Pentose Phosphate Pathway Flashcards Preview

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Flashcards in Pentose Phosphate Pathway Deck (9)
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1
Q

Pentose Phosphate Pathway

A
  • part of carbohydrate metabolism
  • occurs in cytoplasm of all cells
  • no ATP is consumed or produced
  • as glucose begins to go through glycolysis, some is shunted away and goes to this pathway
2
Q

What are the two functions of this pathway?

A
  • production of NADPH (functions in donating electrons which is important in anabolic reactions)
  • production of pentose sugar (ribose 5-phosphate) which is a substrate involved in nucleotide synthesis
3
Q

What are the two big phases of this pathway?

A
  1. oxidative phase

2. nonoxidative phase

4
Q

Oxidative Phase

A
  • begins with glucose 6-phosphate and ends with ribulose 5-phosphate
  • irreversible
  • major product is NADPH
  • rate-limiting enzyme: glucose 6-phosphate dehydrogenase
5
Q

Glucose 6-Phopshate Dehydrogenase

A
  • enzyme that converts glucose 6-phosphate to 6-phosphogluconate while reducing NADP+ to NADPH
  • activated by insulin and NADP+
  • inhibited by NADPH
6
Q

Non-Oxidative Phase

A
  • begins with ribulose 5-phosphate which can be broken down by an isomerase into ribose 5-phosphate
  • allows for interconversion of various sugars that can be used in biosynthesis
  • intermediates of this phase can feed into glycolysis (ex. fructose 6-phosphate, glyceraldehyde 3-phosphate)
  • reversible
7
Q

NAD+

A
  • much more of this form in the body compared to the reduced form (NADH)
  • high energy electron acceptor
  • potent oxidizing agent because it helps another molecule get oxidized while being reduced in the process
8
Q

NADPH

A
  • much more of this form in the body compared to the oxidized form (NADP+)
  • acts as an electron donor
  • potent reducing agent because it helps other molecules get reduced while being oxidized in the process
  • 3 primary functions: involvement in biosynthesis of lipids and cholesterol (precursor to steroid hormones), assist in cellular bleach production in white blood cells (contributes to bactericidal activity), maintains supply of reduced glutathione
9
Q

Glutathione

A
  • reducing agent
  • can help reverse free radical formation which prevents these free radicals from damaging DNA or lipids in the cell membrane