Membrane Transport Flashcards
What is permeability related to and why
If the molecule is hydrophobic the molecules can pass through the membrane
The greater the size and the more water soluble the molecule the less permeability
True or false
Ions can freely pass through the lipid bilayer
False
True or false
Large and small uncharged polar molecules are semi permeable
True
What are the two types of transport proteins
Ion channels and transporters
What are the different types of transporters
Passive transporters
Secondary active transporters
Primary active transporters
P-type, F- and v-type , ABC-type
Which is higher inside or outside of the cell
Na+
K+
Na + lower in the cell than outside
K+ higher in the cell than outside
What are the different classes of ion channels
Voltage gated
Ligand gated ( extracellular or intra cellular
Mechanically gated
How do voltage gated ions channels work
By change in voltage
How do ligand gated ion channels work
They are opened to respond of the binding of a ligand to the active site
How do mechanically gated ions channels work
The respond to stress and stretch forces upon the cell membrane
What type of molecules need transporters
Hydrophilic
What are the main features of the passive transporters and how do they work
. Small hydrophilic molecules down their concentration gradients
. No energy required
. Uniport (one direction)
. No Hole (no aquas pore)
. Binding of the cargo molecule and conformational change helps the molecules move across
How fast are passive transporters and why
Relatively slow because they are highly selective
True or false
Passive transporters are saturable
True
It means they have a maximum rate of diffusion
Give one example of a passive transporter
Glucose transporters (GLUT)
1,2,3,4,14
Slc2 class 1
What are the two types of active transporters
Primary and secondary
How do primary active transporters work
ATP hydrolysis
Pumps
What type molecules do primary active transporters transport
Ions and small hydrophilic molecules
True or false Primary active transporters can be called channels
False
How do primary active transporters work
Using ATP hydrolysis which causes a conformational change and enables them to move to to other side
True or false they can be uniporters ,symporters and anti porters
True
Are they fast or slow and why
Slow as they are selective and also saturable
What do v and f type pumps transfer
Protons (H+)
Explain p type pumps
. They move cations
. The pump becomes phosphorylated when ATP is hydrolysed, this results in conformational change allowing ions to move from one side to another
What is one primary example of p type pumps
Sodium and potassium -ATPase
Most abundant
And calcium-ATPase
In plasma membrane and in sarcoplasmic and endoplasmic reticular (serca)
Where are v and f type pumps found
Organelles for v
Inside of organelle is more acidic by pumping h+
Inner mitochondrial membrane for F
For ATP synthesis.
How do ABC transporters work
Using ATP binding and hydrolysis however this does not use phosphorylation.
What is one important example of molecules transported via abc transporters
P-glyco protein
Pumps hydrophilic drugs non selective through cell membranes.
How do secondary active transporters work (coupled transporters)
Both solutes must be present which means they can be symport and anti port the energy comes from the dissipation of the potential energy in the ion. One moves down it’s gradient in order for another molecule to move up its gradient.
