Download Cell Membrane and Transport

What is an Isotonic Solution?
• [Water] inside cell =
[Water] outside cell
• Cell is at equilibrium
– Molecules are equally
distributed in end
• The amount of water
entering the cell = the
amount of water
leaving the cell
95%
water
95%
water
What is a hypotonic solution?
• A solution that has
MORE water, and
LESS solute
• The cell can lyse or
burst if left in a
hypotonic solution
100%
water
95%
water
What is a hypertonic solution?
• A solution that has
LESS water and MORE
solute
• The cell will dehydrate
90%
water
95%
water
Which direction does water flow?
a) Water doesn’t flow at all.
b) Water flows from an area of low
concentration to an area of high
concentration.
c) Water flows from an area of high
concentration to an area of low
concentration.
Lipids
• Lipids function in:
– Energy (E) storage,
– forming cell membranes,
– and as chemical messengers
(e.g., hormones)
• Nonpolar (hydrophobic)
• Made up mostly of Carbon and Hydrogen
(with a few Oxygen)
Lipids
1. Fats (Triglycerides)
– Glycerol + 3 Fatty Acids
– Saturated = No Double Bonds (solid)
– Unsaturated = Double Bonds (liquid)
OH
OH
OH
OH
OH
Ester Bonds
OH
Organic Compounds: Lipids: Phospholipids
Lipids
2. Phospholipids
– Glycerol with Phosphate Head +
2 Fatty Acid Chains
– Amphiphilic (“Both” “lover”)
•
•
Hydrophilic headPhosphate
Hydrophobic tail
Glycerol
– Forms 2 layers in water
– Makes up cell membranes
Fatty Acids
Egg lab
• Dissolve egg shells
• Rinse
• Calculate initial mass
The plasma/cell membrane is selectively
permeable
~only certain substances are allowed to
pass through
What can and can not pass
through the membrane?
CAN PASS THROUGH
• Things that can
dissolve in fat
• Small molecules
• Water
CAN NOT PASS THROUGH
1. Things that can dissolve in
water
2. Large molecules
3. Ions: Molecules with plus
(+) or minus (-) charges
CH2OH
OH
There are three types…
No energy is used
[High]  [Low] (it’s the natural flow)
This means it goes down a concentration gradient
3 types of Passive Transport
1. Diffusion
2. Osmosis
3. Facilitated Diffusion
Diffusion
[High]  [Low]
Osmosis
+
CH2OH
Facilitated Diffusion
OH
Passive Transport: Facilitated Diffusion
There are three types…
Energy is used
[Low]  [High]
This means it goes up or against a
concentration gradient
3 Examples of Active
Transport
1. Protein pumps
2. Endocytosis
3. Exocytosis
Protein Pumps
Protein Pumps: proteins use energy to pull or
pump materials into or out of the cell to
stockpile or store substances the cell needs
Endocytosis
•
•
When cells engulf particles into the cell
2 types
1. Phagocytosis: When a cell wraps part of its
membrane around
a large particle
forming a “pocket”
or vesicle
2. Pinocytosis: The
same process,
but with smaller
particles or liquids
Exocytosis
1. A vesicle carrying a
substance
2. fuses with the cell
membrane
3. and releases the
substance