Download Cell Membrane - Seekonk High School

Homeostasis
Cells must maintain
homeostasis in order to live
One way is by controlling the
movement of water through the
cell membrane
Cell Membrane
A fluid sea of lipids in which
proteins float
Allows only some materials to
enter the cell
Phospholipid
Specialized
lipid made of a
phosphate head
and two fatty
acid tails
Lipid Bilayer
Phospholipids form a lipid
bilayer
One polar head faces the
cytoplasm
Other polar head faces outside
Lipid Bilayer
Barrier
The phospholipids form a
barrier through which only
small, nonpolar substances can
pass.
Proteins
Nonpolar parts are attracted to
inside of lipid bilayer
Polar parts are attracted to
outside
Types of Proteins
Cell-surface markers – identify
each type of cell by the kind of
sugars
Attached to the surface by
glycoproteins
Types of Proteins cont.
Receptor Proteins – enable the
cell to sense its surroundings by
binding to certain substances
outside the cell
Causes changes in cell
Types of Proteins cont.
Enzymes – Proteins in the cell
membrane help with important
biochemical reactions in the cell
Types of Proteins cont.
Transport Proteins – Many
substances the cell needs
cannot pass through the lipid
bilayer
Proteins aid the movement of
these substances in and out of
the cell