Energy storage

What is glycogenesis?

Synthesis of glycogen

What is Gluconeogenesis?

Synthesis is glucose from non-carbs

What is Glycogenolysis?

Breakdown of glycogen

What are the normal and diabetic levels of fasting plasma glucose ?

Normal:

<5.6 mmol/l and <7.8 mmol/l 2 hours after the test

Diabetic:

>7 mmol/l and >11.1 mmol/l after 2 hrs

Properties of glycogen

• Alpha 1,4 and 1,6 glycosidic bond

• Large branched molecule

• Low osmotic effect

• Stored in nucleus and live

Glycogenolysis pathway

(Glycogen phosphorylase) (Mutase)

Muscle glycogen → glucose-1-phophate → glucose-6-phosphate → glycolysis → ATP, CO2, lactate

(Glycogen phosphorylase) (Mutase) (Glucose-6-phosphatase)

Liver glycogen → glucose-1-phophate → glucose-6-phosphate → blood glucose

What is Von Gierke disease (glycogen storage disease) and what are the symptoms?

The body cannot breakdown glycogen due to deficiency in glucose-6-phosphatase → accumulation of glucose-6-phosphate

** autosomal recessive

Symptoms: hypoglycemia + lactic acidosis → seizures, hepatomegaly (distended abdomen) cerebral damage, doll like face

Where does gluconeogenesis occur?

In the liver and the kidney cortex

Occurs due to stress (fasting, exercise£

What are the importance enzymes in gluconeogenesis and what can stimulate and inhibit them?

PEPCK + fructose-1,6-bisphosphate

Stimulate: glucagon

Inhibit: insulin

Where does the body get energy after eating?

<2 hrs: glucose

8-10hrs: glycogenolysis

>10 hrs: gluconeogenesis

How does insulin stimulate glycolysis?

• increases the rate of glucose transport across the membrane

• Increases Hexokinase and 6-Phosphofructokinase activity

• Stimulates the rate of glycogen synthesis and decreases the rate of glycogen breakdown

What promotes and inhibits lipid storage?

Promote: insulin (inhibit HSL)

Inhibit: glucagon, adrenaline cortisol, GH (activate HSL)

How many molecules of ATP are produced in fatty acid oxidation ?

4 ATP per round

** occurs in mitochondria

Where and from what are lipids synthesised from ? (Lipogenesis)

In the cytoplasm of liver cells

Acetyl CoA from mitochondria is used

Requires ATP + NADPH

Lipogenesis vs lipolysis