Chapter 7 - How Cells Harvest Energy

Question 1

The process utilized by cells to obtain energy from the oxidation of organic compounds accompanied by the consumption of oxygen (when available) and the release of carbon dioxide.

Answer 1

Respiration

Question 2

An organism capable of synthesizing its own food from inorganic substances using light or chemical energy. (eg:)

Answer 2

Autotroph

eg: green plants, algae, certain bacteria

Question 3

An organism that cannot manufacture its own food and instead obtains its food and energy by taking in organic substances, usually plant or animal matter.
(eg:)

Answer 3

Heterotroph

eg: animals, protozoans, fungi and most bacteria

Question 4

The process of oxidizing food molecules, like glucose, to carbon dioxide and water is called…

The energy released…

The process occurs in two phases:

Answer 4

cellular respiration

…is trapped in the form of ATP for use by all the energy-consuming activities of the cell.

1. glycolysis, the breakdown of glucose to pyruvic acid
2. the oxidation of pyruvic acid to carbon dioxide and water

Question 5

A chemical reaction that involves the removal of hydrogen from a molecule.

Answer 5

Dehydrogenation

Question 6

A chemical reaction that involves the addition of hydrogen to a molecule.

Answer 6

Hydrogenation

Question 7

Aerobic respiration

Answer 7

The process of producing cellular energy involving oxygen. Cells break down food in the mitochondria in a long, multistep process that produces roughly 36 ATP.

Question 8

Anaerobic respiration

Answer 8

A form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain. 2 ATP.

Question 9

Fermentation

Answer 9

An anaerobic process in which energy is released. Enzymes convert sugars (glucose, etc.) to ethyl alcohol. Frees NAD so it can participate in future reactions of glycolysis.

Question 10

Electron Transport Chain

Answer 10

A series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions, and transfers protons (H+ ions) across a membrane. Creates an electrochemical proton gradient that drives ATP synthesis.

Question 11

The final acceptor of electrons in the electron transport chain is…

Answer 11

Molecular oxygen

Question 12

Examples of Electron Transport Chain

Answer 12

Sunlight in photosynthesis and oxidation of sugars in cellular respiration.

Question 13

The addition of a phosphate (PO43−) group to a protein or other organic molecule. Turns many protein enzymes on and off, thereby altering their function and activity.

Answer 13

Phosphorylation

Question 14

The metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+.

Answer 14

Glycolysis

Question 15

An important enzyme that provides energy for the cell to use through the synthesis of ATP during chemiosmosis. It is formed from ADP and phosphate (Pi), and needs energy.

Answer 15

ATP synthase

Question 16

The molecule that is left over when a cell breaks down glucose during glycolysis.

Answer 16

Pyruvate

Question 17

Pyruvation then…

Answer 17

can either be further processed by entering the mitochondrion for aerobic respiration or changed into ethanol or lactic acid during fermentation.

Question 18

Acetyl-CoA’s main function…

Answer 18

Acetyl-CoA oxidizes fatty acids. Creates NADH & starts the Krebs cycle.

Question 19

An important molecule in metabolism, used in many biochemical reactions. Its main function is to convey the carbon atoms within the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production.

Answer 19

Acetyl-CoA

Question 20

A series of chemical reactions that generate energy through the oxidation of acetate derived from carbs, fats and proteins into CO2 and ATP.

Answer 20

Kreb’s Cycle

Question 21

The movement of ions across a selectively permeable membrane, down their electrochemical gradient. Relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis.

Answer 21

Chemiosmosis

Question 22

cytochrome C

Answer 22

Transfers electrons between Complexes III (Coenzyme Q - Cyt C reductase) and IV (Cyt C oxidase) in electron transport chain

Question 23

cytochrome oxidase complex

Answer 23

Complex IV. Catalyzes the final step in mitochondrial electron transfer chain, and is one of the major regulation sites for oxidative phosphorylation.

Question 24

ethenol fermentation

Answer 24

Elements such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products.

Question 25

lactic acid fermenation

Answer 25

Glucose and other six-carbon sugars (also, disaccharides of six-carbon sugars, e.g. sucrose or lactose) are converted into cellular energy and the metabolite lactate.

Question 26

bc1 complex

Answer 26

Links the electrons transfer from ubiquinol (or coenzyme Q) to cytochrome c and proton translocation across the inner mitochondrial membrane.

Question 27

NADH dehydrogenase

Answer 27

Enzyme located on the inner mitochondrial membrane that catalyzes the oxidation by NAD+ of pyruvate to acetyl-CoA. Links glycosis and Krebs Cycle.

Question 28

Steps of aerobic respiration

Answer 28

The first step in is glycolysis, the second is the citric acid cycle and the third is the electron transport system. The potential of NADH and FADH2 is converted to more ATP through an electron transport chain with oxygen as the “terminal electron acceptor”.

Question 29

Glycolysis produces:

Answer 29

2 ATP
2NADH
X 2Pyruvate

Question 30

Transition reaction produces:

Answer 30

2 NADH
X 2 CO2
X 2 Acetyl-CoA

Question 31

Kreb’s Cycle yields:

Answer 31

6 NADH
2FADH2
2 ATP

Question 32

Total ATP produced by electron transport & chemiosmosis

Answer 32

30-32 ATP

Question 33

Pyruvate yields:

Answer 33

Acetyl CoA & CO2. CO2 is released and Acetyl-CoA —> NADH & the Krebs cycle.

Question 34

Chemiosmosis

Answer 34

Hydrogen ions pass from the electron transport chain and diffuse from an area of high concentration to an area of lower proton concentration. The electrochemical concentration gradient of protons across the membrane can be harnessed to make ATP. Done by ATP synthase.

Question 35

ATP Synthase

Answer 35

Uses the kinetic energy to phosphorylate ADP, making ATP. Used in Chemiosmosis.

Question 36

Chemiosmosis yields:

Answer 36

NADH —–> 2 1/2 ATP

FADH2 —–> 1 1/2 ATP

Question 37

Complex I

Answer 37

NADH —–> NAD+

NADH —> 2e- & 2H+

Question 38

Complex II

Answer 38

FADH2 —–> FAD & 2H+

Question 39

cytochrome Q (ubiquinone)

Answer 39

e- from Complex I & II

Question 40

Complex III

Answer 40

e- from cytochrome Q

Question 41

cytochrome C

Answer 41

e- from complex III

Question 42

Complex IV

Answer 42

e- from cytochrome C

1/2O2 + 2H+ = H20