| What is meant by partially permeable membrane? | allows substances through but not all |
| How can substances move across a membrane? | through diffusion, osmosis, active transport |
| When is the term plasma membrane used? | when talking about the membrane on the outside of a cell |
| Outline the importance of the plasma membrane | Acts as a barrier between the cells and its environment and controls which substances enter and leave the cell. |
| Outline the key roles for membranes within cells with examples | - membrane around organelles divides the cell into different compartments. |
| Role of cholesterol | - gives membrane stability
- they bind to the hydrophobic tails of the phospholipids, causing them to pack more closely together making the membrane less fluid and more rigid
- creates a barrier to polar substances moving through the membrane due to hydrophobic parts |
| Role of protein channel | - allows small, charged particles through |
| Role of carrier proteins | -transports larger molecules and charged particles across the membrane by active transport and facilitated diffusion |
| Role of proteins | - acts as receptors for molecules (hormones) in cell signaling
- when a molecule binds to a protein, a chemical reaction is triggered inside the cell |
| Role of glyco-lipids and glycoproteins | -stabilizes the membrane by forming hydrogen bonds with the surrounding water molecules
- also acts as a receptor for messenger molecules in cell signaling
- are sites where drugs, hormones, and antibodies bind |
| Role of phospholipid bilayer | - forms barrier to water-soluble substances
- fat-soluble substances dissolve and pass through the bilayer |
| Why is the structure of membranes referred to as the fluid mosaic model? | fluid - phospholipids are constantly moving
mosaic - protein molecules are scattered through the bilayer |
| What are the two types or proteins found on the cell surface membrane | Intrinsic and Extrinsic |
| Define intrinsic | proteins that are firmly embedded within the phospholipid bilayer. |
| Define extrinsic | proteins are entirely outside of the membrane, but are bound to it by weak molecular attractions |
