Membrane Transport Flashcards
What does the fact that membranes are largely impermeable allow the cell to do
Why is the membrane largely impermeable
Which molecules are able to go through the membrane
What are the type main classes of membrane transport proteins
Transporters and channels
What do channels do
What does transporters do
Efflux= removal of waste products and toxins
Transport of amino acids, sugars and co factors into cell
What is meant by transport proteins are substrate specific
How do transporters work
How do channels work
What is facilitated diffusion
Is a type of passive transport
What is the electrochemical gradient
How does polarity of the membrane influence transport of ions across the membrane
What is active transport and how does it work
What are the 3 sources of energy for active transport
What are the 3 types of transporter mediated movement
How do coupled transporters work
How do the two types of active transport occur
Primary active transport directly uses chemical energy (usually ATP) to move molecules across a membrane. The energy derived from ATP hydrolysis is used to change the conformation of the transport protein, which allows the molecules to be transported across the membrane.
Secondary active transport, also known as cotransport, does not use ATP directly. Instead, it relies on the electrochemical gradient established by primary active transport. The energy stored in these gradients is used to move other substances against their own concentration gradients
How does lactose permease work
What are the characteristics of channels
What are the four types of gated channels
How are channels selective in what goes through
What are the roles of ion channels
What type of channel is a K+ channel
Exporting channel
Exports potassium ions inside the cell to outside
Label the different parts of this K+ ion channel
What is the role of the selectivity loop of the K+ channel
It acts as a selectivity filter
What parts of the K+ channel encourage K+ to go through the pore
Pore helix because it is dipolar (so K+ is attracted to negative end which is closest to the pore)
Selectivity filter
Pore width is perfectly sized to fit a sodium ion
Negatively charged near the entrance of the pore and towards the exits of the pore
What increases the speed of potassium ion transport through a potassium ion channel
Why are only two of the carbonyl binding sites in the selectivity filter used at one time
How does a voltage gated potassium ion channel stay closed when the inside of the cell is negative and the outside is positive
What is the role of the S4 helix
How do voltage gated potassium ion channels open
(Ignore the if no ones can pass through)
What is the role of the S1-S3 helices
What are the characteristics of aquaporins
How does an aquaporin work and prevent the passing through of other ions
(Role of asparagine and arginine residues)
(Why are there funnel like structures at each end of the aquaporin)
What drugs have been developed to target ion channels
What are some examples of channelopathies
Why aren’t Na+ transported through K+ channels
