1630702
Description
Flashcards by Alex Snellgrove, updated more than 1 year ago
|
Created by Alex Snellgrove
over 9 years ago
|
|
| Question | Answer |
| Structure of phospholipids | Consist of a polar head (hydrophillic) made of glycerol and phosphate, and two non-polar fatty acid tails (hydrophobic) |
| Phospholipid arrangement in membrane | Phospholipids spontaneously arrange in a bilayer, the hydrophobic tail regions face inwards and are shielded from the surrounding polar fluid |
| Structural properties of the phospholipid bilayer | Phospholipids are held together in a bilayer by hydrophobic interactions, hydrophilic and hydrophobic layers restrict entry and exit of substances, and phospholipids allow for membrane fluidity and flexibility (important for functionality) |
| Functions of membrane proteins | Transport, Receptors, Anchorage, Cell Recognition, Intercellular Joinings, Enzymatic Activity |
| Diffusion | The movement of particles from a region of high concentration to a region of low concentration (along a gradient) |
| Osmosis | The movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration |
| Passive Transport | The plasma membrane is semi-permeable and selective in what can cross, substances that move along the concentration gradient (high to low) undergo passive transport and do not require the use of energy (ATP) |
| Simple Diffusion | Small, non-polar molecules that can freely diffuse across the membrane |
| Facilitated Diffusion | Large, polar substances that cannot freely diffuse and require the assistance of transport proteins (carrier proteins and channel proteins) to facilitate their movement |
| Role of proteins pumps and ATP in active transport | Active transport is the movement of materials against a concentration gradient (from low to high) This process requires the use of protein pumps which use the energy from ATP to translocate the molecules against the gradient The hydrolysis of ATP causes a change in the protein pump resulting in the forced movement of the substance, protein pumps are specific for a given molecule, allowing for movement to be regulated (e.g. to maintain chemical gradients) |
| Describe how the fluidity of the membrane allows it to change shape, break and reform | The membrane is held together by the weak hydrophobic associations between phospholipids This allows for membrane fluidity and flexibility, as the phospholipids can move about to some extent This allows for the breaking and remaking of membranes, allowing larger substances access into and out of the cell (active process) |
| Endocytosis | The process by which large substances (or amounts of smaller substances) enter the cell without travelling across the plasma membrane The invagination of the membrane forms a flask-like depression which envelopes the material, the invagination is then sealed off forming a vesicle |
| Invagination | The infolding of a sheet of cells |
| Phagocytosis | The process by which solid substances (e.g. food particles) are ingested (usually to be transported to the lysosome for break down) |
| Pinocytosis | The process by which liquids and solutions (e.g. dissolved substances) are ingested by the cell (allows quick entry for large amounts of substance) |
| Exocytosis | The process by which large substances exit the cell without travelling across the plasma membrane Vesicles (usually derived from the golgi) fuse with the plasma membrane expelling their contents into the extracellular environment |
Want to create your own Flashcards for free with GoConqr? Learn more.