Download The Cell Membrane

YOUTUBE Membrane Rap
Membrane Rap
The Cell Membrane
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Why do cells need membranes?
What functions does it perform?
1.
Keep the overall structure of a
cell.
Keeps things in the cell (ex.
Cytosol, organelles).
Keeps things out (ex. Toxins,
excess water).
Movement.
2.
3.
4.
What kind of things move
across this membrane?
Some examples:
 Sugars
Charged ions (+/-)
H2O
 O2
CO2
What are some ways
molecules move across the
cell membrane?
Passive Transport!
1. Simple Diffusion
2. Facilitated Diffusion
3. Osmosis
ENDOcytosis and EXOcytosis!
1. Phagocytosis
2. Pinocytosis
3. Receptor Mediated Endocytosis
Require no
chemical
energy!!!
1. Simple Diffusion
Unassisted diffusion!
The solutes transported with way are either
(in order to pass through our LIPID bilayer)
or are
enough to pass through the membrane
pores.
2. Facilitated Diffusion
The transporting of substances across the cell
membrane from an area of
to an
area of
by means of a carrier
molecule. In the cell membrane these are
!
3. Osmosis
Osmosis is the diffusion of water molecules. Water
molecules diffuse across a semi permeable membrane
(the cell membrane) from a region of
concentration to an area of
concentration.
Endocytosis
Endocytosis is a process in which single-celled
organisms take in substances such as large polar
molecules that cannot cross the hydrophobic plasma
membrane.
In endocytosis the cell ingests substances by
and surrounding the
food particle.
1. Phagocytosis
The material taken in by the cell is a
such as bacterium or a fragment of organic matter.
2. Pinocytosis
If the material taken in by the cell is
is known as pinocytosis.
the process
3. Receptor Mediated
Endocytosis
This applies to specific molecules (ex. Low Density
Lipoproteins). Molecules to be transported first bind to
on the plasma membrane (receptor
proteins). The interior portion of the receptor protein is
embedded in the membrane. The protein clathrin coats
the inside of the membrane in the area of the pit. When
an appropriate collection of molecules gather in the
coated pit, the pit deepens and seals off to form a coated
vesicle which carries the molecule into the cell.
Exocytosis
JUST THE REVERSE!!
Exocytosis is the reverse of endocytosis. This process
results in the discharge of material from vesicles at the
cell surface to the outside of the cell.