The Cell in ActionExchange with the Environment

What would happen if a factory’s power was shut off?

Or their supplies never arrived? Or they couldn’t get rid of its garbage?

Cells are like factories Both need to obtain energy and get

things in (nutrients) and out (wastes) These things keep the cell healthy and

able to divide Cells dividing is what allows organisms to

grow

What part of the cell controls the things in and out of the cell?? CELL MEMBRANE!

What is Diffusion? Diffusion- the movement of particles

from regions of higher density to regions of lower density

Let’s visualize it

Diffusion of water The diffusion of water is called osmosis

Osmosis- the diffusion of water through a semipermeable membrane

Semipermeable?? Semi – partially Permeable- accessible/permeable/passable

It means only certain substances can pass through

Let’s see it in a

ction!!

The Cell and Osmosis Cells need a certain amount of

water in them Not too much and not too little!

If red blood cells could burst if they had too much water

Plants wilt if they don’t have enough water in their cells

Moving Small Particles Small particles (like sugars) cross the

cell membrane through passageways called channels The channels are made of proteins They pass through the channels by either

active or passive transport

Passive Transport Passive transport- the movement of

substances across a cell membrane without the use of energy by the cell Examples: diffusion and osmosis

Let’s see it!

Active transport Active transport- the

movement of substances across the cell membrane that requires the cell to use energy Usually is particles moving from

an area of low concentration or an area of high concentration Or…low density to high density

Let’s see it!

Moving Large Particles Small particles cross the cell membrane by

Diffusion Active transport Passive transport

Large particles use the processes called endocytosis and exocytosis

Endocytosis Endocytosis- the process by which a cell

membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell Vesicle- sacs formed from pieces of cell

membrane

cellPROTEIN

Exocytosis Exocytosis- the process in which a cell

releases a particle by enclosing the particle in a vesicle that then moves to the cell surface and fuses with the cell membrane Things like wastes..EXIT (EXO) the cell

Endocytosis and Exocytosis

Let’s see it in action!!

Review Describe diffusion How is osmosis different than diffusion? Why is osmosis important for cells? Describe passive transport

Is it high to low concentration or low to high? Does it require energy?

Describe active transport Is it high to low concentration or low to high? Does it require energy?

Describe endocytosis Describe exocytosis

Review How would the following materials get

through a cell membrane and into a cell Pure water Sugar entering a cell with a high

concentration of particles Sugar entering a cell with a low

concentration of particles A protein

How would wastes get out of a cell?