Cell membranes 0.0 / 5 ? BiologyCell membranes TOPIC 2BASAQA Created by: ChartamaraCreated on: 08-02-16 20:20 What is the purpose of a cell membrane? To control which substances enter and leave the cell. 1 of 19 Name one way in which substances can move across a cell membrane? OSMOSIS, DIFFUSION OR ACTIVE TRANSPORT. 2 of 19 What are cell membranes made of? Lipids, proteins and carbohydrates. 3 of 19 Define a receptor protein. It is a protein in which allows cells to detect chemicals released from other cells. 4 of 19 Name a similarity between glycolipids and glycoproteins. They both have a carbohydrate attached to them 5 of 19 What is the model used to describe a cell membrane called? Fluid Mosaic model 6 of 19 Why does the centre part of a cell membrane not allow water-soluble substances to diffuse through it? Because the tails of phospholipids are hydrophobic and therefore are located in the centre. 7 of 19 What type of substances can diffuse through the hydrophobic tails of a phospholipid bilayer? Small, non-polar substances. 8 of 19 Why is cholestrol used in cell membranes? To give the membrane stability. 9 of 19 How does cholesterol provide stability? It binds to the tails of phospholipids, therefore causing them to bunch together and move less, this makes the membrane less fluid and more rigid. 10 of 19 How does cholestrol also help with the barrier against polar substances? It has hydrophobic parts. 11 of 19 How can temperature affect membranes? It affects how much phospholipids can move. 12 of 19 At which temperature would phospholipids lack energy? Temperatures below 0 degrees. 13 of 19 At temperatures below 0 degrees what is there a possibility of forming? Ice crystals 14 of 19 As the temperature increases between 0 and 45, what happens to the permeability of a membrane? It is increased. 15 of 19 Why is the permeability of a membrane increases when temperature increases from 0 to 45 degrees? Because phospholipids have more energy and can therefore move more. 16 of 19 At which temperatures does the phospholipid bilayer begin to break down? above 45 degrees. 17 of 19 Why is the membrane put under pressure at temperatures above 45 degrees? Because the water inside the cell expands. 18 of 19 Why is permeability increased at temperatures above 45 degrees? Because channel and carrier proteins denature so therefore cannot control substances leaving and entering the cell. 19 of 19
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