Lecture 32 Flashcards
(9 cards)
G-6-P is shunted from glycolysis into the Pentose Phosphate Pathway (PPP), the three major products of which are ______-__-______ (used in DNA/RNA synth) and ______ (used in severeal anabolic rxns like fatty acid synth and used for maintaining evels of ROS), and ____-__-_____ (used in synth of aromatic AAs).
Ribose-5-phosphate
NADPH
Erythrose-4-phosphate
In the PPP, G-6-P is converted to ____-_-____ by the end the first phase known as the _______ phase which is ______(reversible or irreversible?). In the first step, the enzyme G-6-P ______ converts G-6-P to 6-phosphogluconolactone and produces ______ in the process (the last step in this phase, via the enzyme 6-phosphogluconate dehydrogenase, produces one as well). In the second phase, known as the ___-______ phase, which is _______ (reversible or irreversible?), ______-__-______ is converted to Ribose-5-phosphate via the enzyme _____-__-_____ _____. From there, the pathway uses tranketolase and transaldolase enzymes to produce different sized sugars based on the cell’s needs.
Ribulose-5-phosphate
Oxidative
Irreversible
G-6-P dehydrogenase
NADPH
Non-oxidative
Reversible
Ribulose-5-phosphate
Ribulose-5-phosphate isomerase
The _____ step of the PPP is the rate limiting step, which derives feedback from the amount or need for ______ in the cell (low levels stimulate; high levels inhibit).
First
NADPH
G-6-P dehydrogenase deficiency (G6PD) is __-_____ (inheritance) and is the most common disease producing enzyme abnormality in humans. Clinical manifestation includes ______ anemia, severe neonatal _______, and hyperbilirubinemia. Do these patients handle ROS well? Why?
X-linked
Hemolytic anemia
Neonatal jaundice
These patients do not handle ROS well, becuase their cells would produce less NADPH, an important reducing agent that activates glutathione, which reduces ROS - the first step of the PPP requires G-6-P dehydrogenase which produces NADPH when it converts G-6-P to 6-phosphogluconolactone.
Patients with G6PD have less activation of ______ via reduction by NADPH, which means they cannot handle ROS effectively. Remember that ROS can lead to the formation of _____ bonds between cysteine residues. When this occurs, the proteins denature and form insoluble masses called _____ bodies that attach to the RBC membrane, making them rigid. Removal of denatured Hb by macrophages in the _____ results in the formation of “____ cells.”
Glutathione
Disulfide
Heinz bodies
Spleen
Bite cells
“Ketchup is thicker than blood, but it’s tastier too, so the spleen can’t help but to take a BITE of you.”
Genetic deficiencies in NADPH oxidase cause chronic _____ disease, characterized by severe, persistent infections and formation of _____ that sequester bacteria that were not destroyed. If NADPH levels are low, it would have the same effect. Remember what it is necessary for in phagolysosomes. NADPH also has important roles in synthesis and actions of _____ _____ (most potent local vasodilator.)
Chronic Granulomatous Disease
Granulomas
Nitric Oxide
______-__-_____ _____ deficiency is a rare human disorder that leads to accumulation of polyols , like ribitol and arabitol, and is implicated in preipheral neuropathy and ________.
Ribulose-5-phosphate isomerase
Leukoencephalopathy
Fructosuria is caused by a deficiency in the enzyme ______. Hereditary _____ _____ is caused by a deficiency in Aldolase B, leading to severe disturbance of liver and kidney metabolism because of buildup of ____-__-_____, which leads to AMP degradation, hyperuricemia, severe ______glycemia, and _____ _____.
Fructokinase
Hereditary Fructose Intolerance
Fructose-1-Phosphate
Hypoglycemia
Lactic Acidosis
Sorbitol can be produced from glucose via ______ reductase. Accumulation of sorbitol in the cell leads to swelling bc sorbitol cannot exit the cell (increases the _____ pressure, so water flows in.) Think about the effects of swelling in a diabetic patient.
Aldose reductase
Osmotic pressure
