Lecture 16B

Question 1

The end a free anomeric carbon is the ____.

Answer 1

Reducing End

Question 2

Polymeric form of glucose that is found in special granules primarily in the liver and skeletal muscles of mammals.

Answer 2

Glycogen

Question 3

May represent up to 10% f the weight of the liver and 1-2% of the weight of skeletal muscle.

Answer 3

Glycogen

Question 4

True-False; Storage of glycogen reduces the concentration of glucose from 400 mM to 0.01uM

Answer 4

True

Question 5

____ glycogen can be exhausted in less than an hour during a vigorous workout;
____ glycogen can last 12-24 hours.

Answer 5

Muscle

Liver

Question 6

Glycogen Breakdown requires which 3 enzymes?

Answer 6

Glycogen Phosphorylase
Glycogen Debranching Enzyme
Phosphoglucomutase

Question 7

Which enzyme removes glucose residues from the non-reducing ends of glycogen via attack by inorganic phosphate?

Answer 7

Glycogen Phosphorylase

Question 8

Which enzyme produces Glucose-1-phosphate?

Answer 8

Glycogen Phosphorylase

Question 9

Energy of the glycosidic bond is preserved by the formation of a

Answer 9

Phosphodiester Bond

Question 10

Why does direct production of G6P not occur?

Answer 10

It would not result in hydrolysis of a glucose residue from the glycogen chain and it is energetically unfavorable.

Question 11

Glycogen residues are removed from glycogen by

Answer 11

Glycogen phosphorylase

Question 12

Pyridoxal phosphate is a cofactor with which enzyme?

Answer 12

Glycogen Phosphorylase

Question 13

Glycogen Phosphorylase works on _____ ends until it reaches four residues from an (__ ->__) branch point.

Answer 13

non-reducing

alpha 1->6

Question 14

Transfers a block of 3 residues to the non-reducing end of the chain.

Answer 14

Debranching enzyme

Question 15

Cleaves the single remaining alpha 1->6 linked glucose

Answer 15

Debranching Enzyme

Question 16

Glucose 1- Phosphate is converted to G6P by

Answer 16

Phosphoglucomutase

Question 17

This enzyme first generates G16P then G6P in a freely reversible reaction

Answer 17

Phosphoglucomutase

Question 18

Phosphoglucomutase acts on which Amino Acid Residue?

Answer 18

Serine

Question 19

G6P enters glycolysis in order to produce for muscle contraction in which organ?

Answer 19

Muscle

Question 20

G6P is dephosphorylated by G6Phosphatase to produce glucose which is then exported to the blood stream. Which organ does this happen in?

Answer 20

Endoplasmic Reticulum

Question 21

What leads to glycogen storage disease?

Answer 21

Genetic defects is G6Pase or T1 (specific transporter)

Question 22

G6P is dephosphorylated in the ___ for transport out of the ____.

Answer 22

liver

liver

Question 23

G6P is transported into the liver via and out of the liver by.

Answer 23

T1 (into liver)

T2 (out of liver)

Question 24

What is the T3 transporter used for?

Answer 24

Phosphate out of the liver

Question 25

Many anabolic reactions involving sugars require them to be activated. Most often this requires attachment to ___.

Answer 25

UDP

Question 26

Is the formation of UDP reversible or irreversible?

Answer 26

Irreversible; due to subsequent hydrolysis of PPi

Question 27

What is the good leaving group, making nucleophilic reactions very favorable?

Answer 27

Nucleotidyl Group

Question 28

___ is the starting point for glycogen synthesis.

Answer 28

G6P

Question 29

G6P is then converted to ___ by ___.

Answer 29

G1P | Phosphoglucomutase

Question 30

___ converts G1P + UTP -> UDP-glucose and PPi

Answer 30

UDP-glucose pyrophosphorylase

Question 31

Glycogen synthase requires a primer of at least 8 glucose residues joined in a

Answer 31

alpha 1 -> 4 linkage

Question 32

Glycogen Synthesis primer is supplied by

Answer 32

Glycogenin

Question 33

Glycogen covalently attaches a glucose residue to

Answer 33

Tyr-194 residue

Question 34

Glycogenin then forms a tight complex with glycogen synthase and the nascent chain is extended by up to 7 more residues by _____.

Answer 34

Glycogenin

Question 35

Glycogen synthase begins to extend the chain, eventually disassociating from ____.

Answer 35

Glycogenin

Question 36

Glycogenin remans buried within the glycogen molecule, covalently attached to the ______.

