Review posters 14/05/2016 Flashcards
Process of glycogen synthesis
Glucogenesis
Process of glycogen synthesis from non-carbohydrate pre-cursors
Gluconeogenesis
Process of glycogen breakdown
glycogenolysis
Where is glycogen stored?
The liver and muscles
What is the difference between the two places glycogen is stored?
The muscle cell has to use to glycogen that is broken down there, whereas the liver can release it into the bloodstream.
When is glycogen broken down?
Between meal times.
How are blood sugar levels maintained?
Just after a meal- blood sugar levels are at their highest.
Also inbetween meals- glycogen is released to keep blood sugar levels up.
At times like breakfast when you haven’t eaten in a while- gluconeogenesis comes into play.
What is glucogenin and why do you need it?
Glycogen synthase cannot make glycogen without an existing chain being present. Therefore you need glucogenin which acts as a starting point at the centre of glycogen. It has catalytic activity which allows it to add small amounts of glucose onto it.
What is UDP glucose?
This is activated glucose. Urine disphosphate with a glucose attached to it. The bond between glucose and phosphate contains high energy- this is used to transfer glucose.
Glycogen synthase can introduce 1-6 branches. True or False
False
Which enzyme introduces branches into glycogen?
Branching enzyme
What catalyses glucogenolysis?
Glycogen phosphorylase
What is glycogen converted too in glucogenolysis?
Glycogen is converted too glucose-1-phosphate. This can then be converted into glucose-6-phosphate.
What happens in the liver in glucogenolysis?
Glucose-6-phosphate is dephosphorylated to glucose which can then be released into the blood via GLUT2.
What is the fate of glucose-6-phosphate in muscle?
It undergoes glycolysis and releases energy.
How is glycogenolysis stimulated and at which part of the cycle?
Adrenaline and cortisol stimulate glycogen phosphorylase.
Name the precursors used in gluconeogenesis
Lactate, amino acids and glycerol
Describe each of the precursors
Lactate- derived from anaerobic respiration
Amino acids- glucogenic amino acids. Derived from muscle protein.
Glycerol- from triglycerides in adipose tissue.
Describe gluconeogenesis
Extremely energy consuming making of new glucose.
Essentially the reverse of glycolysis- needs specific enzymes to get round the irreversible reactions.
Classes of amino acids
Ketogenic- can’t be used in gluconeogenesis
Glucogenic- can be used in gluconeogenesis
What happens to glucogenic amino acids?
They are either converted to pyruvate and then to glucose or enter the TCA cycle and are converted to oxaloacetate then glucose.
Hormonal regulation of gluconeogenesis
Glucagon - increases gluconeogenesis
Inhibits glycolysis
Insulin- decreases gluconeogenesis
Stimulates glycolysis
What occurs in the embryonic stage of lung development?
Respiratory diverticulum forms
Initial branching to give lung, lobes and segments
What occurs in the Psuedoglandular stage of lung development?
Formation of terminal bronchioles