Facilitated Diffusion & Active Transport Flashcards
What are uniports?
Transport of one substance across a membrane
What are symports?
Transport of two or more substances one direction
What are antiport?
Transport of two or more substances in opposite directions
What is facilitated diffusion?
diffusion of large, membrane insoluble compounds such as sugars, amino acids, and ions across a biological membrane utilizing transport proteins (aka carrier proteins)
Does not require energy (passive)!!!!
follows all the rules for diffusion (substances flow from high
concentration to low concentration , etc.)
What is highly selective facilitated diffusion?
Substance binds to membrane-spanning transport protein
– Binding alters protein conformation, exposing the other surface
What is fully reversible facilitated diffusion?
Molecules may enter the cell and leave the cell through the transport protein.
What is GLUT-1?
a facilitated diffusion carrier protein
allowing glucose to enter cell
What are ion channels?
Essentially, these are facilitated diffusion
carrier proteins for ions
Ions flow down both concentration and
electrochemical gradients
-Pores which selectively allow ions to enter cell
What is the activation transport?
Movement across membrane with an energy cost (usually against concentration or electrochemical gradient, but not always)
-Used to pump specific compounds in or out of the cell
-Requires energy to overcome the concentration and electrochemical gradient or to allow a large or charged particle to cross membrane
-Requires specific integral membrane proteins
– Can be saturated like facilitated diffusion proteins
– The energy comes from facilitated diffusion
What is the K+ / Na+ Pump?
Most Important: Activates by phosolipid head connecting to the pump. Then 3 sodium’s enter and bind to where they are supposed to be. After this the potassium is lead to the pump and then plugs itself into pump. The door on the other side of the membrane opens up to let the sodium into blood stream. After the potassium goes back to small intestines. Then process keeps repeating
-K+ and Na+ transport require ATP energy
- this pump will only work if [K+] is high on
outside and [Na+] is high on inside.
– This pump works independent of concentration gradient
Why is the Co transport important?
(Secondary Active Transport)
A active transport is used to create a
gradient
This gradient is then used to transport other
molecules across a membrane via
facilitated diffusion
involves two or more transport proteins
What does Co-transport look like in plants?
Plants usually use H+ gradients to power
co-transport
What does Co-transport look like in Animals?
Animals usually use Na+ gradients to
power co-transport
How does the H+ / Sucrose Co-transport System work?
H+ pump actively transports H+ across the
membrane, creating a great H+ gradient.
These gradient drives transport of H+ and
sucrose into the cell via facilitated diffusion
– H+ concentration is greatest outside the cell
- Sucrose concentration is greatest inside the cell
NET gradient is greater outside the cell,
and this is what powers transport of both H+
and sucrose into the cell
