Pentose Phosphate Pathway

Question 1

General Info

Answer 1

Also called Hexose Monophosphate Shunt
Occurs in the Cytosol
No ATP directly consumed or produced in this pathway
Produces: NADPH and Ribose-5-phosphate

Question 2

NADPH

Answer 2

NOT NADH OR NAD. It is a coenzyme. The difference is a phosphate group on one of the ribose.
Net: Glucose-6-phosphate, 2 NADP+, H20 –> Ribose-5-phosphate, 2 NADPH, 2H+, CO2
high energy molecule.
electrons are destined fro reductive biosynthesis

Question 3

NADPH uses

Answer 3

Adrenals –> Steroid Symthesis
Liver –> Fatty Acid & Cholesterol Synthesis
Testes —> Steroid Synthesis
Adipose Tissue –> Fatty Acid Synthesis
Ovary –> Steroid Synthesis
Mammary Glands –> Fatty Acid Synthesis
RBC –> Maintenance of reduced glutathoine

Question 4

Functions of NADPH

Answer 4

Reductive fatty acid biosynthesis
Reduction of hydrogen peroxide
Cytochrome P450 monooxygenase system
Phagocytosis by WBC
Cholesterol Biosynthesis 
Nucleotide biosynthesis

Question 5

NADP+ rises

Answer 5

This increases the rate of glucose-6-phosphate dehydrogenase which controlls the NADPH production. When NADPH is consumed NADP+ levels rise.

Question 6

Reduction of H2O2

Answer 6

Hydrogen peroxide is formed as by products of aerobic metabolism through Rxn with drugs, environmental toxins & diminished levels of antioxidants. All create oxidative stress (cell damage to dna, proteins, & unsaturated lipids) this can lead to cell death.

Question 7

Reduced Glutathione

Answer 7

can chemically detoxify hydrogen peroxide. The cell reduces glutathoine in a reaction catalyzed by glutathione reductase, using NADPH as a source of reducing electrons. Glutathione is the best free radical fighter, but it does not transport through the system very well. Glutathoine is formed from the AA’s Glycine, Cysteine, & Glutamate.

Question 8

Cytochrome P450

Answer 8

Mitochondrial System: function is to participate in the hydroxylation of steroids, a process that makes these hydrophobic compounds more water soluble.
Microsomal System: function is the detox of foregin compounds such as xenobiotics. Found associated with the membranes of the smooth ER particularly in the liver.

Question 9

Phagocytosis by WBC

Answer 9

Oxygen independent Mechanism: Includes the myeloperoxidase system and a system that generates oxygen derived free radicals
MPO system is most potent of the bactericidla mechanisms

Question 10

Syntehsis of Nitric Oxide

Answer 10

NO is a mediator in a broad array of biological systems. Relaxes vascular smooth muscle, acts as aneurotransmitter, preents platelet aggregation and plays an essential role in macrophage functions

Question 11

Glucose-6-phosphate Dehydrogenase Deficiency

Answer 11

Inherited disease characterized by hemolytic anemia caused by the inability to detoxify oxidizing agents. Found in the Middle East, Africa, and Asia. Leads to a shortened life span due to complications with chronic hemolysis. Found in 1 in 6 caucasians