Uworld glycogen

Question 1

In McArdle deficient enzyme is …….

Answer 1

Skeletal muscle glycogen phosphorylase [MYOPHOSPHORYLASE]

Question 2

What is the location of the damage in McArdle?

Answer 2

Skeletal muscle

Question 3

Management of McArdle?

Answer 3

Consume simple sugars before exercise

Question 4

Hallmark of McArdle?

Answer 4

Flat venous lactate curve with normal rise in ammonia levels during exercise

Question 5

Function of myophosphorylase?

Answer 5

Cleaves 1,4 bonds from glycogen until there is left 4 1,4 alpha glycosidic bond to 1,6 bond. As a result we have limit dextrin

Question 6

Glucosyltransferase function?

Answer 6

cleaves 3 outer glucosed residues of the 1,6 branch and transfer them to linear glycogen branch

Question 7

alpha1,6-glucosidase function?

Answer 7

debranch the last molecule 1,6 from the branch and release it as a free glucose.

Question 8

What 2 processes regulate glycogen phosphorylase?

Answer 8

phosphorylation (active); dephosphorylation (inactive)

Question 9

What is responsible for the phosphorylation of glycogen phosphorylase?

Answer 9

phosphorylase kinase

Question 10

What is responsible for the dephosphorylation of glycogen phosphorylase?

Answer 10

phosphoprotein phosphatase

Question 11

For what purposes is used glycogen in liver and muscle?

Answer 11

Liver –> maintain glucose during the fasting state

Muscle –> provide energy for muscle contraction

Question 12

What activates protein kinase in liver?

Answer 12

Glycogen and epinephrine

Question 13

Activation of ……………… receptors in liver increases cAMP?

Answer 13

Gs protein coupled

Question 14

What receptors lack muscle?

Answer 14

Glucagon

Question 15

Whan induces activation on PK in muscle if there is lack of glucagon receptors?

Answer 15

Epinephrine

Question 16

What is more powerful activator of muscle PK than epinephrine?

Answer 16

Calcium

Question 17

What inhibit active form of phosphorylated glycogen phosphorylase?

Answer 17

ATP and glucose-6-phosphate

Question 18

What helps to distinguish Cori disease from other glycogen storage diseases with hepatic involvement?

Answer 18

Muscle weakness and hypotonia

Question 19

What is key distinguishing feature of Cori diseases (histology)

Answer 19

cytosolic accumulation of glycogen with abnormally short outter chains (limit dextrins)

Question 20

What hepatic changes are seen in Cori?

Answer 20

hepatic fibrosis; fatty infiltration is not seen

Question 21

What are two debranching enzymes in glycolysis synthesis?

Answer 21

Glucosyltransferase; alpha-1,6- glucosidase

Question 22

Pompe disease is caused by deficiency of …………….

Answer 22

alpha-1,4-glucosidase/acid maltase

Question 23

What environment is needed for alpha-1,4-glucosidase?

Answer 23

acidic environment of lysosome

Question 24

Where is degraded majority of glycogen in a cell?

Answer 24

cytoplasm

Question 25

Deficiency of acid maltase results in pathologic accumulation of glycogen within ………………………………………

Answer 25

liver and muscle lysosomes

Question 26

Why there is affected cardiac and skeletal muscles in pompe disease?

Answer 26

Cardiac and skeletal muscle are particularly susceptible because the ballooning lysosomes interfere with contractile function.

Question 27

Biopsy of Pompe?

Answer 27

glycogen in lysosomes.