Cell Surface Membrane Flashcards
Define membranes?
Flexible and able to break and fuse easily (phagocytosis). They allow cellular components to have different conditions.
What are cell membranes made of?
Phospholipids.
What do phospholipids form when in water?
Micelles.
What makes up the phospholipid bilateral?
A hydrophobic tail and hydrophilic head. * * * || || || || || || * * *
What makes a phospholipid?
A phosphate head, a glycerol and 2 fatty acid tails.
What is the cell surface membrane?
The plasma membrane that surrounds cells and form the boundary between the cytoplasm and the environment. Both eukaryotic and prokaryotic cells have an outer cell membrane.
What is the CSM described as?
It’s described as a fluid mosaic model, the arrangement of it causes this as the phospholipids can move relative to one and another (fluid) and the proteins can vary in size and shape but they still fit together (mosaic).
What are the functions of phospholipids?
- to allow lipid soluble molecules to enter and leave the cell
- to prevent water soluble molecules entering or leaving the cell
- make the membrane flexible and self sealing.
Why can some molecules move through the phospholipid bilayer?
Most molecules can’t move freely because they are not soluble in lipids so can’t pass through the bilayer, or they are too large to pass through the channels or they are of the same charge as the protein carrier therefore are repelled.
What is the cell surface membrane made of?
A phosphate head, fatty acid tails, channel proteins, cholesterol, intrinsic proteins, extrinsic proteins, glycoprotein, glycosidic and a carbohydrate branch.
What’s the phosphate head?
They point to the outside of the cell and are hydrophilic
What’s the fatty acid tail?
They point to the centre of the membrane and are hydrophobic.
What’s a glycoprotein?
They act as cell surface receptors, more specifically for hormones and neurotransmitters. It’s functions are to act as recognition sites, help the cells attach to one another (protein to protein) to form tissues and allows cells to recognise one another e.g. Lymphocytes.
What’s a glycolipid?
Made of a carbohydrate bonded to a lipid. The carb extends out of the bilayer and acts as a receptor for specific chemicals e.g. blood. They act as recognition sites, helps to maintain stability, helps cells attach to each other to form tissues and attaches to proteins.
What’s an intrinsic protein?
Some are protein channels which form water filled tubes to allow water soluble ions to diffuse across the membrane. Others are carrier proteins that bind to ions or molecules like glucose then change shape to move the molecules across the membrane. They go in and out.
