Glycogen

Question 0

How many reducing ends does glycogen have?

Answer 0

1

Question 1

Where is glycogen cleaved?

Answer 1

Non-reducing ends

Question 2

What two types of bonds does glycogen have? Which is branching?

Answer 2

Alpha 1,4 and Alpha 1,6 (branch)

Question 3

What are the three benefits to storing energy in glycogen?

Answer 3

Can be rapidly mobilized, can be used under anaerobic conditions, and can convert to glucose to maintain blood homeostasis

Question 4

Where is the majority of glycogen stored?

Answer 4

Liver and muscle

Question 5

What is the shape of glycogen?

Answer 5

Granules (highly branched)

Question 6

Where are glycogen synthesis/degredation taking place?

Answer 6

Cytosol

Question 7

Follow the degradation of glycogen

Answer 7

Glycogen to glucose-1-P via debracnhing enzyme and glycogen phosphorylase. G1P to G6P via phsophoglucomutase. G6P to glucose via glucose-6-phosphatase (liver only)

Question 8

Glycogen linear chains are broken down to what?

Answer 8

Glucose 1-P via glycogen phosphorylase

Question 9

What is phosphorylytic cleavage? Where does it happen in glycogen degredation?

Answer 9

Glycogen to G1P, uses phosphorus instead of water to cleave a bond

Question 10

Describe the function of the branching enzyme

Answer 10

When linear chain is down to 4 glucose molecules, 3 are removed and added to the longer chain and 1 free glucose molecule is released.

Question 11

T or F: For every 8 glucose molecules in glycogen taken to G1P, 1 free glucose molecule is released

Answer 11

T

Question 12

What is the function of phosphoglucomutase?

Answer 12

G6P to G1P

Question 13

T or F: Glycogen degredation is the same in liver as it is in muscle

Answer 13

T

Question 14

Gylcogen is synthesized by taking G1P to?

Answer 14

UDP glucose via UDP glucose pyrophosphorylase

Question 15

UDP Glucose requires what energy?

Answer 15

2 ATP, release of pyrophosphate pulls the reaction toward products

Question 16

T or F: G6P and G1P are interchangeable

Answer 16

T via phosphoglucomutase

Question 17

What is the core protein at glycogen synthesis?

Answer 17

Glycogenin

Question 18

What residue is the beginning of glycogen on a glycogenin protein?

Answer 18

Tyrosine. The OH is super important for esterification

Question 19

How is UDP-glucose made into glycogen?

Answer 19

Via glycogen synthase which puts glucose on the chain and removes UDP

Question 20

What forms branches in glycogen? What are the requirements?

Answer 20

Branching enzyme, need at least 4 residues between each branch point (takes glucose chains from the end of a linear branch and adds on to glycogen granule)

Question 21

In glycogen formation, the anomeric carbon is attached to?

Answer 21

Glycogenin

Question 22

What happens to glycogen when cAMP cascade is activated?

Answer 22

PKA is activated which P glycogen inactivating it, and Ps Glycogen phosphorylase kinases which then Ps glycogen phosphorylase to activate degredation

Question 23

Describe low blood sugar effect on glycogen in liver

Answer 23

Low Blood glucose release glucagon insulin goes down then cAMP activated which causes PKA to inactivate glycogen synthetase (Ps it) and Ps glycogen phosphorylase kinase which Ps glycogen phosphorylase activating glycogen degredation

Question 24

What is the purpose of glycogen phosphorylase kinase?

Answer 24

To activate a bunch of glycogen phosphorylase, makes it very rapid versus a 1:1 activation by PKA

Question 25

What is the regulator of Glycogen synthesis? Degredation?

Answer 25

Glycogen synthetase; Glycogen phosphorylase

Question 26

What happens to glycogen in the liver in the presence of insulin?

Answer 26

cAMP is deactivated, Glycogen synthetase is dephosphorylated and activated whereas GPK and glycogen phosphorylase are dephosphorylated and made inactive

Question 27

Where does the liver get ATP from?

Answer 27

Typically from adipose

Question 28

Where does the energy for gluconeogenesis in the liver come from?

Answer 28

Fat

Question 29

How does fat provide energy to liver?

Answer 29

FA and glycerol are brought to liver and broken into acetyl CoA for energy synthesis

Question 30

Free glucose can be released from liver and generally not from the muscle, why?

Answer 30

Liver has glucose-6-phosphatase and muscle does not (releases one per debranching enzyme potentially however)

Question 31

Ephinephrine on muscle does what in regards to glycogen?

Answer 31

Activates cAMP cascade and so on to activate glycogen phosphorylase and inactivate glycogen synthetase

Question 32

What binds to liver in order to tell liver to release glucose via gluconeogenesis?

Answer 32

Ephinephrine and glucagon

Question 33

T or F: Epinephrine is stronger than insulin and can overwhelm glycogen synthesis when competing

Answer 33

T; think fight or flight

Question 34

P glycogen synthetase is?

Answer 34

Inactive (in liver and muscle)

Question 35

P glycogen phosphorylase is?

Answer 35

Active (in liver and muscle)

Question 36

What regulates glycogen synthetase?

Answer 36

Positive: Glucose 6-P Negative: phoshphorylation

Question 37

What regulates Glycogen phosphorylase?

Answer 37

Negative: ATP, Glucose 6 P, Glucose in liver Positive: AMP in muscle, phosphorylation

Question 38

T or F: GLUT-4 is in the liver

Answer 38

F; it is only in muscle insulin dependent

Question 39

Insulin is a universal signal for?

Answer 39

Energy storage (glycogen or as fatty acid)

Question 40

Glycolysis happens in the liver primarily for?

Answer 40

FA synthesis

Question 41

Von Gierke Disease is?

Answer 41

Mutation in G6Phosphatase leading to hypoglycemia and enlargement of the liver

Question 42

Pompe disease is?

Answer 42

Alpha 1,4 glucosidase lysosomal disorder leading to heart failure

Question 43

What is Cori disease?

Answer 43

debranching enzyme is defective leading to Von Gierke type symptoms but less severe

Question 44

What is Andersen disease?

Answer 44

Branching enzyme is defective leading to cirrhosis of liver and early death

Question 45

What is McArdle diesease?

Answer 45

Phosphorylase is defective leading to muscles not getting energy and not functioning under strain. Only in muscle

Question 46

What is Hers disease?

Answer 46

Phosphorylase is defective in liver leading to inability to break down glycogen (does not affect gluconeogenesis)