Chapter 16. Glycolysis and Gluconeogenesis

Question 1

An ATP-generating process in which organic compounds act as both donors and acceptors of electrons; fermentations can take place in the absence of oxygen.

Answer 1

Fermentation

Question 2

the conversion of glucose into ethanol with a concomitant production of ATP.

Answer 2

Alcoholic fermentation

Question 3

the anaerobic metabolism of glucose to yield lactic acid with the concomitant production of ATP.

Answer 3

Lactic acid fermentation

Question 4

The first irreversible step in a metabolic pathway under physiologic conditions; this step is catalyzed by an allosteric enzyme and commits the product to a particular chemical fate.

Answer 4

Committed step

Question 5

the synthesis of glucose from noncarbohydrate precursors, including lactate, glycerol and amino acids.

Answer 5

Gluconeogenesis

Question 6

a hydrolytic enzyme that converts glucose 6-phosphate to free glucose for release into the blood; it is located in the liver and kidney.

Answer 6

Glucose 6-phosphatase

Question 7

a vitamin that plays a role in carboxylation and decarboxylation reactions.

Answer 7

Biotin

Question 8

an enzyme with two different, often opposing, catalytic activities on one polypeptide chain. For instance, phosphofructokinase 2 synthesizes fructose 2,6-bisphosphate and fructose 2,6-bisphosphatase hydrolyzes it, yet both active sites are on the same polypeptide chain.

Answer 8

Bifunctional enzyme

Question 9

activation of an allosteric enzyme in the latter section of a pathway by the product of a reaction that occurs earlier in the reaction pathway.

Answer 9

Feedforward stimulation

Question 10

An organism that metabolizes glucose aerobically when oxygen is present and performs fermentation when oxygen is absent.

Answer 10

facultative anaerobe

Question 11

A specialized isozyme of hexokinase which has a high KM for glucose and is not inhibited by glucose 6-phosphate.

Answer 11

glucokinase

Question 12

The use of lactic acid fermentation to generate ATP even the presence of enough oxygen to support cellular respiration.

Answer 12

Aerobic glycolysis

Question 13

a cyclic metabolic pathway in which lactate from active muscle is converted into glucose by the liver, which in turn supplies newly synthesized glucose to muscle and other tissues.

Answer 13

Cori cycle

Question 14

An allosteric enzyme that catalyzes the formation of fructose 6-phosphate and participates in the regulation of gluconeogenesis.

Answer 14

fructose 1, 6-bisphosphatase

Question 15

a kinase that phosphorylates fructose 6-phosphate to fructose 1,6-bisphosphate. Phosphofructokinase, an allosteric enzyme, is the major control point for flux through the glycolytic pathway.

Answer 15

phosphofructokinase (PFK)

Question 16

formation of ATP from ADP in which the phosphate donor is a substrate with high-phosphoryl transfer potential.

Answer 16

Substrate-level phosphorylation

Question 17

a sequence of reactions that convert glucose into pyruvate with a concomitant generation of energy.

Answer 17

Glycolysis

Question 18

an enzyme that catalyzes the attachment of a phosphoryl group to a substrate, using ATP as a phosphoryl donor.

Answer 18

Kinase

Question 19

a kinase that phosphorylates six carbon sugars, usually glucose, at the expense of ATP.

Answer 19

Hexokinase

Question 20

organisms that cannot survive in the presence of oxygen and thus are usually dependent on fermentation as an source of cellular energy.

Answer 20

Obligate anaerobe

Question 21

A key regulatory enzyme in glycolysis that catalyzes the formation of ATP and pyruvate from phosphoenolpyruvate and ADP.

Answer 21

Pyruvate kinase

Question 22

An ester in which the noncarbonyl oxygen atom is replaced by a sulfur atom; thioesters are energy-rich intermediates in a number of biochemical reactions.

Answer 22

Thioester intermediate

Question 23

A common nucleotide-binding domain in proteins that is made up of four α helices and a sheet of six parallel α strands.

Answer 23

Rossman fold

Question 24

A pair of thermodynamically irreversible biochemical reactions that simultaneously produce and consume a pair of metabolic intermediates; these paired pathways may amplify metabolic signals and in some cases can also generate heat for the maintenance of temperature in tissues. Also called futile cycle.

Answer 24

Substrate cycle

Question 25

Simultaneously decarboxylates and phosphorylates oxaloacetate to generate phosphoenolpyruvate.

Answer 25

phosphoenolypyruvate carboxykinase

Question 26

a biotin-dependent enzyme that catalyzes the formation of oxaloacetate from pyruvate and CO2 at the expense of ATP. Pyruvate carboxylase is important in gluconeogenesis as well as for replenishment of the citric acid cycle.

Answer 26

Pyruvate carboxylase