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Foundation Unit 2 > Glycolysis/Gluconeogenesis > Flashcards

Glycolysis/Gluconeogenesis Flashcards

1
Q

Oxidation

A

breaking down bonds and releasing energy

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2
Q

Biologically irreversible reaction

A

Delta G is so negative (-6kCal/mole or more) that the reverse reaction cannot occur bc the energetic roadblock is too high

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3
Q

Catabolic

A

break bonds and release energy (oxidative and degradative reactions)

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4
Q

Anabolic

A

making bonds

- requires energy (reductive and biosynthetic reactions)

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5
Q

Preparatory Phase

A
  • requires 2 ATP
  • two biologically irreversible steps
  • glucose to glyceraldehyde 3 phosphate
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6
Q

Energy producing phase

A
  • oxidation step
  • one biologically irreversible step
  • glyceraldehyde 3 phosphate to pyruvate
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7
Q

glucose phosphorylation

A

glucose to glucose 6-phosphate

  • enzyme = hexokinase
  • enzyme needs Mg+2 to neutralize neg charge density on ATP
  • bio irreversible
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8
Q

Glucokinase

A

works with organs that handle large quantities of available sugar

  • liver, kidney, intestine, and beta cells of pancreas
  • low affinity for glucose
  • matches blood glucose concentration after eating (50% active)
  • regulated by GKRP and F-6-P
    - excess F-6-P drives glucokinase back into inactive complex in nucleus
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9
Q

Hexokinase

A
  • predominant enzyme in most cells
  • has very high affinity for glucose
  • feedback inhibited by G-6-P
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10
Q

Glucokinase regulatory protein

A
  • activated by F-6-P

- excess F-6-P drives complex formation of glucokinase with GKRP back into inactive form in nucleus

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11
Q

Isomerization of Glucose 6 phosphate

A
  • moving electrons
  • enzyme = phosphohexose isomerase
  • product = fructose 6 phosphate
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12
Q

Phosphorylation of Fructose 6 phosphate

A
  • product = fructose- 1,6- bisphosphate
  • major site of metabolic regulation
  • 2nd biologically irreversible rxn
  • enzyme = phosphofructokinase 1 (PFK1)
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13
Q

cleavage of F-1,6-P2 into DHAP and glyceraldehyde 3 phosphate

A

-enzyme = aldolase

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14
Q

aldolase

A
  • enzyme that uses F-1,6-P2 or DHAP + glyceraldehyde-3-P as substrates
  • Aldolase A: muscle and red blood cells
  • Aldolase B: liver (will use F-1-P as substrate)
  • Aldolase C: brain
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15
Q

oxidation of glyceraldehyde-3-P

A
  • this step is activating inorganic phosphate in order to make ATP
  • NAD is reduced
  • energy released in oxidation is used to convert low energy phosphate to a high energy, unstable mixed anhydride
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16
Q

Nicotinamide Coenzymes

A
  • derived from Niacin
  • NAD(H) = catabolic pathways
  • or NADP(H) = anabolic pathways
  • niacin deficiency leads to pellagra
17
Q

2,3-bisphosphoglycerate

A
  • needed to keep phosphoglycerate mutase active
  • used in RBC to act as allosteric regulator of hemoglobin (binds to hemoglobin and lessen its affinity to oxygen so oxygen can be delivered to body)
18
Q

Regulation of Pyruvate Kinase

A
  • activated by fructose-1,6-bisphosphate
  • inhibited by ATP
  • in liver, covalent phosphorylation by PKA (cAMP) intensifies inhibition of ATP
19
Q

Brain glycolysis

A

aerobic glycolysis

- uses glucose

20
Q

Muscle glycolysis

A

either aerobic or anaerobic

- redder the muscle = more mitochondria it has and the more oxidative metabolism it can rely on

21
Q

red blood cell glycolysis

A

anaerobic glycolysis

  • no mitochondria (can’t do Krebs cycle and Ox. Phos.)
  • lactate is produced and dumped into the blood
22
Q

Liver glycolysis

A

glycolysis is an energy storing pathway in the liver as it releases glucose into the body when blood glucose levels are low

  • derives energy from oxidation of fatty acids
  • aerobic
23
Q

gluconeogenesis

A

largely takes place in the liver
re-synthesis of glucose
substrates: amino acid carbon skeletons, glycerol, and lactate

24
Q

Glucose-6-phosphatase

A
  • hydrolytic enzyme that takes phosphate off a molecule
  • occurs in the endoplasmic reticulum
  • a defect in any of the subunits will prevent glucose from leaving the liver and result in von Gierke’s disease (glycogen storage disease type I)
25
Q

Pyruvate carboxylase

A
  • enzyme to produce oxaloacetate from pyruvate
  • biotin is covalently attached to grab ahold of substrate
  • requires ATP
  • IN MITOCHONDRIA
  • avidin in egg whites prevents biotin absorption
  • maintains OAA levels to drive Kreb’s cycle

Foundation Unit 2 (3 decks)

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