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Bichem > Glycolysis > Flashcards

Glycolysis Flashcards

1
Q

Glycolysis

A
  • break down glucose and provide energy by ATP
  • ANAEROBIC PATHWAY
  • end product is pyruvate
  • happens in the cytosol
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2
Q

The fate of pyruvavte in humans depends on

A
  • whether or not an adequate supply of oxygen is available

- whether mitochondria are present

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3
Q

Aerobic glycolysis

A
  • in cells with oxygen and mitochondria
  • pyruvate is final end product
  • NADH from glycolysis is oxidized to NAD+ and oxygen is the final electron acceptor
  • NAD+ IS REQUIRED FOR GLYCOLYSIS TO PROCEED
  • pyruvate will continue to TCA cycle
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4
Q

Anaerobic glycolysis

A
  • lack mitochondria or oxygen
  • pyruvate is the final electron acceptor
  • pyruvate is converted lactate
  • allows for the regeneration of NAD+
  • no TCA cycle
  • pyruvate to lactic acid is the final step
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5
Q

Transport of glucose into cell

A

-glucose cant diffuse into the cell because it is hydrophyllic and cant get through the lipid bi layer of the membrane

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6
Q

Glucose transporter (GLUT)

A
  • GLUT proteins span the membrane
  • ATP independent (passive transport)
  • glucose binds and changes shape so it can pass through the membrane
  • moves from more concentrated to less concentrated
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7
Q

GLUT 1

A

in most tissues, abundant in brain and RBC

-basal uptake of glucose

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8
Q

GLUT 2

A

liver, pancreatic beta cells

-glucose uptake and release by the liver

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9
Q

GLUT 3

A

in most tissues, abundant in brain and RBC

-basal uptake of glucose

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10
Q

GLUT 4

A

Skeletal muscle and adipose tissue

  • insulin stimulated glucose uptake stimulated by exercise
  • ON THE PLASMA MEMBRANE ALL THE TIME
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11
Q

GLUT 5

A
  • tissue specific
  • specific regulation
  • specificity for substrate
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12
Q

SGLT system

A
  • transport glucose against its concentration gradient by co-transporting Na+ down its gradient.
  • active transport
  • epithelial cells of intestines, renal tubes,choroid plexus
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13
Q

What are the two stages of glycolysis

A
  • energy investment phase(1)

- energy generation phase (2)

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14
Q

Name the two coupled reactions with the hydrolysis of ATP

A

Step 1- phosphorylation of glucose to glucose 6-phosphate

Step 3- phosphorylation of fructose 6-phosphate

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15
Q

Name the two coupled reactions by substrate level phosphorylation

A

Step 7- Synthesis of 3-phosphoglycerate producing ATP

Step 10- Formation of pyruvate and production of ATP

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16
Q

What are the three irreversible reactions

A
  1. Step 3-phosphorylation of fructose 6-phosphate (inhibited by citrate and ATP)(activated by high AMP levels)
  2. Step 1- phosphorylation of glucose to glucose 6-phosphate (Hexokinase regulated by negative feedback of glucose 6-phosphate)
  3. Step 10-formation of pyruvate and production of ATP(regulated by glucagon-inactivates kinase and insulin-activates kinase)
17
Q

What is the rate limiting step?

A

Step 3: Phosphorylation of fructose 6-phosphate

  • PFK-1 regulation
  • too high ATP and citrate inhibit reaction
  • low AMP activate reaction
  • positive regulation from PFK-2
18
Q

SGLT System

A
  • Active transport of glucose against it’s gradient
  • requires energy supplied by Na or K ATPase that pumps Na outside the cell to create the gradient
  • in intestines, renal tubules, choroid plexus
19
Q

NET OUTCOME OF GLYCOLYSIS

A

Glucose—->2 pyruvate
2ADP———>2 ATP
2 NAD+———->2 NADH

anaerobic- NADH cannot be converted to ATP
Aerobic-NADH CAN be converted to ATP(net yield 8 ATP)

20
Q

What are the two steps for NADH stuff

A

Step 6: oxidation of glyceraldehyde 3-phosphate
NAD+—–>NADH
Step 10b- Pyruvate to lactate (only for anaerobic)
NADH——>NAD+

21
Q

After step 10

A

aerobic-ETC, pyruvate converted to acetyl coA and create even more energy
Anaerobic- reduce to lactate(reversible) to generate NAD+

22
Q

RBC

A
  • need glycolysis because they have no mitochondria and rely on it for energy (ATP)
  • without it, hemolytic anemia and cell death
23
Q

Consequences of lactate build up

A
  • normal in exercising muscle and RBC
  • too much lowers pH and causes cramping
  • can lower intracellular pH to denature enzymes and cause cell death (MI, pulmonary embolism, hemorrhage)
  • lactic acidosis(lower pH of blood)
24
Q

Alternative fates of pyruvate

A
  1. pyruvate—->acetyl coA: TCA cycle, irreversible, important for cardiac muscle
  2. pyruvate—>oxaloacetate: can replinish TCA cycle intermediates, can be used for gluconeogenesis
  3. pyruvate—->ethanol: not in humans
  4. Pyruvate—-> lactate

Bichem (9 decks)

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