Flashcards in Structure and function of membranes Deck (18):
What do membranes do?
-Separate contents of cells from their environment.
-Separate different areas within organelles.
What are the functions of membranes within cells?
-Site of chemical reactions.
-Control what substances leave and enter organelles.
What is the plasma membrane?
-Cell surface membrane which separates cell from the external environment.
What are membranes formed from?
What is the structure of the phospholipid bilayer?
-Hydrophilic phosphate heads point outwards and fatty acid hydrophobic tails point inward to form a hydrophobic core.
Are phospholipids soluble?
-Soluble because the heads can interact with water.
What is the fluid mosaic model?
-Phospholipids are free to move within bilayer which gives the membrane flexibility and shape.
What are the main components of a cell membrane?
-Phospholipid bilayer consisting of hydrophobic tails and hydrophilic heads.
-Extrinsic and intrinsic proteins.
What are intrinsic proteins?
-Proteins embedded through both layers in the membrane.
-Have amino acids with hydrophobic R-groups on external surfaces which interact with hydrophobic core in membrane.
What are examples of intrinsic proteins?
What are channel proteins?
-Provide hydrophilic channel that allows diffusion of ions through membrane.
-Held in position by interactions between hydrophobic core and hydrophobic R-groups in protein.
What are carrier proteins?
-important role in passive and active transport into cells.
-Involves change of protein shape.
What are glycoproteins?
-Embedded in membrane with attached carbohydrate chains.
-Play a role in cell adhesion and as receptors for chemical signals. Also, cell signalling.
What are glycolipids?
-Lipids with attached carbohydrate chains.
-Cell markers and can be recognised by immune system.
What are extrinsic proteins?
-Proteins present in one side of the bilayer.
-Have hydrophilic R-groups on external surface and interact with polar heads of phospholipid.
What is cholesterol?
-Lipid with a hydrophobic and hydrophilic end.
What is the role of cholesterol?
-Regulates fluidity of membrane.
-Adds stability to membrane.