Chapter 8 Glycolysis (slide notes)

Question 1

is glycolysis anabolic or catabolic process?

Answer 1

Trick question. it is both. ergo it is AMPHIBOLIC

Question 2

glycolysis converts one molecule of glucose to ___ molecules of pyruvate with the generation of ____ molecules of atp

Answer 2

2 molecules of pyruvate

2molecules of ATP

Question 3

break down the general two steps of glycolysis

Answer 3

stage 1. traps glucose in the cell and modifies it so that it can be cleaved into a pair of phosphorylated 3-carbon compount

2. oxidizes the 3 carbon compounds to pyruvate while generating 2 molecules of ATP

Question 4

what enzyme traps glucose in the cell and begins glycolysis

Answer 4

hexokinase

upon entering the cell through a specific transport protein, glucose is phosphorylated at the expense of ATP to form glucose-6-phosphate

hexokinase, which requires Mg+2 or Mn+2 as a cofactor, catalyzes the reaction

glucose 6 phosphate cannot pass through the membrane to the extracellular side

addition of phosphoryl group facilitates metabolism

Question 5

hexokinase, like most kinases, emplay substrate-binding ______ to minimize hydrolysis of ATP

Answer 5

substrate binding induced fit

Question 6

the conversion of glucose 6-phosphate to fructose 6-phosphate is catalyzed by __________ the reaction is readily _______-

Answer 6

phosphoglucose isomerase

the reaction is readily reversible

Question 7

frutose 1,6 bisphosphate is generated from glucose 6 phosphate. this reaction is catalyzed by the ______ enzyme ____________-

Answer 7

allosteric enzyme. phosphofructokinase (PFK)

Question 8

the six carbon sugar is cleaved into two three carbon fragments. where the delta G is

Answer 8

+23.8

Question 9

dihydroxyacetone phosphate to glyceraldehyde 3-phosphate uses what enzyme

Answer 9

triose phosphate isomerase

Question 10

Glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate uses what enzyme

Answer 10

glceraldehyde 3-phosphate dehydrogenase

Question 11

coupling through ______ intermediate can lower activation energy

Answer 11

thioester

Question 12

1,3-bisphosphoglycerate to 3 phosphoglycerate uses what enzyme?

Answer 12

phosphoglycerate kinase. (removes phosphate)

Question 13

why does PEP phosphenolpyruvate have such a high phosphoryl-transfer potential?

Answer 13

tautomerization. phosphoryl group traps pyruvate in an unstable enol form. when transfer of phosphoryl group is complete, enol converts to more stable ketone (pyruvate)

Question 14

`what are the 2 irreversible reactions of glycolysis?

Answer 14

hexokinase
phosphofructokinase-1 (PKF-1)
pyruvate kinase

Question 15

fermentations are ATP-generating pathways in which electrons are removed from one organic compound and passed to another organic compound. the formation of ethanol from pyruvate regenerates _______. pyruvate carboxylase requires the vitamam ________

Answer 15

regenerates NAD+

requires vitamen thiamine B1

Question 16

the conversion of glucose into two molecules of ethanol is called ___________

Answer 16

alcoholic fermentation

the NADH generated by glyceraldehyde 3-phosphate dehydrogenase is oxidized by alcohol dehydrogenase, generating NAD+

Question 17

the converstion of glucose into 2 molecules of lactate is called ____________-

Answer 17

lactic acid fermentation

Question 18

in the liver, fructose is metabolized by the ______ pathyway

Answer 18

fructose-1-phosphate

Question 19

in other tissues, such as adipose tissue, fructose is directly phosphorylated by _______

Answer 19

hexokinase

Question 20

galactose-glucose conversion pathway begins with the phosphorylation of galactose by __________-

Answer 20

galactokinase

Question 21

glucose 1-phosphate can be converted into glucose 6- phosphate by __________–

Answer 21

phosphoglucomuctase

Question 22

lactose intolerance or hypolactasia occurs because ___________

Answer 22

most adults lack the enzyme to degrade lactose

Question 23

enzymes catalyzing irreversible reaction in the metabolic pathway are potential CONTROL SITES

in glycolysis, these enzymes are ___,____,____

Answer 23

hexokinase, phosphofructokinase, and pyruvate kinase

Question 24

_________________ is the key regulator of glycolysis in mammals. the enzyme is allosterically ________ by ATP and allosterically ______ by AMP

(reverse process) when ATP needs are great, _______ generates ATP from 2 ADP. AMP then becomes the signal for low energy state

Answer 24

inhibited by ATP and allosterically stimulated by AMP

adenylated kinase

Question 25

_________, released by pancreatic alpha cells when blood sugar is low, actives the phosphatase fuction of PFK-2

Answer 25

glucagon…. this is hormonal regulation

also glucagon is then acting as a positive regulator for activation of PK2 therfore reducing the level of fructose 2,6, bisphospate

???? inconsistant

Question 26

______ released by pancreatic beta cells when blood glucose levels are high. the effects of this substance on glycolysis include activation of the kinase function PFK-2 which increases levels of fructose 2,6-bispohophate in the cell, in turn increasing glycolytic flux.

Answer 26

???? inconsistant

Question 27

hexokinase is allosterically _________

Answer 27

inhibited by glucose 6-phosphate

Question 28

pyruvate kinase is __________ and ________ stimulated by fructose 1-,6 bisphosphate the product of phosphofructokinase reaction

Answer 28

pyruvate kinase is inhibited by the allosteric signals ATP and alanine, and stimulated by fructose 1, 6- bisphosphate, the product of phosphofrcutokinase reaction

Question 29

in the muscle, _______ is regulated to meet the energy needs of contraction

Answer 29

glycolysis

Question 30

the key regulators of phosphofructokinase in liver are citrate which reports on the status of the citric acid cycle, and ___________

Answer 30

fructose 2,6- bisphosphate

citrate inhibits phosphofructokinase while fructose 2,6 bisphosphate is a powerful activator

Question 31

__________ is a form of the hexokinase found in hepatocytes. the high Km of glucokinase for glucose means that this enzyme is saturated only at very high concentrations of substrate.

Answer 31

glucokinase

glucokinase is active only after a meal, when blood glucose levels are high, this feature of hepatic glucokinase allows the liver to buffer blood glucose

Question 32

radpidly growing tumors obain ATP by metabolizing glucose to lactate even in presence of oxygen. a process termed aerobic glycolysis or the __________

Answer 32

Warburg effect

Question 33

the transcription factor hypoxia-inducible transcription factor 1 (HIF-1) faciliates aerobic glycolysis. exercise training also timulates HIF-1 which enhances the ability to generate ATP anaerobically and stimulate new blood vessel growth

Answer 33

general slide

Question 34

Insulin!

Answer 34

Insulin is secreted by β cells of the pancreas in response to high blood levels of glucose. This secretion is stimulated by the metabolism of glucose by the β cells.

Glucose enters β cells through GLUT2 and is metabolized to pyruvate, and the pyruvate is subsequently oxidized to CO2 and H2O.

The increase in ATP closes a K+ channel, which alters the charge across the cell membrane. This alteration in turn opens Ca2+ channels. The influx of Ca2+ ions stimulates the release of insulin.