Unit 1 Ch 3 - Microbial Metabolism

Question 1

ABC (ATP-binding cassette) transport system

Answer 1

a membrane transport system consisting of three proteins, one of which hydrolyzes ATP; the system transports specific nutrients into the cell

Question 2

Activation energy

Answer 2

the energy required to bring the substrate of an enzyme to the reactive state

Question 3

Adenosine triphosphate (ATP)

Answer 3

a nucleotide that is the primary form in which chemical energy is conserved and utilized in cells

Question 4

Anabolic reactions (anabolism)

Answer 4

the sum total of all biosynthetic reactions in the cell

Question 5

Anaerobic respiration

Answer 5

a form of respiration in which oxygen is absent and alternative electron acceptors are reduced

Question 6

ATPase (ATP synthase)

Answer 6

a multiprotein enzyme complex embedded in the cytoplasmic membrane that catalyzes the synthesis of ATP coupled to dissipation of the proton motive force

Question 7

Autotroph

Answer 7

an organism capable of biosynthesizing all cell material from CO2 as the sole carbon source

Question 8

Calvin cycle

Answer 8

the series of biosynthetic reactions by which most phototrophs and many chemolithotrophs convert CO2 into organic compounds

Question 9

Catabolic reactions (catabolism)

Answer 9

biochemical reactions leading to energy conservation (usually ATP) by the cell

Question 10

Chemolithotroph

Answer 10

an organism that can grow with inorganic compounds as electron donors in energy metabolism

Question 11

Chemoorganotroph

Answer 11

an organism that obtains its energy from the oxidation of organic compounds

Question 12

Citric acid cycle

Answer 12

a cyclical series of reactions resulting in the conversion of acetate to two molecules of CO2

Question 13

Coenzyme

Answer 13

a small and loosely bound nonprotein molecule that participates in a reaction as part of an enzyme

Question 14

Electron acceptor

Answer 14

a substance that can accept electrons from an electron donor, becoming reduced in the process

Question 15

Electron donor

Answer 15

a substance that can donate electrons to an electron acceptor, becoming oxidized in the process

Question 16

Endergonic

Answer 16

a reaction that requires free energy

Question 17

Enzyme

Answer 17

a protein that can speed up (catalyze) a specific chemical reaction (a few RNAs are also enzymes)

Question 18

Exergonic

Answer 18

a reaction that releases free energy

Question 19

Fermentation

Answer 19

anaerobic catabolism in which an organic compound is both and electron donor and an electron acceptor and ATP is produced by substrate-level phosphorylation

Question 20

Free energy (G)

Answer 20

energy available to do work; G0 is free energy under standard conditions

Question 21

Glycolysis

Answer 21

a biochemical pathway in which glucose is oxidized to pyruvate, which is either used in respiration or fermented; yields ATP and, in fermentation, various fermentation products (aka Embden-Meyerhof-Parnas pathway)

Question 22

Glyoxylate cycle

Answer 22

a modification of the citric acid cycle in which isocitrate is cleaved to form succinate and glyoxylate during growth on two-carbon electron donors as acetate

Question 23

Group translocation

Answer 23

an energy-dependent transport system in which the substance transported is chemically modified during the process of being transported by a series of proteins

Question 24

Heterotroph

Answer 24

an organism that uses organic compounds as a carbon source

Question 25

Oxidative phosphorylation

Answer 25

the production of ATP from a proton motive force formed by electron transport of electrons from organic and inorganic electron donors

Question 26

Pentose phosphate pathway

Answer 26

a series of reactions in which pentoses are catabolized to generate precursors for nucleotide biosynthesis or to synthesize glucose

Question 27

Photophosphorylation

Answer 27

the production of ATP from a proton motive force formed from light-driven electron transport

Question 28

Phototrophs

Answer 28

organisms that use light as their source of energy

Question 29

Proton motive force (pmf)

Answer 29

a source of energy resulting from the separation of protons from hydroxyl ions across the cytoplasmic membrane, generating a membrane electrochemical potential

Question 30

Reduction potential (E0’)

Answer 30

the inherent tendency, measured in volts under standard conditions, of a compound to donate or to accept electrons

Question 31

Respiration

Answer 31

the process in which a compound is oxidized with O2 (or an O2 substitute) as the terminal electron acceptor, usually accompanied by ATP production by oxidative phosphorylation

Question 32

Simple transport system

Answer 32

a transporter that consists of only a membrane-spanning protein and is typically driven by energy from the proton motive force

Question 33

Substrate-level phosphorylation

Answer 33

the production of ATP by the direct transfer of an energy-rich phosphate molecule from a phosphorylated organic compound to ADP