Principles of Biology Chapter 5 ULM

crenation

cells in a hypertonic medium lose water and shrink

osmotic lysis

cells in a hypotonic medium gain water can pop

plasmolysis

cells in a hypertonic medium lose water and the plasma membrane pulls away from the cell wall

osmosis

when water diffuses to the side with lower water concentration

contractile vacuoles

take up water and discharge it outside the cell

to maintain a constant cell volume

vacuoles are used to remove excess water

freshwater protist like Paramecium have to survive in a

strongly hypotonic environment

transport proteins

transmembrane proteins that provide a passageway for the movement of ions and hydrophilic molecules across membranes

two classes of movement

channels and transporters

channels

allow the direct diffusion of ions or molecules across the membrane

most channels are

gated

Example of a channel

Aquaporins

conformational change

transports solute across membrane

conformation change is the principal pathway for

organic molecules (sugars, amino acids, and nucleotides)

uniporter

a single molecule or ion is bound and transporter

Symporter

Two or more ions or molecules are transported in the same direction

antiporter

two or more ions or molecules are transported in opposite directions

primary active transport uses

a pump, uses energy to transport solute

Secondary active transport

uses a different gradient to drive movement, uses a preexisting gradient to drive transport

antiporter

ions move in opposite directions

electrogenic pump

exports one net positive charge

gap junctions

connect animal cells

plasamodesmata

connect plant cells

adjacent cells

intercellular channels allow the direct movement of substances between