1. Monday 20 th February 2012 Learning Objectives: What is haemoglobin? How is haemoglobin different in different organims? Keywords: Haemoglobin Ferrous Ion Oxygen Affinity Starter: Haemoglobin H/W:

2. Haemoglobin structure Primary – four polypepetide chains Secondary – each chain is coiled into a helix Tertiary – each chain is folded into a precise shape Quaternary – all four chains are linked together to form an almost spehrical molecule. Each polypeptide is associated with a haem group which contains a ferrous ion (Fe 2+ ) Each Fe 2+ ion can combine with a single O2 molecule Oxygen binding group

3. Role of haemoglobin To transport Oxygen efficiently To readily associate with Oxygen at the surface where gas exchange occurs To readily disassociate from Oxygen at thise tissues requiring it Haemoglobin is able to change its affinity for Oxygen under different conditions

4. Different haemoglobins An organism living in an environment will require a haemoglobin that readily combines with Oxygen An organism with a high metabolic rate needs to release Oxygen readily into its tissues Loading/associating – Lungs Unloading/dissociating - Tissues

6. Thursday 23 rd February 2012 Learning Objectives: What is an Oxygen dissociation curve? What is the effect of CO 2 on the curve? Keywords: Dissociation Ferrous Ion Oxygen Affinity Starter: Great affinity = Low affinity = Takes up oxygen less readily Releases oxygen easily Takes up oxygen readily Releases oxygen less easily Oxygen dissociation curves H/W:

7. Affinity High Takes up oxygen readily Releases oxygen less easily Low Takes up oxygen less readily Releases oxygen easily

8. Oxygen dissociation curve The partial pressure of gas is measured in kiloPascales (kPa) This is how much gas is present in a mixture of gas The partial pressure of Oxygen is written pO 2 The 1 st Oxygen molecule is very hard to be taken up However once it is absorbed by haemoglobin the 2 nd, 3 rd and 4 th absorb a lot quicker The haemoglobin becomes saturated

9. Oxygen dissociation curve The further LEFT the curve the higher the AFFINITY for Oxygen In low CO 2 concentration The further RIGHT the curve the lower the AFFINITY for Oxygen In high CO 2 concentration LUNGS MUSCLES

10. Loading and unloading of Oxygen High rate of respiration The more CO 2 produced by tissues The lower the pH The more the shape of haemoglobin changes The more readily Oxygen is unloaded The more Oxygen is available for respiration

11. The lugworm Remember the environment determines the type of haemoglobin an organism has The levels of Oxygen Shinal & Thaposhi – Q’s 1-2 Mayward & Tahira – Q’s 3-4 Lydia & Stephanie – Q’s 5-6 Sayma, Natalie & Maria – Q’s 7-8 Faizaa & Soroya – Q’s 9-10 Keira & Almas – Q’s 11-12

12. Homework On a sheet that I can collect in separately to your notes All the summary questions on page 155 Due in tomorrow!

13. Friday 24 th February 2012 Learning Objectives: How are α–glucose monomers arranged to form polymers? How is structure related to function? Keywords: Condensation Osmosis α-glucose β-glucose Starter: Draw an a-glucose molecule Starch, glycogen and Cellulose H/W:Due in today!!

14. a-glucose

15. Starch Polysaccharide found in many parts of a plant Major energy source in most diets Many α-glucose monomers linked by glycosidic bonds Condensation reaction Unbranched structure means it can coil tightly This makes it very compact

16. Energy storage Insoluble Water is not drawn into cells by osmosis Does not easily diffuse out of cells Compact – a lot can be stored in a small space When hydrolysed it forms α-glucose which is easily transported and readily used in respiration

17. Glycogen Starch is found in plants only The animal equivalent is Glycogen Has shorter chains Is more highly branched Stored in the muscles and the liver It’s structure is suitable for storage in the same way as starch It is even more readily hydrolysed to α-glucose because it has shorter chains

18. Cellulose Made from monomers of β-glucose The position of the –H and the –OH group on a single Carbon atom is reversed The –OH group is above rather than below the ring What implications does this have when forming polymers? It has to rotate 180° to form a glycosidic bond

19. Cellulose Each β-glucose must be rotated 180° to its neighbour in order to form a glycosidic link The CH 2 OH group alternates above and below the chain Straight unbranched chain Parallel to each other Hydrogen bonds form cross-linkages between adjacent chains The sheer overall number of hydrogen bonds contribute to strengthening cellulose It is a structural material

20. Comparing polysaccharides StarchGlycogenCellulose MONOMERS Structure 1 – Function 1 - Structure 2 – Function 2 -

23. Monday 27 th February 2012 Learning Objectives: What is the structure of palisade cells? How do plant cells and animal cells differ? Keywords: Eukaryote Chloroplasts Grana Thylakoid Starter: List as many different parts of a plant cell Plant cell structure H/W:

24. Leaf palisade cell To carry out photosynthesis Long and thin to form a continuous layer Numerous chloroplasts in the best position to absorb maximum sunlight Large vacoule that pushes cytoplasm and chloroplasts to the edge

25. Chloroplasts Approx 2-10 μm long and 1 μ m in diameter Chloroplast envelope – double plasma membrane. Highly selective Grana – stacks of up to 100 thylakoids Thylakoid – contains the photosnthetic pigment chlorophyll. The 1 st stage of photosynthesis Stroma – fluid-filled matrix where the 2 nd stage of photosythesis takes place

26. What’s the difference? Plant cells Cellulose cell wall Chloroplasts are present Normally has a large, single, central vacuole filled with cell sap Starch grains are used for storage Animal cells Only a cell-surface membrane Chloroplasts are never present If vacuoles are present they are small and scattered Glycogen granules are used for storage

27. Adapted to function Granal membranes – The stroma – Chloroplasts – Cell walls are made of cellulose which give it great strength due to the microfibrils Provide mechanical strength to prevent the cell bursting under pressure Allows water to pass through it