Pentose Phosphate Pathway Flashcards
(47 cards)
The pentose phosphate pathway provides a major source of what compound?
NADPH
This pathway will also provide what sugar for the synthesis of ribonucleotides?
Ribose-5-phosphate
The oxidative portions of the pentose pathway have how many reactions that lead to the formation of ribulose-5-phosphate?
Three
The oxidative portion of the pentose pathway will produce what products (3) for each molecule of glucose-6-phosphate oxidized?
Ribulose-5-phosphate
CO2
two molecules of NADPH
This pathway is important for what 3 processes in the body?
- NADPH - dependent synthesis of fatty acids
- NADPH - dependent synthesis of steroid hormones
- Erythrocytes which require NADPH to keep glutathione reduced.
NADPH-dependent synthesis of fatty acids is important in what parts of the body?
Liver, mammary glands, and adipose
Synthesis of steroid hormones is important for what structures in the body?
Testes, ovaries, adrenal cortex, and placenta.
Where does the oxidative stage of the pentose pathway occur in the cell?
Cytosol
Glucose 6 phosphate dehydrogenase will catalyze an irreversible oxidation of glucose 6 phosphate into ______.
6-phosphogluconolacetone
The dehydrogenation of glucose 6-phosphate needs a specific coenzyme what is it?
NADP+
What will inhibit the dehydrogenation of glucose 6-phosphate?
NADPH
What hormone up regulates the dehydrogenation of glucose-6 phosphate to 6-phosphogluconolacetone? Is this step rate limiting?
Insulin - yes it is rate limiting
What does 6-phosphogluconaolacetone hydrolyze to?
6 phosphogluconate
6 phosphogluconate is than converted to what sugar? What other compounds are released during this run?
ribulose 5-phosphate, CO2 and NADPH
In what cell types does the non-oxidative reactions of the pentose pathways take place?
ALL cell types synthesizing nucleotides and nucleic acids.
The reversible reactions permit ribulose-5-phosphate to be converted to what 3 compounds?
- Ribose 5-phosphate
- fructose 6-phosphate
- glyceraldehyde 3-phosphate
How does NADP+ differ from NAD+?
The presence of a phosphate group on one of the ribose subunits.
The high energy electrons of NADPH will be used for what function in the cell?
Reducing equivalence
What reactive oxygen species (ROS) is formed from the partial reduction of molecular oxygen?
Hydrogen peroxide
The highly reactive species of free radicals can cause what type of damage to the body?
Damage to DNA, proteins, lipids leading to cellular damage and death.
What is present in most cells that can chemically detoxify hydrogen peroxide?
Reduced Glutathione, a tripeptide-thiol
What is Glutathione composed of?
Glutamate, cysteine and glycine
Once Glutathione is oxidized to detoxify hydrogen peroxide how is it rejuvenated?
NADPH with the enzyme glutathione reductase.
What does the breakdown of hydrogen peroxide by glutathione produce as end products?
2 water molecules and a dimerized glutathione