Forces Across Membranes Flashcards
What does it mean to say membranes are Dynamic?
Constantly formed, maintaines, dismantled or metabolised depending on the cells needs
What makes cell membranes flexible?
The fatty acids
What are the 2 classes of membrane protein?
Integral
Peripheral
What makes an integral membrane protein?
- Cant be removed without disrupting the membrane
- Amphipathic & oriented the same way as the phospholipids
What are the 4 types of integral membrane protein?
- Channels
- Carriers
- Enzymes
- Receptors
What are peripheral proteins important for?
Cell shape & motility
What makes up schwann cell membranes?
18% protein
Mainly lipid for insulation against electrical nerve signals
How much protein is in the average cell?
Around 50%
What factors aid diffusion?
Large surface area
High Permeability
High conc. gradient
What characteristics must a molecule have to diffuse through the lipid bilayer?
- Small
- Uncharged
- Hydrophobic (lipophilic)
What is a protein channel?
A trans-membranous IMP that act as an aqueous route for ion diffusion
Name the protein channels through which water goes?
Aquaporins
What are the two types of ‘gated’ channel?
Voltage gated
Ligand Gated
In general what is the electrical gradient across cell membranes?
USually the inside is relatively negative to the outside
How do carrier mediated transport systems work?
A solute binds to a transmembranous protein
The protein changes coniguration
Solute is now exposed to the other side of the membrane
Solute detaches into the cell