Mitsoura - Glycolysis Flashcards Preview

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Flashcards in Mitsoura - Glycolysis Deck (31):
1

Describe the sources of GLUCOSE for glycolysis and how these sources are used as a function of metabolic state

Dietary intake (fed state), from glycogenolysis (fasting state), from gluconeogenesis (starving state - new glucose synthhesis)

2

Where is glucokinase found/located?

liver and pancreas only

3

Glucokinase has a high Km for glucose. What does this mean?

It has a low affinity for glucose and therefore it has a high Vmax

4

When does glucokinase work best?

Works best during the fed state to take in large amounts of blood glucose

5

What sugars does glucokinase have an affinity for?

only glucose!

6

Where is hexokinase found/located?

all tissues and organs outside liver and pancreas

7

When does hexokinase work best?

it works at all metabolic states

8

What effect does insulin have on glucokinase and hexokinase?

insulin has no effect on hexokinase, but glucokinase is inducible by it

9

What sugars does hexokinase have an affinity for?

Glucose, Galactose, and Fructose

10

What is the investment phase of glycolysis?

Step #1: Glucose → Glucose-6-Phosphate (enzyme: hexokinase/glucokinase)
Step #3: Fructose-6-Phosphate → Fructose-1,6-bisphosphate (enzyme: PFK-1)

11

What is the splitting phase?

Step #4: Fructose-1,6-bisphosphate → Glyceraldehyde-3-Phosphate (G3P) + Dihydroxyacetone Phosphate (DHAP)
(enzyme: Aldolase A)

12

How many energy generating steps are there?

there are 3 steps

13

List the first energy generating step

Step #: G3P ↔ 1,3-biphosphoglycerate
(enzyme: glyceraldehyde phosphate dehydrogenase)
generates 2 NADH

14

Where do the NADHs from the first energy generating step go?

to electron transport chain for ATP production

15

List the second energy generating step

1,3-biphosphoglycerate ↔ 3-Phosphoglycerate
(enzyme: phosphoglycerate kinase)
generates 2 ATP

16

List the third energy generating step

Phosphoenolpyruvate (PEP) → Pyruvate
(enzyme: pyruvate kinase)
generates 2 ATP
[this is a regulated step]

17

What is the net energy generated in glycolysis

2 ATP and 2 NADH

18

How much energy is produced anaerobically?

2 ATP, zero NADH

19

How does insulin stimulate glycolysis?

by activating PFK-2, catalyzing F-6-P → F-2,6-bisphosphate, which acts as an allosteric activator of PFK-1

20

How does glucagon inhibit glycolysis?

by activating F-2,6-bisphosphatase, catalyzing F-2,6-bisP → F-6-P, which then inhibits PFK-1

21

What stimulates and inhibits glucokinase?

stimulation: insulin and glucose
inhibition: glucagon and ATP

22

What inhibits hexokinase?

ATP and glucose-6-phosphate (G-6-P)

23

What stimulates and inhibits phosphofructokinase-1 (PFK-1)?

stimulation: AMP, Insulin, Fructose-2,6-bisphosphate
inhibition: Glucagon, ATP, Citrate (TCA cycle)

24

What stimulates and inhibits pyruvate kinase?

stimulation: Insulin, Fructose-1,6-bisphosphate
inhibition: ATP and Glucagon

25

When does lactic acidosis occur?

it occurs when there is a build up of lactate

26

What is the build up of lactate due to?

high concentrations of Pyruvate

27

What enzyme converts Pyruvate to Lactate?

Lactate Dehydrogenase

28

What diseases cause/result in lactic acidosis?

severe lung disease, Von Gierke's (GSD), Leukemia, Metastatic carcinoma

29

What two deficiencies cause/result in lactic acidosis?

Pyruvate dehydrogenase deficiency and α-ketoglutarate dehydrogenase deficiency

30

What 6 other conditions/factors result in lactic acidosis?

strenuous exercise, high altitude, drowning, carbon monoxide poisoning, cyanide poisoning, and alcohol intoxication

31

How does pyruvate kinase deficiency result in hemolytic anemia?

pyruvate kinase deficiency reduces amount of pyruvate produced, in turn reducing ATP produced via TCA cycle
structural integrity of RBCs decreases → forming acanthocytes → leading to cell lysis (aka: non-spherocytic hemolytic anemia)