Cell Transport
Passive and Active Transport
About Cell Membranes
1. All cells have a cell membrane
a.Functions:
o Controls what enters and exits the
cell
o Provides protection and support for
the cell
About Cell Membranes (continued)
2. Structure of cell membrane
a.The cell membrane is
made of two layers of
phospholipids called the
lipid bilayer
b.Proteins are also
embedded in cell
membrane
Phospholipid
Lipid Bilayer
About Cell Membranes (continued)
 3. Cell membranes have pores (holes) in it
a. the holes or pores makes the cell membrane
Selectively permeable: or Allows some
molecules in and keeps other molecules out
Pores
Structure of the Cell Membrane
Outside of cell
Proteins
Lipid
Bilayer
Transport
Protein
Animations
of membrane
Go to structure
Section:
Carbohydrate
chains
Phospholipids
Inside of cell
(cytoplasm)
Types of Cell Transport
1. Passive Transport
 cell doesn’t use energy
 HIGH  low concentrations
2. Active Transport
 cell does use energy
 LOW  high concentrations
Passive Transport
Characteristics



cell uses no energy
molecules move randomly
Molecules spread out from
an area of high
concentration to an area of
low concentration.
 (HighLow)
3 Different Types
1. Diffusion
2. Facilitated
Diffusion
3. Osmosis
Concentration Gradient
 Concentration gradient- the difference
in concentration of solutes or particles in
different places
1. Diffusion
Simple Diffusion
Animation
1. Diffusion: random movement of
particles from an area of HIGH
concentration to an area of low
concentration.
 Diffusion continues until all
molecules are evenly spaced or
have reached equilibrium
http://bio.winona.edu/berg/Free.htm
2. Facilitated Diffusion
Facilitated diffusion happens when specific
particles move through proteins found in
the membrane
 It is diffusion with the HELP of proteins in the
membrane
3. Osmosis
Osmosis
animation
Osmosis is ONLY the diffusion of water
through a selectively permeable membrane
 Water moves from high to low
concentrations
Solute/Solvent/Solution
 Solute – a SUBSTANCE dissolved in a fluid
 Solvent – the FLUID part of a solution
 Solution – a MIXTURE of two or more
substances (a solute and solvent)
Solute/Solvent/Solution
 This is sugar water.
 What is the solute?
 What is the solvent?
 What is the whole mixture
called?
Solute/Solvent/Solution
 A glass of iced tea.
 What is the solute?
 What is the solvent?
 What is the whole mixture called?
Solute/Solvent/Solution
 Ex: Dr. Pepper
 What is the solute(s)?
 What is the solvent?
 What is the whole mixture called?
•
Hypotonic Solution
Hypotonic: A solution that
has a lot of water and that
water moves INSIDE the cell
making it swell
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
•
Hypertonic Solution
 Hypertonic: The solution
has MORE solutes and a
lower concentration of
water
 The water will move OUT of
the cell making it shrink or
crenate
shrinks
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
•
Isotonic Solution
 Isotonic: The concentration of solutes and
water in solution and in the cell are EQUAL
 Water moves equally in both directions and
the cell remains same size!
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
What type of solution are these cells in?
A
B
C
Hypertonic
Isotonic
Hypotonic
Overcoming Osmosis
 Contractile vacuoles – structure that will
expel excess water from unicellular organisms
that live in water. (like Paramecium!)
 Turgor pressure – water pressure in a plant
cell when a plant is placed in a HYPOtonic
solution. A loss of turgor pressure causes
wilting (plasmolysis).
Paramecium (protist)
removing excess water
video
Active Transport
Characteristics
• cell uses energy
• actively moves molecules to
where they are needed
• Movement from an area of
low concentration to an
area of high concentration
• Goes AGAINST the
concentration gradient
2 Types of Active
Transport
1. Endocytosis
2. Exocytosis
Types of Active Transport
1.
Endocytosis:

taking bulky material into
a cell
• Uses energy
• Cell membrane fold in around
food particle
• forms food vacuole & digests
food
• This is how white blood cells
eat bacteria!
Types of Active Transport
2.
Exocytosis “leaving the cell”
 Forces material out of cell in bulk
• membrane surrounding the
material fuses with cell
membrane
• Cell changes shape – requires
energy
• EX: materials or wastes are
released from cell
Endocytosis &
Exocytosis
animations
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