Biology Lecture exam 3

Osmosis

The diffusion of water molecules across a selective barrier from high concentration to low concentration

Selective barrier

A barrier that allows water molecules to pass through, but not most of the molecules dissolved in water

Solutes

Molecules that are dissolved in water

The concentration of water is determined by…

The concentration of solutes in water

Solute potential

A measure of how much solutes have lowered water’s tendency to move

Pure water solute potential

=0, the highest solute potential value

What happens to the solute potential after adding solute

Negative value, lowers water concentration

Isotonic

When solute potential inside and outside of the cell are equal

Hypotonic

Solute potental is higher outside of the cell than inside, water will diffuse into the cell

Hypertonic

The solute potential is higher inside of a cell than outside, water will diffuse out of the cell

Energy

The capacity to do work

Kinetic energy

Energy of movement

Potential energy

stored energy

First law of thermodynamics

Energy cannot be destroyed or created

Second law of thermodynamics

No energy transfer is 100% efficent, Entropy continously increasing, Free energy continiously decreasing

Entropy

A measure of unsuable energy

Enthalpy

Total amount of energy contained in a molecule

Free energy formula

G=H-TS

Exergoonic reactions

change in free energy is negative, can occur spontaneously

Endergonic reactions

Change in free energy is positive, requires energy input

Reaction coupling in cells

The Free energy released by exergonic rxns is used to drive energonic rxns forward

ATP hydrolysis and reaction coupling

exergonic rxn which drives many of the endergonic rxns in the cell forward