Flashcards in Water and Movement Across the Membrane Deck (32):
What does amphipathic mean?
- A molecule containing an area of hydrophobic and of hydrophilic nature
How do water soluble molecules arrange themselves in solution?
- Water- water H bonding of the water is replaced by
- Water- solute bonding
What do water soluble molecules arrange themselves like this?
- Water-solute hydrogen bonding is more favourable
How do uncharged molecules arrange themselves in water?
In such a way that will bring the least amount of disruption to the water-water bonds
What are uncharged molecules said to form in solution?
What do phospholipids form to minimise water disruption?
What are buffers?
Solutions of weak acids that dissociate to form a conjugate acid-base
What 3 things aid diffusion?
- Large surface area
- High permeability
- High conc. gradient
What 3 properties do molecules need to have to diffuse across the membrane?
What 2 elements can cross the membrane easily?
Because they are small and uncharged (symmetry)
What two waste compounds can easily cross the membrane?
What are the 2 classes of membrane proteins?
4 types of integral proteins?
What happens to the plasma membrane if integral proteins are removed?
It is disrupted
Relative "amphipathicness" of integral and peripheral proteins
Integral = amphipathic
Peripheral = not
Where are peripheral proteins found?
Inner side of the membrane
What do peripheral proteins tend to be?
What do peripheral proteins play a key role in?
Cell shape and motility
What is an example of a peripheral protein that is important for cell shape and motility (hint: the gene for its coding is lost in duchennes dystrophy)
Name two cells and their membrane protein percentage to show how different membranes can be
- Schwann cells (18%)
- Mitochondria (75%)
What protein does water use to enter/exit the cell?
What are the 2 types of gated channels
- Voltage gated
- Ligand gated
How does voltage changes cause voltage gated channels to open??
- It acts on charged regions of the protein
- Causes a conformational change
- Number of osmoles of solute per litre of solution
- Number of osmoles of solute per kg of solvent
Osmolarity of 1M of glucose?
Osmolarity of 1M of NaCl
What determines the tonicity?
Conc of non penetrating solutes on 2 sides of the membrane
What happens if the ECF has a higher tonicity than the ICF?
- Cell is hypotonic
- Cell will swell as water enter
What happens if the ECF has a lower tonicity than the ICF?
- Cell is hypertonic
- Cell will shrink as water leaves
What is an isosmotic solution?
Equal number of both penetration and non penetrating solutes on either side of the membrane