biology chapter 8

BIOLOGY CHAPTER 8Osmosis and Cells

Osmosis- the diffusion of water

the movement of water from an area where there is more water to an area where there is less water

controlled by the amount of solute in a solution

solutions: solute- substance dissolved by

something else solvent- substance that does the

dissolving

cells are usually in a watery environment

remember, cells can’t stop movement of water

3 TYPES OF SOLN CELLS CAN BE IN:

1. isotonic soln-iso- means equal

a soln in which the concentration of particles OUTSIDE the cell is the same as the conc of particles INSIDE the cell

water moves INTO & OUT of cell in the same amount

2. HYPOTONIC SOLN: hypo- means LOWER a soln in which the conc of dissolved

particles OUTSIDE cell is LOWER than the same dissolved particles inside the cell

water moves INTO THE CELL until conc equals out

cell swells as water moves in animal cells may burst or LYSE if too

much water gets in

plant cell swells; cell membrane PUSHES against cell wall

TURGOR PRESSURE is maintained plant erect

3. HYPERTONIC SOLN hyper- means HIGHER soln in which the conc of dissolved

particles OUTSIDE cell is HIGHER than the conc of same particles inside the cell

water moves OUTof the cell

animal cells lose water & shrink or CRENATE

plant cells lose turgor pressure & plant wilts aka plasmolysis

WHAT SOLN IS THE CELL IN & WHICH WAY WILL WATER MOVE?

WHAT SOLN IS THE CELL IN & WHICH WAY WILL WATER MOVE?

WHAT SOLN IS THE CELL IN & WHICH WAY WILL WATER MOVE?

Cells need certain substances- food, oxygen, ions- inside them

got to go thru cell membrane

transported into cell in 2 ways

2 TYPES OF TRANSPORT:

1. passive transport- occurs as a cell uses NO energy to move particles

osmosis & diffusion are ex of

passive transportparticles are small & will move

from where there is more of them to where there is less

sometimes particles are too large to go thru cell membrane easily but still moving along conc gradient (from more to less)

have to have help- particles will move thru the transport proteins in cell membrane

this is called facilitated diffusion

2. active transport- movement of particles against conc gradient that requires cell to use energy

cell is moving particles from a LOW CONC to an area of HIGHER CONC

transport proteins have to be used

SEVERAL TYPES OF ACTIVE TRANSPORT:a. endocytosis- cell surrounds &

takes in materials from envendo- within

b. phagocytosis- another cell is moved into cell ex: white blood cell engulfs invading bacteria

c. pinocytosis- engulfing of liquid particles

d. exocytosis- expelling of waste & bits of matter

exo- means outside

REMEMBER: passive transport: no energy is

used & particles are moved from MORE TO LESS

active transport: energy is used to move particles from LESS TO MORE

WHAT TYPE OF TRANSPORT DOES THIS ILLUSTRATE?

WHAT TYPE OF TRANSPORT DOES THIS ILLUSTRATE?

WHICH REQUIRES MORE ENERGY TO DO?