Unit Two B And C Flashcards
How can glucokinase function at higher glucose levels
Not inhibited by glucose 6 phosphate
Phosphorylation of glycogen phosphorylase (increases or decreases) glycogen degradation
Increases
What inhibits pyruvate dehydrogenase complex
Acetyl CoA
Pyruvate kinase activated by what allosterically
Fructose 1,5-bisphosphate
What enzyme turns pyruvate to oxaloacetate
Pyruvate carboxylase
If AMP is high and ATP is low what occurs
Glycolysis
HK 1 is expressed where
All tissues to different levels
glucokinase is expressed where
Liver and pancreatic B cells
Why does pyruvate kinase becomes inactivated
Glucose depletion in liver only
Characteristics of hexokinase
Present in all tissues, high affinity for glucose, low Km, low Vmax, inhibited by glucose 6 phosphate, constitutive
What are the branches of glycogen
Alpha 1-4 and alpha 1-6
What inhibits FBPase-2
Phosphoprotein phosphatase
Fructose 2,6-bisphosphate is produced from
Fructose 6-phosphate
Synthesis of glycogen starts as
Glucose 6 phosphate to glucose 1 phosphate
Deficiency in cori disease
4:4 transferase, or 1:6 glucosidase
Function of Glut 2
In pancreas, regulation of insulin. In liver, removes excess glucose from blood
What levels of ATP stimulate glycogen phosphorylase activity
Low ATP levels
Glycogen is a polymer of
Glucose
In pompe disease, what deficiency leads to accumulation of glycogen in lysosomes
Lysosomal alpha 1-4 glucosidase
What inactivated PFK2
CAMP dependent protein kinase
What enzyme is used in glycogenolysis
Glycogen phosphorylase
What is the deficiency in von gierke disease
Glucose 6 phosphatase
How do the glycosidic bonds in glycogen cleave during glycogenolysis
Cleavage of alpha 1-4 glycosidic bonds from non reducing end until 4 residues from branch point
What turns glucose one phosphate into UDP glucose
UDP pyrophosphorylase
Glucokinase kM
Higher so responsive to higher concentrations of glucose
Comment of Glut 4
Amount in muscle plasma membrane increases with endurance training
ATP regulates what enzyme
Phosphofructokinase-1
Function of glucokinase
Clear blood glucose at higher concentrations of glucose for storage as glycogen
What activates FBPase2
CAMP-dependent protein kinase
What enzyme needed to make F2,6 bisphosphate
PFK-2
What acts as an allosteric activator in glycogen synthase in the liver and muscle
Glucose 6 phosphate
What protein serves as a nidus for glucose to attach and acts as an enzyme (glycogen synthase activity) to form a linear poly glucose chain containing at least 8 glucose units to serve as a primer for glycogen synthas
Glycogenin
Cofactor for glycogenolysis
Pyridoxal phosphate
What activates cAMP dependent protein kinase
Glucagon
What enzyme turns pyruvate into acetyl CoA
Pyruvate dehydrogenase complex
What are isozymes
Different enzymes that catalyze the same reaction
If AMP is low and ATP high what occurs
Gluconeogenesis
What is ATP in the commitment step in glycolysis
Substrate and negative effector
Glycogen synthase requires
Glycogenin
Glucose one phosphate becomes what in glycogenesis
UDP glucose
Function of Glut 5
Fructose transporter
What are the two alternative fates of pyruvate
New glucose or acetyl CoA
Isozymes share similar
Sequences
What activates phosphoprotein phosphatase
Insulin
What are the linear form of glycogen
Alpha 1-4
Size of glycogen
10^8 daltons
Why do we not spend glucose in glycolysis
If there is plenty of ATP
Tissue location of Glut 5
Small intestine
Function of glycogen synthase
Elongation of glycogen fragment
Deficiency in McArdle syndrome
Myophosphorylase
Characteristics of glucokinase
Present in liver and pancreatic B cells, high Km, high Vmax, responds to changes in glucose concentrations, induced by insulin
What is the allosteric inhibitor of glycogen phosphorylase in the liver and muscle
Glucose 6 phosphate and ATP
What is the branching enzyme for glycogenesis
4:6 transglucosidase activity
Function of fructose 2,6-bisphosphate
Regulate glycolysis and gluconeogenesis
Function of glycogenin
Synthesis of primer
What are the three targets of insulin in myocte
Glut 4, hexokinase and glycogen synthase
Fructose 2,6-bisphosphate inhibits
1,6-bisphosphatase (gluconeogenesis)
Liver glycogen is used for
Blood glucose homeostasis
Tissue location of Glut 2
Liver and pancreatic B cells
What is the coenzyme for pyruvate carboxylase
Biotin
What activates pyruvate carboxylase
Acetyl CoA
If pyruvate becomes acetyl CoA it can
Store energy as body fat, make ATP via citric acid cycle
How to make fructose 6-phosphate from F2,6BP
FBPase-2
Pryuvate kinase allosterically inhibited by
ATP, acetyl CoA, long chain fatty acids and alanine
Fructose 2,6-bisphosphate is not
A glycolytic intermediate but a regulator
If pyruvate becomes glucose it can
Store energy as glycogen, generate NADPH vie pentose phosphate pathway
Product of glycogenolysis
Glucose one phosphate and shortened glycogen fragment (limit dextrin)
Acetyl CoA stimulates what
Glucose synthesis by activating pyruvate carboxylase
What activates PFK2
Phosphoprotein phosphatase
Muscle glycogen is used for
Fuel reserve for ATP synthesis
Tissue location of Glut 4
Muscle and fat cells
What is the commitment step in glycolysis
Fructose 6 phosphate to fructose 1,6-bisphosphate
Fructose 2,6-bisphosphate activates
Phosphofructokinase (glycolysis)
