An Introduction to Metabolism/Cellular Respiration

Question 1

Metabolism

Answer 1

The sum of all chemical reactions in a cell or organism

Question 2

Activation Energy (Ea)

Answer 2

The minimum amount of energy that chemical reactants must absorb to start a reaction

Question 3

Exergonic reaction

Answer 3

A chemical reaction that releases free energy; the products have less free energy than the reactants
Ex. the burning of wood

Question 4

Endergonic reaction

Answer 4

A chemical reaction that absorbs free energy; the products have more free energy than the reactants
Ex. conversion of carbon dioxide and water into glucose and oxygen gas

Question 5

Catabolic pathway

Answer 5

A pathway in which energy is released and complex molecules are broken down into simple molecules
Ex. cellular respiration in which energy is extracted from the breakdown of food such as glucose

Question 6

Anabolic pathway

Answer 6

A pathway in which energy is supplied to build complex molecules from simple molecules
Ex. photosynthesis, the synthesis of macromolecules such as proteins or nucleic acids

Question 7

Phosphorylation

Answer 7

The transfer of a phosphate group, usually from ATP, to another molecule

Question 8

ATP cycle

Answer 8

The cyclic and ongoing breakdown and re-synthesis of ATP

Question 9

Dehydrogenase

Answer 9

An enzyme that oxidizes a substrate and transfers hydrogen ions to an acceptor

Question 10

NADH

Answer 10

The reduced form of the coenzyme nicotinamide adenine dinucleotide (NAD+)

Question 11

Aerobic cellular respiration

Answer 11

A process that uses oxygen to harvest energy from organic compounds

Question 12

Obligate aerobe

Answer 12

An organism that cannot live without oxygen

Ex. most eukaryotes, including all plants and animals

Question 13

Substrate-level phosphorylation

Answer 13

The formation of ATP by the direct transfer of a phosphate group from a substrate to ADP

Question 14

Oxidative phosphorylation

Answer 14

A process that forms ATP using energy transferred indirectly from a series of redox reaction

Question 15

Glycolysis

Answer 15

A series of reactions in which a glucose molecule is broken into two pyruvate molecules and energy is released

Question 16

Pyruvate oxidation

Answer 16

A reaction in which pyruvate is oxidized by NAD+, and carbon dioxide is removed, forming an acetyl group and releasing NADH

Question 17

Citric acid cycle

Answer 17

A cyclic series of reactions that transfers energy from organic molecules to ATP, NADH, and FADH2, and releases carbon atoms as carbon dioxide

Question 18

Anaerobic respiration

Answer 18

A process that uses a final inorganic oxidizing agent other than oxygen to produce energy

Question 19

Fermentation

Answer 19

A process that uses an organic compound as the final oxidizing agent to produce energy

Question 20

Obligate anaerobe

Answer 20

An organism that cannot survive in the presence of oxygen

Ex. protist Trichonympha or bacteria responsible for tetanus and botulism poisoning

Question 21

Facultative anaerobe

Answer 21

An organism that can live with or without oxygen

Ex. yeast

Question 22

Decarboxylation reaction

Answer 22

A chemical reaction that removes a carboxyl group to form carbon dioxide

Question 23

Dehydrogenation

Answer 23

The removal of a hydrogen atom from a molecule

Question 24

Proton gradient

Answer 24

A difference in proton (H+ ion) concentration across a membrane

Question 25

Proton-motive force

Answer 25

A force that moves protons because of a chemical gradient (often referred to as an electrochemical gradient) of protons across a membrane

Question 26

Chemiosmosis

Answer 26

A process in which ATP is synthesized using the energy of an electrochemical gradient and the ATP synthase enzyme

Question 27

Alcohol fermentation

Answer 27

A process in which pyruvate is decarboxylated, producing a molecule each of carbon dioxide and of ethanol, and an NAD+
Ex. wine and beer

Question 28

Lactate fermentation

Answer 28

A process in which pyruvate reacts with NADH and is converted directly into lactate and regenerates NAD+
Ex. making cheeses and flavour/preserve yogurt due to sour taste

Question 29

Energy coupling

Answer 29

The transfer of energy from one reaction to another in order to drive the second reaction