Metabolic pathways: glycolysis Flashcards
How is glucose transported into cells?
Via Na+/glucose symporters
Via passive facilitated diffusion glucose transporters
What are the glucose tranpsorters in muscle and adipose tissue?
GLUT4
What is the significane of GLUT1 and GLUT3 having a low Km?
GLUT1 & GLUT3 facilitate glucose uptake in brain - low Km means glucose can still get into the brain when there are low concentrations
Why does GLUT2, the transporter for liver beta cells, have a high Km?
Beta cells use this to take up glucose to detect glucose levels
A high Km means this only happens when glucose concentrations are high
Therefore, the beta cells know to secrete insulin
How do glucose transporters work to allow glucose uptake into cells?
Binding of glucose to outside of the transporter triggers a conformational change and the transporter changes shape in order to allow glucose release to the inside of the cell
How many pyruvate molecules are derived from one glucose molecule?
2
How many ATP are needed to initiate glycolysis?
2
How many ATP are produced in glycolysis?
4
Is glycolysis an oxidative or a reductive pathway?
Oxidative
What is the significance of the reactions converting glucose to fructose-1,6,-bisphosphate?
Glucose has been trapped and destabilised, as well as phosphorylated
Why is phosphorylated glucose less likely than normal glucose to travel through membranes?
Because of the negative charge on the phosphate groups
What is the first control point of glycolysis?
Conversion of glucose to glucose-6-phoshate by hexokinase is inhibited by glucose-6-phosphate in a negative feedback reaction
What are the second and third control points of glycolysis mediated by?
ATP - inhibits these reactions (third and last reactions)
Signals that enough energy has been made
What is the enzyme that mediates the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate?
Phosphofructokinase
What enzyme is the main regulator of glycolysis?
Phosphofructokinase
