Week 10 - Unit 2 Flashcards
PPP stands for ?
Pentose MonoPhosphate Pathway- alternative oxidative pathway for glucose-6P
What are the two primary roles of PPP?
- Generation of 5-C sugars for nucleotide synthesis
- Generation of NADPH
(essential in red blood cell which does not have mitochondria to fully oxidize glucose)
The generation of ______ within the red blood cell is critical for the maintenance of glutathione in the reduced state.
NADPH
_______ is required to maintain hemoglobin in the reduced form to bind oxygen.
Glutathoine
Deficiencies in the ____ greatly impact red blood cell stability.
PPP
Fructose can come from what 3 sources?
- Dietary fructose (honey)
- Dietary Sucrose (Glucose + fructose)
- Converted from Glucose to Fructose in Polyol pathway
Fructose, like glucose, comes into the cell and is immediately phosphorylated by ?
Fructokinase
- Makes Fructose 1-P
Fructose ——-> Fructose -1P——–>(cleaved by what enzyme into two products?)
Aldolase B
Fructose—–>Fructose-1-P——>cleaved by Aldolase B ———–> (what are the two products?)
- Dihydroxyacetone - P
2. Glyceraldehyde
Aldolase B is active in what organ? how is it different from Aldolase A?
Aldolase B is in liver- used in both fructose and glucose pathway
Aldolase A- in muscle- only in glucose pathway
What does Aldolase B cleave in the Fructose pathway?
in the glucose pathway?
Fructose-1P
Fructose 1,6 Bisphosphate (glycolysis)
After Fructose 1-P is cleaved into Dihydroxyacetone-P and Glyceraldehyde, what must occur next for Glyceraldehyde before it can be used to make Pyruvate?
Glyceraldehyde is already 3-P version in glycolysis , but not in fructose pathway, so it must be phosphorylated by ATP into Glyceraldehyde 3-P
What is the enzyme that phosphorylates Glyceraldehyde in the fructose pathway to make its 3-P version?
Triose Kinase (takes P from ATP to make it ADP)
What is the rate limiting step for Fructose pathway ?
the Aldolase B enzyme (cleavage of Fructose 1-P)
Aldolase B has a much higher affinity for _______ in the Glycolysis pathway from glucose than _______ in fructose pathway.
Fructose 1,6 Bisphosphate
Fructose 1-P (will be much slower reaction)
After ingesting high amounts of fructose , normal individuals will accumulate ______ in the liver while is slowly cleaved by Aldolase B.
Fructose 1-P
Hereditary Fructose Intolerance is what type of genetic disorder?
Autosomal Recessive disorder
What are individuals missing in Hereditary Fructose Intolerance disorder?
Aldolase B
What happens to people with Hereditary Fructose Intolerance when they ingest fructose?
Accumulation of Fructose 1-P in liver (no aldolase B to cleave it)
- impacts ability to regulate blood glucose
- can lead to HYPOGLYCEMIA
- Can cause major clinical problems
What is Essential Fructosuria?
Individuals lack Fructokinase enzyme - can not convert fructose to fructose-1-P inside cells
-few clinical consequences
What happens when someone with Fructosuria ingests fructose?
It is not phosphorylated and metabolized but is rather just excreted in urine (sugar is not present in urine normally), few clinical problems
What enzyme will act on Galactose once it enters the cell?
Galactokinase (adds a Phosphate group to make Galactose 1-P)
Galactose 1-P interacts with UDP Glucose and is charged to UDP Galactose by what enzyme in a circular cycle?
Galactose 1-phosphate uridylyltransferase
What does Galactose 1-phosphate Uridylyltransferase do ?
It will charge Galactose 1-P to UDP Galactose while converting UDP glucose to Glucose 1-Phosphate for use in Glucose pathway and can be metabolized or maintain blood glucose levels