Term
| Outline how different molecules can go thought the membrane |
|
Definition
1) Small (or even big) and hydrophobic (i.e. O2, CO2, N2, steroids and hormones) - no problem
2) Small uncharged (i.e. H2O, urea, glycerol) the transport is reasonably working due to osmos
3) Large uncharged or polar or ions - only by channels. |
|
|
Term
| Ouline main types of diffusion thought membrane |
|
Definition
1. Simple diffusion(passive, difference in the electro – chemical gradient is trigger)
2. Facilitated diffusion(passive type,thought channels by gradient)
3. Primary active (against gradient, require ATP)
4. Secondary active(against gradient,can be synport and antiport)
5. Ions channels |
|
|
Term
| What kind of transport can transporters maintain? |
|
Definition
|
|
Term
| How transporters work? How the selectivity of transporters is maintained? |
|
Definition
Transporters usually undergo substantial conformational changes.
Their selectivity is based on the form of the binding pocket, they also can change their affinity |
|
|
Term
| What kind of transport can channels maintain? |
|
Definition
|
|
Term
| How the selectivity of channels is maintained? |
|
Definition
They are mainly ion channels
Selection is achieved by opening and closing,size and charge, only very little conformational changes |
|
|
Term
| Outline the main features of ion channels |
|
Definition
1) form a temporary ‘opening’ in the membrane
2) only limited flexibility
3) minor conformational changes of the protein
4) bidirectional
5) flow always with the concentration gradient
5) very high flow rates
6) good selectivity
|
|
|
Term
| What is the main types of gating? |
|
Definition
1. Voltage gating channels
2. Ligand activated, i.e. Ca2+ channels in ER
3. Mechanic-sensitive |
|
|
Term
| What is the structure of aquaporin? |
|
Definition
Aqua porin consists from four subunits. Each subunit can transport water, however, they can work only in complex: subunits are used to form a pore.
In the pore aquaporin has two half helices, in the place, there they meet there is a ANP triplet. Water goes though the channel one by one, also there is no environment for ions to substitute their water halo. |
|
|
Term
| What decases are caused by aquaporin misfunction? |
|
Definition
1. abnormal function of the kidney
2. loss of vision
3. hearing loss or impairment cerebral oedema |
|
|
Term
| What mechanism prevents H+ from going thougth water channel? |
|
Definition
|
|
Term
| How Grotthus mechanism works? |
|
Definition
|
|
Term
| What are the main features of transporters? |
|
Definition
1) form a complexes with substrates(specificity)
2)do not form temporal opening in the membrane.
3) transporting against gradient
4) changes from very high affinity to low → major conformational changes
5) non directiona
Regulation is by inhibition allosteric inhibition or ligand or electrochemical gradient.
|
|
|
Term
| What LacY is for? How it is working? |
|
Definition
It is secondary active galactoside:proton symporter
Transport of H+ with its concentration gradient drives the symport of lactose |
|
|
Term
| How Na+/Ka+ ATPase works? What is it required for? |
|
Definition
It catalyses exchange of two potassium for three sodium transport of both against their concentration gradient ,
maintains the membrane potential of the plasma membrane
transport is governed by phosphorylation/dephosphorylation |
|
|
