Download Plasma Membrane

Plasma Membrane
 Responsible for homeostasis
Plasma membrane
• Thin, flexible boundary between a cell and its
environment. Allows nutrients in and allows
waste to leave cell
• Plasma membranes have Selective permeability:
allows some substances to pass through while
keeping others out.
• A cell membrane is called a fluid mosaic because
it behaves more like a liquid than a solid.
Structure of Plasma Membrane
• Cell membranes are made of a lipid bi-layer.
(double layer)
• A single phospholipid molecule has two
different ends: a head and a tail.
• The head end contains a phosphate group and
is hydrophilic. This means that it likes or is
attracted to water molecules.
• Phosphate group makes the head polar and is
attracted to water ( water also polar)
Structure of Plasma Membrane
• The tail end is made up of two strings of
hydrogen and carbon atoms called fatty acid
chains.
• The tail is hydrophobic or do not like to mingle
with water molecules
• 2 fatty acid tails are nonpolar and are repelled
by water
•
Inside
Plasma
Membrane
Cholesterol, proteins, and carbohydrates move among the
phospholipids.
• Proteins: transmit signals, anchor the cells
• Transport protein: tunnel for certain substances to enter
and leave cell( aid movement of substances)
• Cholesterol: helps the fatty acid tails from sticking together.
( structure)
• Carbohydrate chain: define cells characteristics and help
cells identify chemical signals(recognition marker)
• Enzymes: biochemical reactions within the cell
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