Cell Membrane Flashcards
Define the ‘fluid mosaic model’
Fluid- molecules keep moving aroud
Mosaic- small parts arranged this way
What is the name for the membrane made of phospholipids?
Phospholipid bilayer
Name the chain of hexagonal molecules between phospholipids in the membrane.
Cholesterol
Name the molecule with a chain of hexagonal polymers on it.
Glycoprotein
Name the macromolecule that lies between phopholipids in the membrane.
Carrier protein.
Name the molecule which involves a hexagonal chain branching from a phosphate on the membrane.
Glycolipid
Name the protein that lies in only one layer of the phospholipid bilayer.
Extrinsic protein
Describe a phospholipid
- Hydrophilic phosphate head
- Hydrophobic fatty acid tail (two chains)
Functions of a membrane protein
- Enzymes
- Channels to allow ions/molecules through carrier proteins
- Receptors for hormones
What can diffuse across a plasma membrane?
- Hydrophobic molecules
- Small uncharged polar molecles
Main functions of cell membrane
- Protects cell
- Compartmentalisation
- Controls what enters and leaves
- Attachment site
- Folds to increase SA
- Isolation of harmful substances
Define diffusion
-Passive movement of a substance down a concentration gradient
Define facilitated diffusion
Passive movement of a substance down a conc. gradient with the help of a protein (e.g. carrier protein)
Define osmosis
Passive movement of water from an area of high water potential to an area of low water potential across a semi-permeable membrane
Define active transport
Movement of a substance against the conc. gradient across a membrane and requires energy
