unit 2; ap bio

vocab

Salinity

The measure of salt concentration in water or soil.

Permeability

Describes the ability of something (usually the cell membrane) to allow substances to pass through it or not. If the membrane is permeable to that substance, it goes through.

water soluble

can be dissolved in water

fat soluble

can be dissolved in fats + oils. not in water

osmolarity

the concentration of a solution expressed in number of solute particles per liter

molarity

molarity is a concentration and higher molarity means a higher concentration

active transport

The use of energy to pump molecules from low to high concentration

Secondary active transport/cotransport

Using the energy of a concentration gradient to move a substance. Recall that ATP was used to establish the gradient first (usually its an ion gradient). Then a channel opens for the facilitated diffusion of the ion and this flow can  pull another substance up its gradient. 

contractile vacuoles

Vacuoles in some species of plant and protist cells that pump out excess water when turgor pressure gets too high

water potential

The measure of the tendency of the water in a solution to move from one area to another, compared to pure distilled water. Represented by the Greek letter ψ (Psi).

solute potential

pressure which needs to be applied to a solution to. prevent the inward flow of water across a semipermeable membrane

lumen (internal space)

The internal space of some structure

electrochemical gradient

A difference in charge between the outside and inside of the cell due to uneven concentrations of ions in those two areas

concentration gradient

When a molecule is at a high concentration in one area and a low concentration in another. Usually we're referring to two areas separated by a cell membrane

aqueous

water based

aquaporin

transport channels in many types that allow for the diffusion of water into and out of cells

tonicity

This refers to hyper-, hypo-, and isotonic. It is a measure of the potential of one solution in relation to another

isotonic

When a solution has the same solute concentration as the cell, no net diffusion occurs

hypotonic

When the solution a cell is in has a lower concentration of solute than the cell. Cell gains water.

hypertonic

When the solution a cell is in has a higher concentration of solute than the cell. Cell loses water.

hydrolysis

Breaking down a polymer into monomers by adding OH and H (water)

glycoprotien

Membrane proteins with carbohydrate chains attached that act as cell recognition markers and help attach cells to form tissues

turgor pressure

Turgor pressure pushes the plasma membrane against the cell wall of plant, bacteria, and fungi cells.

facilitated diffusion

When diffusion occurs through a transport channel or other transmembrane protein

simple diffusion

The movement of molecules from high to low concentration

what can go right through the lipid bilayer?

non-polar molecules (hydrophobic), gases (N2, O2, CO2), small lipids

what needs a channel to go through the lipid bilayer?

polar or charged molecules (hydrophilic)

glucose

monosaccaride (can fit through small pores)

starch

polysaccharide (can not go directly through a membrane)