Glycogen

Question 0

Glycogen-glucagon

Tissue?

Answer 0

Liver

Question 1

Glycogen-epinephrine

Tissue

Answer 1

Liver and muscle

Question 2

Glucogen-insulin

Tissue?

Answer 2

Liver and muscle

Question 3

Protein responsible for glycogen synthesis

Answer 3

Glycogen synthase

Question 4

Protein responsible for glycogen hydrolysis

Answer 4

Glycogen phosphorylase

Question 6

Glucagon-glycogen pathway

Answer 6

Glucagon receptor (LIVER) --> adenylate cyclase --> increased cAMP --> PROTEIN KINASE A --> glycogen phosphorylase kinase --> glycogen phosphorylase --> glycogen to glucose 
(Protein kinase A is a glycogen synthase inhibitor)

Question 7

Epinephrin - glycogen pathway

Answer 7

1. Epinephrin β receptor (liver or muscle) –> adenylate cyclase –> increased cAMP –> PROTEIN KINASE A –> glycogen phosphorylase kinase –> glycogen phosphorylase –> glycogen to glucose (Protein kinase A is a glycogen synthase inhibitor)
2. Epinephrin α receptor (LIVER) –> increased calcium from endoplasmic reticulum. Calcium can activate glycogen phosphorylase kinase :
3. Directly
4. Via calcium-calmodulin in muscle during contraction

Question 8

Alternative epinephrin glycogen pathway

Answer 8

Epinephrin α receptor (LIVER) –> increased calcium from endoplasmic reticulum. Calcium can activate glycogen phosphorylase kinase :

1. Directly
2. Via calcium-calmodulin in muscle vis contraction

Question 9

Insulin action on glycogen synthesis

Answer 9

Tyrosine kinase dimer receptor (liver + muscle)

• inhibits glycogen phosphorylase via protein phosphatase
• induce glycogen synthase (directly or via protein phosphatase)

Question 9

Insulin action on glycogen synthesis inhibits glycogen phosphorylase via

Answer 9

Tyrosine kinase dimer receptor (liver + muscle)

• inhibits glycogen phosphorylase via protein phosphatase
• induce glycogen synthase

Question 10

Glucagon and epinephrin inhibit glycogen synthesis via

Answer 10

Protein kinase A is a glycogen synthase inhibitor

Question 11

Glycogen bonds

Answer 11

a-(1,6) bonds

a-(1,4) bonds

Question 12

Glycogen in skeletal muscles

Answer 12

It undergoes glycogenolysis to glucose-1-P –>glucose 6-P which is rabidly metabolized during exercise

Question 13

Glycogen bonds

Answer 13

branches: a-(1,6) bonds
linkages: a-(1,4) bonds

Question 14

Glycogen in hepatocytes function

Answer 14

1. Storage

2. Glycogenolysis to maintain blood sugar at appropriate levels

Question 15

Glycogen phosphorylase

Answer 15

Cleaves glucose-1-P residues off branched glycogen until four remain before a branch point

Question 16

Glycogen enzymes

Answer 16

1. UDP-glucose pyrophosphorylase
2. Glycogen synthase
3. Branching enzyme
4. Glycogen phosphorylase
5. 4-a-D-glucanotransferase (debranching enzymes)
6. a-1,6-glucosidase (debranching enzymes)
7. α-1,4-glucosidase

Question 17

Glycogen building block

Answer 17

UDP-glucose

Question 18

UDP-glucose pyphosphorylase function

Answer 18

Glucose -1-P to UDP-glucose (to be ready for glycogen formation)

Question 20

glycogen - Branching enzymes - function and types

Answer 20

Makes linear glycogen

• 4-a-D-glucanotransferase
• a-1,6-glucosidase

Question 20

a-1-6-glucosidase function

Answer 20

Cleaves off the last glucose 1-P on the branch

Question 21

4-a-D-glucanotransferase function

Answer 21

Moves 3 glucose-Ps from the brunch to the linkage (leaves 1)

Question 22

Acid maltase

Answer 22

A small amount of glycogen is degraded in in lysosomes by a-1,4-glycosidase

Question 23

Limit dextrin

Answer 23

One to four residues remaining on a branch after glycogen phosphorylase has already shortened it

Question 24

Glycogen storage diseases | How many tyoes

Answer 24

12 types all resulting in abnormal glycogen metabolism and accumulation of glycogen within cells

Question 26

Glycogen storage disease type 1 / mode of inheritance

Answer 26

Von Gierke disease AR

Question 27

Glycogen storage disease type 2 / mode of inheritance

Answer 27

Pompe disease AR

Question 28

Glycogen storage disease type 3 / mode of inheritance

Answer 28

Cori disease AR

Question 28

Mode of inheritance of glycogen storage diseases type 1-4

Answer 28

AR

Question 29

Glycogen storage disease type 4 / mode of inheritance

Answer 29

McArble disease AR

Question 31

Von Gierke disease (type 1) pathophysiology

Answer 31

Glucose-6-phosphatase deficiency --> impaired gluconeogenesis and glycogenolysis

Question 32

Von Gierke disease (type 1) findings

Answer 32

1. Severe fasting hypoglycemia 2. Increased glycogen in liver 3. Increased blood lactate 4. Hepatomegaly 5. incdreased TG 6. increased Uric acid (Gout)

Question 33

Von Gierke disease (type 1) treatment

Answer 33

Frequent oral glucose/cornstarch | Avoidance of fructose and galactose

Question 34

Pompe disease (type 2) pathophysiology

Answer 34

lysosomal a-1,4-glucosidase with α-1,4-glycosidase activity (Acid maltase) deficiency

Question 34

Pompe disease (type 2) findings

Answer 34

1. Cardiomyopathy 2. hypertrophic cardiomyopathy 3. exercise intolerance 4. Systemic findings leading to early death

Question 35

Pompe disease (type 2) findings

Answer 35

1. Cardiomegaly 2. hypertrophic cardiomyopathy 3. exercise intolerance 4. Systemic findings leading to early death

Question 37

Cori disease (type 3) pathophysiology

Answer 37

a-1,6-glucosidase deficiency

Question 37

McArdle disease (type 4) pathophysiology

Answer 37

Skeletal muscle phosphorylase (myophosphorylase deficiency)

Question 38

Cori disease (type 3) findings

Answer 38

- Milder form of type 1 with normal blood lactate (and gluconeogenesis is intact) - Accumulation of limit dextrin-like structures in cytosol

Question 40

McArdle disease (type 4) findings / mechanism

Answer 40

1. Increased glycogen in muscle, but cannot break it down leading to painful muscle cramps 2. Myoglobinuria (red urine) with strenuous exercise 3. Arrythmia from electrolyte abnormalities 4. 2nd wind phenomenon noted during exercise due to increased muscular blood flow

Question 41

There any problem with gluconeogenesis in Cori disease?

Answer 41

No. It is intact

Question 42

It is useful for Glycogen storage disease diagnosis

Answer 42

Periodic acid-Schiff stain

Question 43

Skeletal muscle phosphorylase

Answer 43

Myophosphorylase

Question 44

blood glucose in McArdle disease

Answer 44

unaffected