GI Flashcards
Glycogen synthase primer
Glycogenin (adds 4 glucose to itself)
3 irreversible pathways of glycolysis
- hexokinase (1)
- phosphofructokinase (3)
- pyruvate kinase (last)
Glucose to glucose-6-phosphate is catalysed by
Hexokinase
Glucose-6-phosphate to glucose-1-phosphate and vice versa is catalysed by
Phoshphoglucomutase
Glucose-1-phosphate to UDP glucose is catalysed by
UDP glucose phosphorylase
Rate limiting enzyme of glycogenesis
Glycogen synthase
Enzyme which adds branches to glycogen
Transglycosylase
Glycogenolysis catalysed by
Glycogen phosphorylase
Processes by which glycogen can be broken down by skeletal muscle
TCA cycle and glycolysis
Process by which glycogens broken down by liver
Glycogenolysis
How is glucose transported to blood?
GLUT2 transporter
The Cori cycle
Lactate-pyruvate-glucose
Location of gluconeogenesis
Liver (kidneys)
Effects of insulin and starvation on albumin levels?
Insulin increases, starvation decreases. Levels are low in liver disease
How can plasma proteins be separated?
Simple electrophoresis
What is ceruloplasmin?
Alpha protein
What type of protein is retinol binding protein?
Alpha protein, transports vitamin A
Function of alpha proteins?
Transport lipoproteins, lipids, hormones and bilirubin
Example of a beta protein
Transferrin, transports iron
Protein which is the main determinant of plasma oncotic pressure?
Albumin (water soluble and negatively charged)
Albumin levels in liver disease?
Low
Fatty acids, bilirubin and thyroid hormones are transported by what?
These endogenous lipophilic substances are transported by albumin. Albumin also transports exogenous substances i.e drugs like aspirin
How is iron stored in cells?
As ferritin
How is copper transported?
Bound to ceruloplasmin. Copper is needed for regulation of redox reactions and for transport/use of iron.
Are the steroid hormones and the T3/T4 hormones hydrophilic or hydrophobic?
Hydrophobic
How is thyroxine transported?
Thyroid-binding globulin (extended biological half life and increased plasma concentration)
How is cortisol transported?
Cortisol-binding globulin (extended biological half-life and increased plasma concentration)
Function of chylomicrons?
Transport of exogenous fat to liver
Function of VLDL?
Transport of endogenous fat to peripheral tissues
Function of IDL?
LDL precursor
Function of LDL?
Transport of cholesterol to peripheral tissues
Function of HDL?
Reverse cholesterol transport
What vitamins and metal can the iron store?
Vitamins A, D and B. Iron (stored associated with Ferritin)
How is vitamin A stored in the liver?
As retinol palmitate
What is needed to make vitamin D, steroid hormones and bile acids?
Cholesterol
Product of HMGcoA reductase?
Mevalonic acid
Dietary cholesterol and intrahepatocyte cholesterol reduce activity of what enzyme?
HMGcoA reductase
Which vitamin is important for regulation of calcium and phosphorus metabolism?
Vitamin D
What is the most abundant form of vitamin D in the circulation?
Vitamin D3
What steroid hormones are made from cholesterol?
Corticosteroids, androgens (testis), estrogens (ovary)
What converts primary bile salts into secondary bile salts?
Bacteria
What mmol/l is considered atherogenic for LDL?
above 4.1
What annoying molecules are needed for cholesterol synthesis?
18 mol acetyl coA
16 mol NADPH
36 mol ATP
Glycogen storage diseases
Glycogen stored in liver and muscle
How are bilirubin, fatty acids and thyroid hormones transported in the body?
Bound to albumin
Cholesterol is a precursor for which vitamin?
Vitamin D
Role of vitamin D?
Calcium and phosphate metabolism
What is the most abundant form of vitamin D in the body?
Vitamin D3
