Chapter 10 Flashcards
Transport proteins are important for transmembrane movement of these ions and metabolites.
Na+, K+, Ca2+, and Cl- ; amino acids, sugars, nucleotides and water
Diffusion of a Substance
A (out) A(in)
If [A]out is greater than [A]in, delta (GA) will be ______. The net flow will be ________.
negative ; inward (spontaneous)
If [A]in is greater than [A]out, delta (GA) will be _______. The net flow will be ________.
positive ; outside
_____ differences change as ions (charged) go through the membrane.
Chemical potential
1 V =
J/c
If a reaction has a positive delta G (+), it needs to __________.
be coupled with a reaction to make it (-)
Simple Diffusion
Small molecules just pass right pass through the membrane
Passive Mediated Transport
Spontaneously flow from high to low concentration (no energy needed.
Active Mediated Transport
Endergonic reaction ; flow from low to high concentration. Requires energy. It has to be coupled to an exergonic process.
Carrier Ionophore process
1) comes to one side of the membrane
2) grabs ion
3) Goes through the other side of the membrane
4) Releases it
5) Repeats
Valinomycin
A type of ionophore.
- Rolls up around K+ ions and methyl groups are on the outside
- Makes it an octahedral complex
- Becomes hydrophobic
K+ channel
- Na+ ions can’t go through K+ channel
- The channel is super selective
- K+ has water molecules around it
- There is a selectivity filter.
- Complex scaffolding of water molecules
- As it goes through the filter, K+ replaces water for oxygens on proteins
Why can’t Na+ go through the K+ channel?
It is not geometrically optimized to go through the channel. Too much energy would be needed.
Substances too large or too polar are carried across the membrane through
- Carriers
- Permeases
- Channels
- Transporters
Ionophores
Organic molecules (usually of bacterial origin) that increase the permeability of membranes to ions.
Uniport
Translocation system where one molecule is moving at a time
Symport
Translocation system where 2 different molecules are being transported at the same time as long as the channel is optimized for each molecule type.
Antiport
Simultaneously transports two different molecules in opposite directions
Aquaporin
- There are two asparagine residues inside the aquaporin channel. Apsaragine has a positive and negative end.
- Water is attracted into the aqua by the porin’s negative ends of the asparagines.
Glucose Transport
1) Glucose molecule binds to the protein
2) The protein (specific to glucose) folds up around it
3) Goes through the membrane and releases the glucose (dissociates glucose)
4) System resets
Na+-K+ ATPase is a type of ___________.
Active Transport, requires energy to push ions out of the gradient.
Which is energy dependent?
Active Transport
Which is energy independent?
Facilitated Transport, Simple Diffusion
Which needs some kind of carrier protein(s)?
Facilitated Diffusion, Active Transport
Which doesn’t need some kind of carrier protein?
Simple Diffusion
Which can be saturated by substrate?
Facilitated Diffusion, Active Transport
Which can establish a concentration gradient?
Facilitative Diffusion, Active Transport
