Lectures 13 & 14 Flashcards
osmosis
diffusion of water molecules across a selective (semi-permeable) barrier
* high to low concentration
selective (semi-permeable) barrier
a barrier that allows water molecules to pass through, but not most of the molecules dissolved in the water
ex. plasma membranes
How concentrated is water with no solutes?
100%
The concentration of water is determined by _____.
concentration of solutes in the water
solutes
molecules that are dissolved in water
What happens to water concentration when you add solutes?
water concentration goes down
Solute potential
measure of the concentration of solutes dissolved in water
What does adding solutes do to solute potential and H2O concentration?
lowers Ψs < 0
Lowers H2O concentration
What is the solute potential when a water has no solutes
0
correlations between solute potential, solute concentration, and water concentration
- solute potential and water concentration = direct
- both inverse w/ solute concentration
water moves from ___ solute potential to areas of ___ solute potential
higher, lower
isotonic
Ψs inside and outside of a cell are equal
Water enters and leaves cell in equal amounts
hypotonic
Water concentration is higher outside of the cell than inside
Water will diffuse into the cell → cell will swell → cell bursts
hypertonic
Water concentration is higher inside the cell than inside
Water will diffuse out of the cell → cell will shrink → cell could dehydrate and die
brain capillaries
fine blood vessels that feed brain tissue
Blood-Brain-Barrier definition, problem, and solution
strict control of what can go out of the bloodstream into blood tissue (so toxins and bad things don’t go into brain tissue)
* Problem - when doctors need to introduce medicines into the brain b/c blood brain barrier keeps most medicines from entering the brain (no receptors and transporters to get them in)
* Solution - doctors inject a solute into the blood: now H2O concentration is higher inside the CWS than in the blood → water diffuses out of CWC into blood
- CWC shrink and create space between the cells so medicine can go through
kinetic energy
energy of motion
Ex. heat, light, mechanical (wind, water)
potential energy
stored energy
Ex. concentration gradient, chemical bonds
first law of thermodynamics
Conservation Law:
Energy cannot be created or destroyed, can only change from one form to another
Total amount of energy in universe reaminds constant
Second Law of thermodynamics
(definition of entropy and free energy)
- No energy transfer is 100% efficient
- Some energy is always lost (usually heat) and becomes unusable
- Entropy (unusable energy) in universe is continuously increasing
- Free energy (usable energy) in the universe is continuously decreasing
free energy formula
G = H - TS
* H=enthalpy
*T=temp
*S=entropy
enthalpy
total amount of energy (usable and unsable) contained in a molecule
What determines the 2 types of reactions
change free energy
-△G = exergonic
(products have less free energy than og reactants)
Free energy is released and can be used to do work
Could occur spontaneously: rxn has the potential to go forward without extra energy
Brick analogy: over time, a nice stack of bricks will fall over and decay
2 types of rxns
-△G = exergonic (products have less free energy than og reactants)
+△G = endergonic (products have more free energy than og reactants)
+△G = endergonic
(products have more free energy than og reactants)
Energy is absorbed (input of energy required)
Never occur spontaneously: rxn won’t go forward without input of energy
Brick analogy: over time, a nice stack of bricks won’t have more bricks added upon itself
Reaction coupling
Exergonic and endergonic rxns are coupled together
Energy to drive endergonic (energy requiring) reactions comes from exergonic ( energy releasing reactions)
ATP
energy currency of cell
ATP Hydrolysis
* exergonic or endogonic
* reactants
* products
exergonic rxn
Reactants: high free energy ATP and H2O
Products: lower free energy ADP + other products
-△G (energy is released): energy is used to power endergonic rxns in a cell
