Flashcards in Lecture 8: Glucose Metabolism Deck (42):
What GLUT receptor is found in skeletal muscle, heart and adipose and is insulin dependent?
What GLUT receptor is the main ransporter in the liver and has low affinity with no regulation?
What GLUT transporter is the main transporter in the brain?
What GLUT transporter is high in RBCs and brain and has high affinity?
Where are glucokinase and hexokinase located?
Glucokinase is in the liver only, hexokinase is everywhere else
When is glucokinase inhibited?
When blood glucose is low -> it is no preferred to trap glucose in the liver so glucokinase will only be turned on in times of high glucose
When is DHAP made in glycolysis?
High energy state and excess glucose
- DHAP is converted to glycerol-3-phosphate then to fat
What is non-alcoholic fatty liver disease?
YOu have a buildup of energy and DHAP gets turned into fat
What stimulates pyruvate kinase?
Insulin and Fru-1,6-BP
What inhibits pyruvate kinase?
What inhibits hexokinase?
What stimulates glucokinase?
What inhibits glucokinase?
What stimulates PFK-1?
What inhibits PFK-1?
___________ is a disaccharide of glucose and fructose
_________ is a disaccharide of glucose and galactose
Where does galactose enter glycolysis?
- Then could go onto gycogenesis if no energy is needed
Where does fructose from adipose tissue enter glycolysis?
Where does fructose from the liver enter glycolysis?
DHAP or GAP
When is fructose quickly turned into fat?
In times of high energy
What does glucose-6-P feedback inhibit and when?
Hexokinase at times of rest
What is the role of glucose-6-phosphatase?
The convert GLucose-6-P to glucose in gluconeogenesis
Gluconeogenesis is the synthesis of glucose from noncarb precursors. What are the 3 major precursors?
Lactate, amino acids, glycerol
What is the rate limiting step of gluconeogenesis?
What are the 4 "bypass" enzymes in gluconeogenesis?
What 3 enzymes in glycolysis are involved in irreversible steps?
Where does gluconeogenesis occur and what is needed to get the starting materials?
Occurs in cytosol. Need to shuttle OAA out of mito by converting pyruvate -> OAA with pyruvate carboxylase then converting OAA -> Malate and malate leaves mito then is converted back to OAA in the cytosol
What stimulates Glucose-6-phosphatase?
What stimulates Fructose-1,6-bisphosphatase?
Citrate and cortisol
What inhibits fructose-1,6-bisphosphatase
AMP and fructose-2,6-BP
What stimulates PEPCK?
Cortisol, Glucagon, thyroxine
What stimulates pyruvate carboxylase?
Acetyl CoA and cortisol
What inhibits Pyruvate carboxylase?
What is Von Gierke disease?
A glycogen storage disease
- Glucose-6-phosphatase is defective so that the liver can release glucose into the blood stream resulting in fasting hypoglycemia, hyperlipidemia and damage to liver
In what 3 organs does gluconeogenesis occur?
How much ATP is used in one round of gluconeogenesis?
What is the rate limiting step of the pentose phosphate pathway?
Glucose-6-phosphate dehydrogenase (G6PD) (first step and the first time NADPH is made)
What inhibits G6PD in PPP?
What does a deficiency in G6PD of PPP cause?
Hemolytic anemia because of deficient levels of NADPH in RBCs. Altered G6PD produces low levels of NADPH, leading to low levels of reduced glutathione in RBCs, which is needed to maintain healthy RBCs
- This disorder is also called favism
What is the role of glutathione reductase?
Converts reversible reaction of oxidized glutathione -> reduced glutathione.
- The reduced glutathione cleans up ROS using its sulfhydril bond -> the oxidized form is formed after ROS has been picked up