Control of blood glucose concentrationAQA A-Level Biology: Flashcards
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Name three processes in the liver that control blood glucose.
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- Name three processes in the liver that control blood glucose.
- Glycogenesis, glycogenolysis and gluconeogenesis.
- What is glycogenolysis?
- The hydrolysis of glycogen to glucose, which raises blood glucose concentration.
- What is gluconeogenesis?
- The production of glucose from glycerol and amino acids.
- How does insulin increase glucose uptake by a cell?
- It binds to receptors and increases the number of glucose channel proteins in the surface membrane.
- How does insulin affect enzymes in liver cells?
- It activates enzymes that convert glucose to glycogen.
- What does glucagon activate in liver cells?
- Enzymes converting glycogen to glucose, and glycerol and amino acids to glucose.
- What does adrenaline activate in liver cells?
- Enzymes that convert glycogen to glucose.
- What is the second messenger in the action of glucagon and adrenaline?
- Cyclic AMP (cAMP), produced from ATP by adenylate cyclase.
- What does cAMP activate?
- Protein kinase, which activates the enzymes that convert glycogen to glucose.
- What is the cause of type I diabetes?
- The (beta) cells of the pancreas do not produce enough insulin, often through autoimmune attack.
- What is the cause of type II diabetes?
- Target cells become less responsive to insulin (receptors lose responsiveness), linked to obesity and diet.
- How are type I and type II diabetes controlled?
- Type I by insulin injections; type II mainly by manipulating diet and exercise, sometimes drugs or insulin.
- Required practical 11: how do you find the glucose concentration of an unknown sample?
- Make a dilution series, react with Benedict's reagent, measure absorbance with a colorimeter, plot a calibration curve and read off the unknown, allowing for dilution.
Exam questions on Control of blood glucose concentration
- A healthy adult eats no food for 14 hours. During this time the concentration of glucose in her blood stays at about 4.5 mmol dm⁻³, even though no glucose is being absorbed from her gut. Her liver cells are responsible for much of this regulation.Glucagon is released when blood glucose concentration falls. State two ways in which glucagon increases the concentration of glucose in the blood.2 marks
- A researcher adds insulin to cultured muscle cells. Within minutes, the uptake of glucose by the cells increases, and the number of glucose channel proteins in the cell surface membrane is found to be greater than before. The concentration of glucose in the surrounding solution is the same throughout.Insulin also activates enzymes inside the muscle cells. Explain how this helps to increase the uptake of glucose.2 marks
- A clinic is testing the urine of two patients with diabetes: patient 1 has type I diabetes and patient 2 has type II diabetes. The clinic estimates glucose concentration using Benedict's reagent and a colorimeter with a red filter. Standard glucose solutions of 0.0, 0.2, 0.4, 0.6 and 0.8 mmol dm⁻³ gave absorbances of 0.90, 0.72, 0.54, 0.36 and 0.18, because less blue copper(II) remains as glucose concentration increases. A urine sample from patient 2 was diluted by mixing 1 cm³ of urine with 9 cm³ of distilled water, and the diluted sample gave an absorbance of 0.45.Explain why patient 1 needs insulin injections, but patient 2 may be able to control their blood glucose concentration by changing their diet.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).