Download The Cell Membrane

The Cell Membrane
Aka: plasma membrane
What is the cell membrane made
of?
2 layers of phospholipids
Carbohydrate & proteins embedded in the
lipids.
The phospholipids
Fluid Mosaic Model
Questions…
• What is the MAJOR component (part) that
makes up the cell membrane?
• What is the name of the model we use to
show the structure of the cell membrane?
2 types of proteins
1) Integral – usually go completely through
the membrane, act as channels.
2) Peripheral – usually on the surface, act
for communication or attachment sites.
Can everything pass through the
cell membrane?
NOPE!
The cell membrane is selectively
permeable, only certain things are let
through.
Question…
• Which type of protein in a cell membrane
is used to help the cell communicate with
other cells with neurotransmitters or
hormones?
2 main forms of transport across
the cell
1) Active – requires energy, usually moves
substance against a gradient.
2) Passive – does not need energy, usually
moves substances down the gradient.
What are the different types of
active transport?
1) Pumps - protein channels assist in the
movement of substances.
EX: Na-K pump
2) Exocytosis
Moves large molecules
or amounts OUT of
the cell
3) Endocytosis
Moves large molecules
or amounts into the
cell.
Passive transport
With passive transport, the goal is
EQUILIBRIUM.
Once equilibrium is reached there is no NET
MOVEMENT.
Types of passive transport
1) Diffusion – movement of a substance
through a semi-permeable membrane
from an area of higher concentration to an
area of lower concentration.
diffusion
2) Osmosis
Movement of water down a concentration
gradient.
Water moves TOWARDS hypertonic areas
Hypertonic
A cell put in a
hypertonic solution
will shrink!!!
Hypotonic
A cell put in a hypotonic
solution will swell and
may burst!
Isotonic
When the concentration
gradient across the
membrane is the
same, there is no
NET movement. The
cell will stay the
same.
Question…
• If a cell is put in a glass of REALLY sugary
water, will the cell shrink or swell?
3) Facilitated diffusion
Carrier proteins help move substances across the
membrane.
Questions…
• Are pumps active or passive?
• Is diffusion active or passive?
• Is osmosis active or passive?
cell transport