Lecture 9: Integration of Metabolism Flashcards
Show how glucose-6-phosphate is at the heart of glucose metabolism.
Show how acetyl CoA and pyruvate are at the heart of metabolism in the cell.
Give the effects of Glucagon on Blood Glucose.
Give the effects of Insulin on blood glucose.
Give detail of the glucose transporters.
Liver: Glut 1 - not dependent upon insulin, bidirectional (in/out of liver easily)
Muscle, Adipose tissue: Glut 4 - insulin dependent, transporter is presynthesised but stays in the ER and only goes to cell surface when insulin is released
Which hormone receptors are there in muscle?
Insulin receptors (no glucagon or adrenaline receptors)
Give two examples when there is cooperation of tissues.
Cori cycle and glucose-alanine cycle
Describe what happens in the Cori Cycle.
Rapidly contracting muscles need lots of ATP, which is provided when glucose undergoes glycolysis. In anaerobic conditions, lactate is produced. The lactate leaves the muscle and travels via the bloodstream to the liver, where it undergoes gluconeogenesis to regenerated glucose. There is a 6 ATP cost to the liver in the process. The glucose then travels to the muscle in the blood for more glycolysis to provide more ATP.
What happens in the glucose-alanine cycle?
Rapidly contracting muscles need lots of ATP, which is produced when glucose undergoes glycolysis to produce pyruvate. If oxygen is available, oxidation of amino acids, especially branched chain ones (valine, isoleucine, leucine) can lead to a high concentration of glutamate available for transamination, which adds an amino group to pyruvate to give alanine. Alanine then leaves the muscle and travels to the liver via the bloodstream. In the liver, the a amino group is removed from alanine and given to a-keto glutarate, which becomes glutamate. In this reaction alanine becomes pyuvate. Pyruvate then undergoes gluconeogenesis, regenerating glucose and costing the liver 6 ATP. The glucose is then transported back to the muscle, where it can undergo glycolysis and provide more ATP.
What is metabolic labelling?
Metabolic labelling is a key technique for stuing metabolism (and other important parts of biochemistry including the secretory pathway, transport of proteins through the ER, etc.). It use radioactive isotopes, such as 14C, 3H, 32P and 35S to label molecules so that their fate i cells and organisms can be followed.
Describe the two kinds of metabolic labelling.
The two types of metabolic labelling are universal and specific labelling. Universal labelling involves radioactively labelling every carbon in the molecule and specific labelling involves labelling one specific carbon. A carbon is labelled by being replaced with the radioactive isotope.
