Lectures 13 & 14

Question 1

osmosis

Answer 1

diffusion of water molecules across a selective (semi-permeable) barrier
* high to low concentration

Question 2

selective (semi-permeable) barrier

Answer 2

a barrier that allows water molecules to pass through, but not most of the molecules dissolved in the water
ex. plasma membranes

Question 2

How concentrated is water with no solutes?

Answer 2

100%

Question 3

The concentration of water is determined by _____.

Answer 3

concentration of solutes in the water

Question 4

solutes

Answer 4

molecules that are dissolved in water

Question 5

What happens to water concentration when you add solutes?

Answer 5

water concentration goes down

Question 6

Solute potential

Answer 6

measure of the concentration of solutes dissolved in water

Question 6

What does adding solutes do to solute potential and H2O concentration?

Answer 6

lowers Ψs < 0
Lowers H2O concentration

Question 7

What is the solute potential when a water has no solutes

Answer 7

0

Question 8

correlations between solute potential, solute concentration, and water concentration

Answer 8

• solute potential and water concentration = direct
• both inverse w/ solute concentration

Question 9

water moves from ___ solute potential to areas of ___ solute potential

Answer 9

higher, lower

Question 10

isotonic

Answer 10

Ψs inside and outside of a cell are equal
Water enters and leaves cell in equal amounts

Question 11

hypotonic

Answer 11

Water concentration is higher outside of the cell than inside
Water will diffuse into the cell → cell will swell → cell bursts

Question 12

hypertonic

Answer 12

Water concentration is higher inside the cell than inside
Water will diffuse out of the cell → cell will shrink → cell could dehydrate and die

Question 13

brain capillaries

Answer 13

fine blood vessels that feed brain tissue

Question 14

Blood-Brain-Barrier definition, problem, and solution

Answer 14

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

Question 15

kinetic energy

Answer 15

energy of motion
Ex. heat, light, mechanical (wind, water)

Question 16

potential energy

Answer 16

stored energy
Ex. concentration gradient, chemical bonds

Question 17

first law of thermodynamics

Answer 17

Conservation Law:
Energy cannot be created or destroyed, can only change from one form to another
Total amount of energy in universe reaminds constant

Question 18

Second Law of thermodynamics
(definition of entropy and free energy)

Answer 18

• 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

Question 19

free energy formula

Answer 19

G = H - TS
* H=enthalpy
*T=temp
*S=entropy

Question 20

enthalpy

Answer 20

total amount of energy (usable and unsable) contained in a molecule

Question 21

What determines the 2 types of reactions

Answer 21

change free energy

Question 22

-△G = exergonic

Answer 22

(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

Question 23

2 types of rxns

Answer 23

-△G = exergonic (products have less free energy than og reactants)
+△G = endergonic (products have more free energy than og reactants)

Question 24

+△G = endergonic

Answer 24

(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

Question 25

Reaction coupling

Answer 25

Exergonic and endergonic rxns are coupled together
Energy to drive endergonic (energy requiring) reactions comes from exergonic ( energy releasing reactions)

Question 26

ATP

Answer 26

energy currency of cell

Question 27

ATP Hydrolysis
* exergonic or endogonic
* reactants
* products

Answer 27

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