Chapter 6 Part from uni 2 Flashcards
What are the two primary factors that will affect how solutes move across a membrane?
- Is the membrane permeable to the solute
- is the solute moving in a thermodynamicly favored direction.
What effects thermodynamics of movement across membranes?
Entropy,
- if the two sides of the membrane have equally ordered sides than it has a high entropy.
- if the two sides of the membrane have a concentration difference between sides of the membrane than it has a low entropy.
What are the two thermodynamically-driven processes that work to equalize the concentration differences?
- Diffusion
- Osmosis
What is Diffusion?
Membrane is permeable to the solute.
Thus, the solute is favored to cross the membrane and move from a high to low concentration, therefor toward a maximus entropy state.
What is Osmosis?
- Occurs when the membrane is impermeable to the solute.
- Therefor, water moves from the low solute side to the high solute side.
What direction does water move in a osmotic permeable based membrane?
hypotonic to the hypertonic side
What consequences can osmosis have on a cell?
cell shrinkage or cell bursting.
- depends whether the inside or the outside of the cell is hypo/hyper tonic
Isotonic?
Same concentration of dissolved particles.
If the solute is charged, then we also have to consider more than just the concentration gradient of that cell. Why?
undermost conditions cells contain a net charge difference across their cell membrane.
- Inside of the cell has a negative net charge
- outside of the cell has a positive net charge
- Therefore, there is already an electrochemical gradient.
What are things you need to considered when thinking about a solute moving across a membrane?
- Is the solute a charged particle.
- Is that ion moving against or with the electrochemical gradient
What is DELTA:G(sub c)?
change is free energy associated with movement of the solute relative to it’s concentration gradient
What is DELTA:G(sub m)?
Change in free energy associated with the movement of a charged solute relative to the electrical gradient across the membrane.
- If the membrane permeable to the solute
-if the solute moving in a thermodynamic favored direction.
IF THE ASWER IS YES TO BOTH QUESTIONS, WHAT IS OCCURING?
Simple diffusion
-if the solute moving in a thermodynamic favored direction. (only this)
IF THE ASWER IS YES TO just this QUESTION, WHAT IS OCCURING?
facilitated diffusion
- If the membrane permeable to the solute
-if the solute moving in a thermodynamic favored direction.
IF THE ASWER IS NO TO BOTH QUESTIONS, WHAT IS OCCURING?
active transport
What is the function of channel proteins?
Create an open channel through the membrane that allows for the movement of ions.
- Key for facilitated diffusion
t/f most channel proteins are highly accepting of all ions?
false, most are highly selective.
t/f most channel proteins are gated?
True, they can open and close depending upon what is the circumstances are. ex voltage gated channel proteins
What is function of carrier proteins?
- involved in facilitated diffusion
- ## ex: Glut 1. moves glucose from high-low concentrations
What determines the directionality of movement in carrier proteins?
Thermodynamics, the carrier protein just serves as a functioning pathway.
What is active transport?
energy is required to move the charged particles in un-energetically favored direction.
- Requires membrane proteins
What is the difference between primary and secondary active transport?
Primary: (direct active transport), energy comes from the hydrolysis of ATP
Secondary: (indirect active transport), energy comes from coupling an energetically unfavorable transport process to an energetically favorable transport process.
What is the best-studied example of active transport:
(Na+/K+/ATPase) pump
What is the function of a symporter?
movement of two molecules in the same direction.
