Transcript Biochemistry: Chemicals of Life

Cell Membrane
Objectives
 Summarize the main functions of a cell
membrane.
 List and illustrate the main structures of a cell
membrane, in terms of phospholipids,
proteins and carbohydrates.
 Compare and contrast cell membranes to cell
walls.
Cell Membrane
A cell
membrane
has 3 main
functions
Functions
 Controls what enters / exits cell.
 Protects cell.
 Supports cells.
Cell membrane surrounds cell.
Cell Membrane
A cell
membrane is
made of 3
types of
organic
molecules
Structure
 Phospholipid bilayer
 Proteins (integral and peripheral)
 Carbohydrates
Cell Membrane
Phospholipid
bilayer
Most of a cell membrane is made of a
phospholipid bilayer
Double layer of phospholipid molecules.
Fluid and flexible.
Allows some small, non-polar molecules
through, but blocks large or charged
molecules.
Cell Membrane
Phospholipid
molecules have
a “head” and a
“tail”
Phospholipid molecules arrange themselves into
bilayer because of their special structure.
Hydrophilic
head “loves”
water.
Hydrophobic
tail “fears”
water.
Cell Membrane
Integral and
peripheral
proteins
Proteins are attached to phospholipid bilayer
and perform many functions:
 Integral proteins are attached to membrane.
They can transport materials or carry signals in
and out of the cell.
 Peripheral proteins temporarily attach to
phospholipid bilayer or integral proteins.
Cell Membrane
Carbohydrates
Some carbohydrate chains are attached to the
membrane surface. These help cells identify
and recognize each other.
Cell Membrane
Cell Wall
A cell wall is a hard, flexible extra layer
surrounding the cell membrane in some
organisms, including:
 Plants
 Fungi
 Some bacteria
Exit Ticket
1. Summarize the main functions of a cell membrane.
The main functions of a cell membrane include…
2. List and illustrate the main structures of a cell membrane,
in terms of phospholipids, proteins and carbohydrates.
The main structures of a cell membrane includes…
Illustration of cell membrane: …
3. Compare and contrast cell membranes to cell walls.
In comparison, a cell membrane and cell wall both _______________________.
In contrast, a cell membrane is _____________________________________________,
while a cell wall is ___________________________________________________________.