 Objectives  To learn the structure of the cell membrane  To learn how structure and function of the cell membrane are linked  To learn about different forms of transport across the cell wall.

 Cell is bound by a fluid membrane  It regulates movement of chemicals in and out of the cell;  It is involved in recognition and identification  It facilitates the function of the cell  It protects the cell  It keeps the cell together  It interacts with the membranes of other cells

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 1 A phospholipid bilayer which allows the passage of lipids across the membrane  2. Bilayer of phospholipid molecules with water loving heads on the inner and outer surface and water hating tails pointing into the membrane.  We describe our understanding of it as the ‘Singer and Nicholson’ fluid mosaic model.

 Included in the phospholipid bilayer are:  Integral proteins (carrier proteins)  Peripheral proteins  Cholesterol  Carbohydrate chains  Glycolipids (lipids with attached carbohydrate chains)  Glycoproteins (proteins with attached carbohydrate chains)  These inclusions can move around the fluid phospholipid bilayer.

 Carbohydrate chains  Give the cell a sugar coat or glycocalyx which protects the cell.  These carbohydrate chains are unique to individuals, tissue types and blood groups.  They are what our immune system uses to recognise our cells and invading ones.

 Allows rapid movement of carrier proteins around;  Gives flexibility to cells, so e.g. your nerve cells don’t crack when you bend.  Membrane proteins move freely.  Has been demonstrated by merging human and mouse cells. In 40 minutes membrane proteins from two cells completely mixed.

 Channel proteins: allow molecules to move across the membrane through a channel;  Carrier proteins: combine with chemicals to transport them across the membrane;  Cell recognition proteins are glycoproteins which allow us to recognise our own cells and invaders and therefore facilitate an immune response.

 Receptor proteins: Have a shape that allows one type of molecule to bind to it.  Once the molecule is bound to it, it changes shape altering the properties of the cell.  E.g. insulin binding to liver cells causes them to store sugar.  Enzymatic proteins carry out metabolic functions.

 1. make a model of the plasma membrane  2. Explain how your model shows its different parts and functions  3. Marking rubric same as for cell model.

 Known as cell transport covers the movement of substances in and out of the cell membrane.  Will include both the different types of transport  And the structure and function of the cell membrane

 E.g. H 2 O, CO 2 and O 2 in and out of the cell.  What is diffusion?  8ZRMI 8ZRMI  Across the cell membrane it is helped by protein  DRTQw DRTQw  This is called facilitated diffusion  An idea of random particle movement:

 1. It happens because of the natural movement of the particles of liquids and gases;  2. It does not need an organism to use energy;  3. It can only happen down a concentration gradient from higher to lower concentrations;  4. Across cell membranes it is assisted by carrier proteins.

 The diffusion of water across a semi- permeable membrane;  QEc QEc  Important in enabling plant cells to absorb water to maintain their turgor pressure;  Results in dilution of the solution  Water moves from weak solutions where there is lots of water to strong solutions where there is less water.  Does not require energy  Does require semi-permeable membrane.

 Hypotonic solution is weaker than the solution in the cell;  Isotonic solution is equal to that in the cell;  Hypertonic solution is stronger than that in the cell;  Lysed means split  Turgid means full and firm  Flaccid means limp, droopy  Plasmolysed means cell membrane and contents have shrunk away from the cell wall in plants.

 This does not require energy  All chemicals pass down a concentration gradient.  It is necessary for the transport of materials like glucose and some amino acids across the cell membrane because they are not lipid soluble;  It uses carrier molecules which are proteins crossing the cell membrane  Each carrier molecule is specific to one molecule to be transported  Open this simulation and try to show what is happening in a cell in different osmotic conditions

 This does require energy  RqzzL4 RqzzL4  To summarise both facilitated and active transport.  OvxXg9M&NR=1 OvxXg9M&NR=1

 endocytosis & exocyctosis are ways to transport large molecules across a membrane  In some cases, receptor sites on the surface of the cell bond with the large molecule  Endocytosis takes in material from the cell by pockets or in-foldings of the cell membrane itself this happens by phagocytosis (solids) & pinocytosis (liquids)

 release of large amounts of material from the cell The membrane of the vacuole surrounding the material joins with the cell membrane, forcing the contents out of the cell.  Large amounts of water may be removed from a cell in this way.

 type of endocytosis  this means “eating cell”  cytoplasm surrounds a particle & package it within a food vacuole  next, the cell engulfs it (surrounds it) Amoebas use this to take in their food  this uses A LOT of energy= form of active transport  G7mrw&feature=related G7mrw&feature=related

 the taking up liquid from a cell’s surrounding environment  tiny pockets form along the cell membrane, fill with liquid, and pinch off to form vacuoles within the cell  vitamins, nutrients and hormones may be absorbed into a cell using pinocytosis

 The sodium potassium pump.  Wig1vOnY Wig1vOnY  Watch the video and write your own voice over. You may work in pairs. Submit video with your voice over recorded.

 Describe the structure of the plasma membrane.  Say how its structure affects the transport of materials across it.  Think about how chemicals are imported and exported from the cell.  Describe how the structure of the cell membrane allows other functions.  You must also describe the types of transport and say which parts of the cell membrane they use and how they actually occur. Give examples of each.  ¼ of a mark to be deducted for each mistake spelling technical words up to 2 marks  ½ marks deducted for each time sentences are not correctly separated with punctuation or joined appropriately and meaningfully – up to 2 marks.  All information must be referenced. You may quote sections of articles but must show this with quotation marks and you must reference the information in the text. Minimum length 1000 words.  You must include labeled diagrams (2 marks). Content 14 marks  (total 20marks)