

Catabolism

Answer 21

breaks down molecules (degradation)

Question 22

How is fermentation different for humans than yeast?

Answer 22

We use lactic acid fermentation while yeast uses alcohol fermentation. If humans were to use alcohol fermentation, every time we experienced a lack of oxygen (ex. shortness of breath when exercising), we would resort to fermentation as a means of producing ATP. The alcohol from the fermentation wold enter our bloodstreams, and essentially, exercise and general shortness of breath would result in drunkenness.

Question 23

How much ATP is typically produced from one glucose molecule? (How much is invested? How much is made? What is the total yield?)

Answer 23

Ideally, 38 ATPs are produced from cellular respiration, but in reality the number is closer to 29-30. In glycolysis, 2 ATPs are invested and it yields 4 ATPs, making for a net output of 2 ATPs. In the link, ?????. In the CAC, ?????. In OP/ETC, ?????.

Question 24

In which parts of the mitochondrion do the different stages of cellular respiration occur?

Answer 24

1. Glycolysis: cytoplasm
2. Link: moving acetyl from cytoplasm to matrix
3. Citric Acid Cycle: matrix
4. Oxidative Phosphorylation: cristae

Question 25

What are NAD+ and FAD? Why are they important? Which processes are they involved in? How are they used? Are they reusable?

Answer 25

• They’re coenzymes and oxidising agents (electron acceptors).
• They transport electrons and H+ to the electron transport chain.
• NAD+ is involved in all steps, FAD is involved only in the Krebs Cycle
• They are reusable (NAD+ —> NADH —> NAD+ …)

Question 26

Coenzyme

Answer 26

An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions.

Question 27

Substrate-Level Phosphorylation

Answer 27

The enzyme-catalysed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism. Occurs in glycolysis and the CAC.

Question 28

What is the difference between oxidative phosphorylation and substrate-level phosphorylation?

Answer 28

Amount of ATP produced; small amount in substrate-level phosphorylation, large amount in oxidative phosphorylation.

Question 29

In which stage(s) is oxidative phosphorylation used and when is substrate-level phosphorylation used? How are they different? The same?

Answer 29

Oxidative Phosphorylation: ETC
Substrate-Level Phosphorylation: Glycolysis & CAC
Both add a phosphate group to ADP but oxidative adds inorganic, while in substrate-level, enzyme adds phosphate from organic molecule to ADP.

Question 30

How is oxaloacetate important to the Krebs Cycle?

Answer 30

It’s the first reactant AND the final product. The cycle begins with acetyl (2C) + oxaloacetate (4c) —> citrate (6c)

Question 31

What happens when electrons are moved close to an electronegative atom? How is this useful in Cellular Respiration? Why is oxygen of particular interest in this process?

Answer 31

They are attracted to the electronegative atom. This is useful in cellular respiration, because oxygen, the final electron acceptor at the end of the ETC, must pick up low-energy electrons.

Question 32

Where does each stage exist and what is the overall purpose of each stage?

Answer 32

??

Question 33

What enters and leaves each sub-stage of cellular respiration?

Answer 33

Glycolysis: ?
Link: ?
Citric Acid Cycle: ?
Oxidative Phosphorylation: ?

Question 34

OIL RIG

Answer 34

Oxidation Is “Losing” & Reduction Is “Gaining”; in most cases it’y not a complete loss or gain of an electron, but rather within a bond, one atom hogs the electron.