Cell Membranes Flashcards
What two types of proteins are on the surface of a cell membrane of the fluid mosaic model?
Integral and peripheral.
Describe the bilayer structure of the fluid mosaic model.
The hydrophilic part is on outer surfaces whereas the hydrophobic part is in the inside.
What two carbohydrates exist on the surface of a cell membrane in the fluid mosaic model?
Glycoproteins and glycolipids.
Define hypertonic.
Where there is a higher concentration of solute outside of the cell, so water moves out of the cell.
Define hypotonic.
Where there is a higher concentration of solute inside of the cell, so water moves into the cell.
Define isotonic.
Where the amount of solute is balanced inside and outside of the cell.
State six functions of the plasma membrane.
- A boundary that protects the cells.
- A permeability barrier allowing internal homeostasis.
- Signal transduction.
- Cell recognition.
- Conduction of electrical signals (depolarisation).
- Cell adhesion.
Define signal transduction.
Signalling molecules from the external environment to bind to receptors and cause internal changes.
State four reasons why compartmentalisation is regarded as an advance over prokaryotic cell architecture.
- Metabolic processes are kept separate.
- Genetic material is additionally protected.
- Substrates may be concentrated in a compartment improving efficiency of enzyme action.
- Ions may be stored/released in a controlled way.
State four reasons to support the fluid mosaic model of the membrane.
- The properties of phospholipids.
- The app arrange of stained membranes under TEM at maximum magnification.
- Freeze-fracture images.
- Membrane protein mobility.
Define amphipathic structure.
Having ionic and non-ionic regions.
How is membrane fluidity controlled in animals?
By cholesterol content.
What is the purpose of cholesterol within a cell membrane?
It helps to immobilise the outer surface of the membrane and makes it less soluble to very small water-soluble molecules. It makes the membrane more firm and separate the phospholipids so that the fatty acid chains can’t come together and crystallise.
Define extracellular matrix.
A network of fibrous proteins and polysaccharides. It fills the space between cells and is secreted locally.
