1. Lesson starter 1.Give one similarity and one difference between diffusion and osmosis 2.Explain why water is described as a polar molecule.

2. Answers 1.Both are involved in movement from an area of high concentration to an area of low concentration / are passive / do not require ATP Osmosis refers to water molecules only, but diffusion refers to many different molecules and ions. 2. It has different areas of positive and negative charges.

3. Blood Glucose Learning objective outline how the concentration of glucose is measured in human blood describe the basic structure of carbohydrates, with reference to monosaccharides, disaccharides and polysaccharides; describe, with the aid of diagrams, the structure of the ring form of alpha glucose; outline the role of glucose as a respiratory substrate; describe the formation of glycogen by condensation reactions to form glycosidic bonds; describe how the structure of the glycogen molecule adapts it to its function as an energy store in liver and muscle;

4. Measuring blood glucose concentrations Blood glucose meters are becoming more commonly used to measure the concentration of glucose in the blood, especially for sufferers of diabetes mellitus. The test strip on the metre contains an enzyme – glucose dehydrogenase or glucose oxidase. The following reaction occurs: a small electrical current is initiated, which is detected by the test strip. Within 15-30 seconds, a reading is given out Glucose glucose oxidase/dehydrogenase gluconolactone

5. Measuring blood glucose concentrations To obtain a reading, the user must wash their hands thoroughly and swap the area to be tested with alcohol. A sterile lancet is used to prick the skin on top of their finger A small drop of blood is placed on a clean glucose test strip. This is then placed into the glucose test meter.

6. Measuring blood glucose concentrations The frequency of glucose blood testing depends on advice from the doctor and the type of diabetes the patient has, and how well it is controlled. Blood glucose is measured in millimoles per litre (mmol dm -3 ) Normal blood glucose = 4-8 mmol dm -3 Before meals = 4-7 mmol dm -3 Less than 10 mmol dm -3 90 minutes after a meal (elevated insulin levels for sustained periods of time can be dangerous) About 8 mmol dm -3 at bedtime

7. Monosaccharides Simple sugars that can be used as respiratory substrates. This means that is can be broken down directly during aerobic respiration to synthesise ATP. Glucose is very soluble, so it is easily transported in the blood plasma Alpha glucose is an example of a monosaccharide sugar that is found in blood Alpha glucose has the OH group on carbon 1 facing down, towards carbon 2c

8. Disaccharides Two monosaccharides joined up together make a disaccharide. Two glucose molecules joined make the sugar maltose. Glucose and fructose joined together make the sugar sucrose, which we commonly use in tea etc. These monosaccharides join together by condensation reactions and a glycosidic link is created.

10. Polysaccharides When many monosaccharides join together, a polysaccharide is formed (poly = many) In humans, many alpha glucose molecules joining up together forms the storage molecule glycogen A glycogen molecule looks branched because one glucose molecule (residue) can form glycosidic links with 3 other glucose molecules

11. Glucose monomer 1,6 glycosidic bond

12. Polysaccharides Glycogen is used for storage of energy. It is well suited to this role because: – It is insoluble so does not affect the water potential of cells – Compact- lots of glucose can be stored in a small space – Branching structure means there are lots of “ends” where glucose can be released easily and quickly when needed.

13. Plenary - Exam questions

14. Exam questions

15. Exam answers

16. How did you do? The exam questions are a self assessment tool. If you found these questions difficult, you have not understood (or done) the pre- reading/textbook questions. Be honest with yourself – are you working as hard as you can?!