Download Created by Tiarra Moore Crawford Long Middle School Atlanta, GA

The Cell and Its Environment
Cell
Membrane
Selectively
Permeable
water bubbles.wav
Osmosis
Passive
Transport
Active
Transport
Diffusion
Created by Tiarra Moore
Crawford Long Middle School
Atlanta, GA
Cells have structures that
protect their contents
from the outside.
All cells are surrounded by a cell
membrane that separates the cell
from the outside environment.
Cell
Membrane
Protects the
contents of cells
The cell
membrane
is
selectively
permeable,
which
means that
some
substances
can pass
through
while
others
cannot.
Cells must let things enter
and leave.
IN
Oxygen, water, and
food molecules
OUT
Waste products
Does a cell really need a
semipermeable membrane?
What if it didn't have one?
Oooh.wav
creaky door2.wav
How can substances move into and out of a cell?
Diffusion
The process by
which molecules
move from an
area of higher
concentration to
an area of lower
concentration.
Concentration =
the amount of a
substance in a
given volume.
Osmosis
The diffusion of water
molecules through a
selectively permeable
membrane.
Because cells cannot
function properly
without adequate
water, many cellular
processes depend on
osmosis.
Active Transport
The movement of
materials through a cell
membrane using cellular
energy (transport from
low to high
concentration).
Passive Transport
The movement of
dissolved materials
through a cell
membrane without
using cellular energy
(transport from high to
low concentration).
Diffusion is the
main method by
which small
molecules move
across the cell
membrane.
Take Notes!!
Diffusion in Action - What Does it Look Like?
Pure Water
Dilute Solution
0 kPa
Concentrated Solution
-200 kPa
Water Diffuses
from 0 to -200 kPa
-500 kPa
Water Diffuses
from -200 kPa to
-500 kPa
Diffusion in Action - Answer
Osmosis in Action - What Does it Look Like?
Low
concentration
of sucrose
High
concentration
of water
High
concentration
of sucrose
Low
concentration
of water
Osmosis in Action - Answer
What is it?
Ahem.wav
Effects of Osmosis on Cells
Osmosis can have important
consequences for a cell.
Red Blood Cells
Which diagram
represents the cells
in YOUR body???
Scream.wav
Plant Cells
Independent Work
Put Your Thinking Cap On!!
©BrainPOP
1. In what direction do molecules move during diffusion?
2. Suppose a permeable membrane separates sugar solutions
with concentrations with concentrations of 5 g/L and 7 g/L.
Which way will the sugar diffuse across the membrane?
3. Why is osmosis important?
4. How is osmosis related to diffusion?
5. Why can't people drink large amounts of salt or sugar water?
6. What happens in a cell once the concentrations of molecules
inside and outside the cell are equal?
©BrainPOP