Answer 36

single reducing end

Question 37

Branches are formed by ____ enzyme, which transfers 6 or 7 glucose residues from the nonreducing end of a glycogen chain containing at least 11 glucose residues to a C6 hydroxyl group of an interior residue.

Answer 37

Glycogen-Branching Enzyme

Question 38

Glycogen regulations occurs primarily through which 2 enzymes?

Answer 38

Glycogen Phosphorylase/Glycogen Synthase

Question 39

This enzyme is regulated allosterically and hormonally. It exists in 2 interconvertible forms.

Answer 39

Glycogen Phosphorylase

Question 40

What is the inactive form of Phosphorylase?

Answer 40

Phosphorylase B

Question 41

How is Phosphorylase converted to the active form?

Answer 41

Phosphorylase A; phosphorylation

Question 42

How is phosphorylation regulated?

Answer 42

Hormonally

Question 43

Glucose is an ____ inhibitor of the liver enzyme.

Answer 43

Allosteric

Question 44

Phosphorylase B predominates in ____, but epinephrine triggers phosphorylation to the a state.

Answer 44

resting muscle

Question 45

Phosphorylation state of glycogen phosphorylase is controlled by

Answer 45

Phosphorylase B Kinase

Question 46

Phosphorylase B Kinase is controlled by _____ or ___- via signaling cascade involving the 2nd msgr cAMP.

Answer 46

Glucagon | Epinephrine

Question 47

The enzyme cascade induced by cAMP allows for tremendous amplification of the

Answer 47

initial signal

Question 48

_____ converts phosphorylase a to the inactive b form once the extracellular signal is removed.

Answer 48

Phosphoryla a phosphatase (pp1)

Question 49

Which 2 allosteric activators contribute to glucose release.

Answer 49

Ca -> activates phosphorylase b by promoting conversion to the a form AMP -> acts as an allosteric activator to the a form

Question 50

Active form of glycogen synthase is ___.

Answer 50

unphosphorylated

Question 51

Dephosphorylation is catalyzed by _______, which is part of the glycogen particle.

Answer 51

Phosphorylation phosphatase-1

Question 52

Which 2 enzymes are regulated by phosphorylation-dephosphorylation cycle and are never fully active simultaneously.

Answer 52

Glycogen Synthase | Phosphoprotein phosphatase-1

Question 53

Phosphorylation states are regulated by the hormones ___ and ___.

Answer 53

insulin | glucagon

Question 54

Insulin is released by the ___ and influences glucagon synthase and breakdown via a signaling cascade that involves numerous phosphorylation events.

Answer 54

Pancreas

Question 55

Insulin increases glucose into the

Answer 55

Muscle

Question 56

Insulin stimulates the activity of muscle

Answer 56

Hexokinase

Question 57

Insulin activates

Answer 57

Glycogen Synthase

Question 58

Increased hexokinase activity enables activation of

Answer 58

Glucose

Question 59

Glycogen synthase makes glycogen for

Answer 59

energy storage

Question 60

What is the well fed state?

Answer 60

High blood glucose

Question 61

During the well fed state, what hormone is released? and and what is inactivated and what is activated

Answer 61

Insulin Inactivated -> GSK3 Activated -> PP1 (Glycogen synthase)

Question 62

What transporters are used during the well fed state?

Answer 62

GLUT2; increase in glucose concentration activates hexokinase, making G6P for glycogen synthesis

Question 63

During the fasting state, which hormone is activated?

Answer 63

Glucagon

Question 64

Which enzymes are activated and inactivated during the well-fed state?

Answer 64

Activated -> PKA and Glycogen Phosphorylase Inactivated ->Glycogen Synthase

Question 65

What is the end result in a fasting state?

Answer 65

Increase blood glucose levels via Glucagon; | Activate glycogen phosphorylase and inactivate glycogen synthase

Question 66

Gluconeogenesis is also activated during which state? fasting or well fed?

Answer 66

Fasting

Question 67

Gluconeogenesis is also activated by a decrease in

Answer 67

F26BP

Question 68

Glycolysis is inactivated by inactivation of

Answer 68

Pyruvate Kinase

Question 69

Control of carb metabolism in the liver vs. the muscle; | What is the difference?

Answer 69

In the liver, Glucose 6P goes to the blood glucose; Pyruvate always goes to Glucose 6P In the muscle, Glycogen -> Glucose 6P -> Pyruvate

Question 70

In which organ system does G6P get converted to Pyruvate?

Answer 70

Muscle