Download The Plasma Membrane aka the cell membrane http://sun

The Plasma Membrane
aka the cell membrane
http://sun.menloschool.org/~cweaver/cells/c/cell_membrane/
Cell membrane Facts
• 1. Serves as "gateway + barrier for cell"
• 2. Made up of phospholipids and proteins.
• 3. Separates the contents of the cell from
the external environment.
• 4. It is extremely thin (you could stack
10,000 plasma membranes to equal the
thickness of a piece of paper).
The Cell membrane functions to:
• Control what goes in and out of a cell.
• Anchors the cytoskeleton to help provide shape.
• Attaches to a substrate outside of the cell or to other
cells to help form tissues
• Controls the transportation of substances across the
membrane by using proteins as carriers and
channels
• Contains receptors that allow cells to communicate
through chemical messages
• Contains recognition proteins which help identify the
cell, so the immune system does not attack it.
Phospholipids
• Has a hydrophilic
(water loving
head)
• Hydrophobic
(water fearing)
Tail
• Made up mostly
of carbon (black)&
Hydrogen (light
blue)
Phospholipid bi-layer
• The cell membrane is
made up of 2 layers
of phospholipids.
• The Hydrophilic
heads face out.
• The Hydrophobic tails
face inward
Other Membrane components
Cholesterol makes the cell membrane more
stiff and less permeable.
Membrane Proteins function to:
• Transport proteins – regulate the movement of
water-soluble molecules through the cell
membrane.
• Receptor proteins –recognizes and binds to
specific molecules. Often trigger some response
by the cell such as endocytosis or cell division.
• recognition proteins – identifies the cell as
belonging to a specific species or organ. Helps
immune system tell invading cells from cells
belonging to the organism.