Warm up
• The cell membrane is called phospholipid
bilayer.
– What is a phospholipid?
– Which part of the phospholipid is hydrophobic?
– Which part of the phospholipid is hydrophilic?
– Define the term semi-permeable.
– Quiz in 5 min.
Notes: Passive Transport
Ch. 5 Pg 97-102
Cell Transport
• Molecules cross
membrane in several
ways
– Some methods of
transport require
energy and some do
not.
– Depends molecules
size, polarity, and
concentration inside
versus outside.
Cell Transport
• Small molecules and larger hydrophobic molecules
move through bilayer easily.
– e.g. O2, CO2, H2O
Cell Transport
• Ions, hydrophilic molecules, and large molecules do
not move through the membrane on their own.
– e.g. Na+, K+
Passive Transport
• Movement across the
membrane WITHOUT
the use of energy
Concentration Gradient
• Molecules have kinetic
energy
• Concentration
Gradient: difference
between high and low
concentration
• Molecules move “down”
gradient without energy
• Equilibrium - when all
molecules are evenly
spread out
• Draw this!
Types of Passive Transport
1. Diffusion: Movement of molecules from high to low
concentrations.
Types of Passive Transport
2. Facilitated Diffusion:
Molecules too big to
move across the
membrane use carrier
proteins
• Ex. Glucose
Types of Passive Transport
3. Osmosis: diffusion of
water across membrane
• Water moves where
there are more
solutes.
• Solute: What gets dissolved.
• Solvent: What the Solute
dissolves in.
• Solution: The mixture of the
solute and the solvent.
Which way will the water move?
Types of Tonicity
1. Hypotonic
• More solutes inside the cell, water moves in
• The cell swells
Draw These
Animal Cell
Plant Cell
Hypertonic
• More solutes outside the cell, water moves out
the cell
• The cell shrinks
Animal Cell
Draw these!
Plant Cell
Isotonic
• Equal solutes inside and outside
• Water moves in and out at the same rate
• Cell stays the same
Draw These!
Animal Cell
http://www.youtube.com/watch?v=OYoaLz
obQmk&index=2&list=PLexD8cl0p1Z8r4WyQXQ6R6-Hg81nERSg
Plant Cell