Carb Metabolism 4 Flashcards
Where does glycogen synthesis occur?
liver and muscle
Glucose 6 P —> ? –> gluc 1 p?
phosphoglucomutase
glu 1 P –> ? –> UDP glucose?
UDP-glucose pyrophosphorylase
Glycogen is synthesized in the cytosol on a primer protein called?
glycogenin
What enzymes transfers glucose residues from UDP-glucose to the nonreducing ends of glycogen chains?
glycogen synthase
Branching is introduced on glycogen by what enzyme?
branching enzyme
When does glycogen degradation occur?
when blood glucose levels are low
What enzyme is the first step in glycogen degradation?
glycogen phosphorylase
What process involves glycogen phosphorylase, phosphoglucomutase, glucose 6 phosphatase and debranchnig enzymes?
glycogen degradation
What process involves hexokinase, phosphoglucomutase , UDP-glucose pyrophosphorylase, glycogen synthase, and branchign enzymes?
glycogen synthesis
During glycogen degradation, what is released from debranched chains of a 1,4 linked glucoses?
glucose phosphates
Glucokinase is NOT inhibited by what product?
gluc 6 phosphate
Glycogen synthase is stimulated by what? Inhibited by what?
+ insulin
- glucagon, epinephrine
Insulin ____ blood sugar concentration.
Glucagon _____ blood sugar concentration.
Epinephrine ____ ATP production from glycogen and glucose.
lowers
raises
stimulates
Can muscles respond to glucagon? Why or why not?
NO!!!! they cannot release glucose as they are lacking glucose 6 phosphatases
In response to epinephrine, what happens in the liver and muscle?
stimulates breakdown of glycogen in the liver
activate glycolysis in the muscle to make ATP
Phosphorylation favors glycogen ______?
degradation
In their phosphorylated states, glycogen phosphorylase is what and glycogen synthase is what?
glycogen phosphorylase –> active
glycogen synthase –> inactive
Steps of glucagon binding in the liver in response to low levels of glucose.
- glucagon and epinephrine bind to cell surface receptors.
- adenylate cyclase activated
- increased cAMP –> activates PKA
- PKA activates phosphorylase kinase by phosphorylation
- phophorylase kinase phosphorylates glycogen phosphorylase
In response to insulin, insulin binds to what type of receptor on the cell to initiate it’s response?
protein phosphatase 1 (PP1)
What does PP1 do?
activates glycogen synthase and inactives glycogen phosphorylase
Insulin causes what 4 effects in the liver?
activates glycogen synthase
inactiviates glycogen phosphorylase
stimulates glycolysis and ATP generation
no effect on glucose update
Glucagon causes what 4 things in the liver?
activates, glycogen phosphorylase, glucose 6 phosphatase, and glycogeneogenesis
inhibits glycogen synthase
Epinephrine causes what 4 things in the liver?
activates glycogen phosphorylase and glucose 6 phosphate
inactivates glycaon synthase
does NOT STIMULATE GLYCOLYSIS
Insulin effects in the muscle? 3 thigns
stimulates glucose uptake, stimulates glycolysis and ATP, increase muscle glycogen and creatine phosphate levels
Effects of glucagon on muscle?
NONE
Effects of Epinephrine on the muscle?
activates glycogen phosphorylase and inactivates glycogen synthase
stimulates glycolysis
Before breakfast, what is the main source of blood glucose?
gluconeogensis
Wha is van Gierke disease?
defect in gluocse 6 phosphatase; liver and kidney cannot export glucose and leads to hypoglycemia and increased liver glycogen stores
Type 1 glycogen storage disease name?
van Gierke
Van Gierke is what # glycogen storage disease? WHy?
Type 1; defect in glucose 6 phosphatase
What is Pompe Disease?
deficiency in acid maltase (or a-glucosidease); accumulation of glycogen in the lysosomes over time
What is Type II glycogen storage disease?
Pompe
What is Cori Disease?
Type III, disease in glycogen debranching enzyme
What is Type 5 glycogen disorder disease?
McArdle; defect in muscle glycogen phosphorylase; unable to break down glycogen; muscle cramps during exercise
What disease presents with muscle cramps during periods of high glucose demands?
McArdle’s; Type 5
What are the 2 mechanisms in which alcohol metabolism occurs?
- Alcohol dehydrogenase and Aldehydge Dehydrogenase
2. p450 system (MEOS)
What is one bad thing about the MEOS system?
oxidize NADPH; do you wont have as much
Ethanol metabolism reduces the amount of what and increases the amount of what in the cytoplasm?
decrease NAD and increases NADH
What 2 mechanisms are affected when NADH is high?
pyruvate and OAA will get converted quickly by Lactate DH and malate DH –> lactate and malate
Ethanol metabolism in the liver generates NADH, which reduces the capacity for what and blocks what?
reduces the capacity for gluconeogeneis
and blocks CAC
