exam 1 review Flashcards
(24 cards)
ficks equation
flux= A x D x (c2-c1) / distance
We can hence re-write the equation as the one above
* The rate (speed) of diffusion is called the FLUX
* A is the sectional area through which diffusion occurs
* (C2 - C1) is the concentration gradient across a distance
* D is the diffusion constant
* This is referred to as Fick’s equation for diffusion
distance is the enemy of difusion
osmosis
-water will go where particles are higher,
-movement of water across semi-permeable water from low to high concentration
What is tonicity?
The ability of a solution to cause a cell to gain or lose water.
isotonic- a solution w the same total concentration (non penetrating)
hypertonic- solution w higher concentration of non penetrating solutes
hypotoinc- a solution w lower concnetration of non penetrating solutes
What is osmolarity?
Total concentration of all solute particles in a solution.
Difference between osmolarity and tonicity?
Osmolarity is total solute concentration; tonicity is the effect of that solution on cell volume.
Homeostatic blood osmolarity?
~300 mOsm/L.
Two forms of passive transport?
Simple diffusion (high to low) and facilitated diffusion. (needs protein to help get thru membrane)
passive transport
no energy required, down the gradient
Difference between simple and facilitated diffusion?
Simple: molecules pass directly; Facilitated: needs channel or carrier proteins.
What drives passive transport?
Concentration gradients.
Channel vs Carrier?
Channel: small and specific
Carrier: requires binding and releasing
Types of channels?
leakage- always open
gated- closes and opens channels (chemically/voltage/ and mechanically)
Uniporters vs Coupled transporters?
Uniporters: one molecule one direction;
symporter: moves 2 substances in the same direction at the same time
anitporter: 2 substances moved but in opposite direction
active transport
low to high, needs energy and protein, needs a pump
Types of active transport?
Primary - uses PUMP
secondary active transport- uses stored energy, ALWAYS coupled w sodium Na
Example of primary active transport?
Na+/K+ ATPase.
Example of secondary active transport?
Na+/glucose symporter.
Why are they called ‘pumps’?
They use energy to move substances against gradient.
Important pumps?
Na+/K+ pump, Ca2+ pump, H+/K+ pump.
Steps from DNA to protein?
Transcription → RNA processing → Translation.
What is a promoter?
DNA sequence where RNA polymerase binds.
What is a transcription factor?
Protein that regulates transcription initiation.
mRNA vs DNA sequence?
mRNA is complementary to DNA template strand (U instead of T).
