Carbohydrate and Glycogen Metabolism

Question 1

What bonds does glycogen have?
What cells have glycogen?
Where does glycogen formation and degradation occur?
What is the difference in glucose in Liver/Skeletal mm?
Explain what happens with glycogen in the liver?`

Answer 1

A (1-4) (1-6)
all cells; specifically liver and skeletal
cytosol
S: for ATP L: for maintaining blood glucose.
In liver the glucose-6-phosphatese removes a phosphate from glucose-6-phosphate –> glucose leaves through GLUT 2

Question 2

Muscle cells can perform gluconeogenesis T/F
Muscles can perform glycogen synthesis T/F
Muscle cells have glucose-6-phosphatase & GLUT 2 T/F
Explain why red muscle cells are long lasting?

Answer 2

F
T
T - allows glucose export
They have good O2 supply and can perform OP creating lost of ATP- White mm. only lactase (2ATP)

Question 3

The non-reducing ends of glycogen are where glucose is ______.

What is the benefit of glycogen branching?
Where are the enzymes that degrade glycogen linkages.

Answer 3

added/removed (reducing - lower–first one)

can liberate glucose and build glycogen faster
intestinal mucosa amylose (strait A1-4), amylopectin (branched A1-6)

Question 4

Why doesn’t the body just store glucose?

Answer 4

*glucose is osmotically active - would need ATP to pump in against gradient. Glycogen does not change osmolarity (1 molecule)

Question 5

Amylose Chain Degradation!

Name (2) enzymes that break down the amylose chain?
What are the products of this enzymatic activity?
What is so good about this breakdown?
Where does glucose phosphatase stop?
Explain how the glucose-1-phosphatase is utilized?
What specifically happens in the liver?
Where modification of G1P to G6P this occur?

Answer 5

Glucose phosphatase; alpha-amylase (hydrolase)
Glucose-1-phosphate; disaccharide respectively (non- (P))
no ATP is utilized
4 units away from branching
G1P – Mutase –> G6P (enter glycolysis pathway (step 2)
**(P) is removed in liver –> glucose –>GLUT2 –> circ. cytosol

Question 6

Amylopectin Chain Degradation!

Name (1) enzymes that break down the amylopectin chain?
What are the (2) actions of this enzyme?
What is the product of this enzymatic activity?
What is so good about this breakdown?
Explain how the glucose is utilized (liver) (muscle)
Where modification of G6P to glucose occur?

Answer 6

de-branching enzyme
transferase (3 to amylose chain); glycosides (hydroxylase)
free glucose
No ATP
L: glucose transported circ. M: needs (P) –> glycolysis
endoplasmic reticulum

Question 7

Explain how glucose is modified from Glucose-6-P in LIVER; where?

Answer 7

Glucose-6-P enters endoplasmic reticulum; G6P removes phosphate. GLUT 7 (ER specific transporter) releases glucose to cytosol

Question 8

Glycogen Storage Disease

Type 1, 2, 3, 4, 5, 6,

Answer 8

1: Deficiency in glycogen-6-phosphatase (no glucose from liver)
2: Lysosomal Deficiency (lacks enzyme to break glucose)
3: Glycogen Debrancher missing.
4: 2: Liver glycogen phosphatase deficiency (CHECK)
5: Skeletal glycogen phosphatase deficiency