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Criado por Charlotte Hewson
mais de 9 anos atrás
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Questão | Responda |
what is the cell surface membrane made up of? | phospholipid bilayer |
why are phospholipids important in the membrane? | -hydrophilic heads point inwards to the cytoplasm -the outer layer has hydrophilic heads pointing out to interact with water outside the cells -hydrophobic tail point to the centre of the membrane. |
what are the functions of the phospholipids? | -allow lipid soluble substances to enter and leave the cell -prevent water-soluble substances entering and leaving the cell -make the membrane flexible |
what are the 2 types of proteins found on the cell surface membrane? | extrinsic and intrinsic |
what do extrinsic proteins do? | give mechanical support or act as cell receptors for hormones |
where to extrinsic proteins occur? | on the surface or only partly embedded in it |
what are intrinsic proteins? | act as carriers to transport water-soluble molecules across membrane or are enzymes |
ere are they found? | span the bilayer from one side to the other |
what are the 6 main functions of these proteins? | -structural support -carriers transport water-soluble molecules -allow active transport though ion channels -recognition sites by identifying cells -help cells adhere -act as receptors |
why is it called a FLUID mosaic model? | individual phospholipids can move relative to each other. gives membrane a flexible structure and is constantly changing shape |
why is it called a fluid MOSAIC model? | the proteins embedded in the bilayer vary in shape, size and pattern so looks like a mosaic |
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