Download The Plasma Membrane

THE PLASMA MEMBRANE
Period 3 honors
By:
Kristian Rolin
Chase Denton
Qwazia Lainer
WHAT IS IT?
The plasma membrane is the boundary between the cell and
its environment. It regulates what enters and exits the cell.
Cells must maintain an appropriate amount of molecules to
function inside them. They must also have a way to keep things
out or to allow things to enter. This is the job of the plasma
membrane. The plasma membrane is like the guard at a
gated community. The guard must inspect those who enter and
those who leave to make sure that only the people and things
needed in the community are there.
https://www.youtube.com/watch?v=LKN5sq5dtW4
COMPONENTS OF THE PLASMA MEMBRANE
 Like all other cellular membranes, the plasma membrane consists of both lipids and proteins.
 The structure of the membrane is the phospholipid bilayer, which forms a stable barrier between two aqueous compartments.
 In the plasma membrane, these compartments are the inside and the outside of the cell.
 Proteins embedded within the phospholipid bilayer carry out the specific functions of the plasma membrane.
https://www.youtube.com/watch?v=mtDm2OKIK1k
DIAGRAM
https://www.youtube.com/watch?v=Pfu1DE9PK2w
HOMEOSTASIS
The plasma membrane maintains homeostasis by keeping cell contents in and foreign
material out
Provides controlled avenues for the transportation of fuel, fluid and waste.
"Homeostasis" means "same state."
Cells in homeostasis are successfully maintaining the internal conditions necessary for
basic functioning.
The plasma membrane is essential for maintaining these conditions functioning.
Simply, the plasma membrane separates the inside of the cell from the outside.
Without it, a cell is nothing more than a popped balloon, spilling its contents out into
space.
HOW SUBSTANCES ENTER AND EXIT THE CELL
Selectively permeable cell membranes allow certain molecules or ions to pass
through it by active or passive transport.
Active transport processes require the cell to expend energy to move the materials,
while passive transport can be done without using cellular energy. Note that the
membrane can also block the passage of materials depending on the conditions
inside or outside of the cell.
The method used by a cell to pass molecules in or out is determined by the size of the
molecule, as well as the concentration of the molecules on the inside and outside of
the cell. Most cell membranes are covered with tiny protein channels that allow things
to move in and out of the cell. These act as gateways.
If a molecule is tiny enough to fit through a special protein channel, it will use a form
of active or passive transport to move through. If the molecule is too large to fit
through a protein channel, it will have to enter or exit the cell by forming a vesicle.
HYPOTONIC HYPERTONIC AND ISOTONIC SOLUTIONS
Plasma membranes are made up of a phospholipid bilayer. Phospholipids are chains
of fatty acids attached to a phosphate group. "Bilayer" means two layers. When
phospholipids get together, they form a double layer, with their phosphate groups
facing out and their fatty tails pointing toward one another. The fatty interior of this
layer is "hydrophobic" because it repels water. The surrounding phosphates are
called "hydrophilic" because they come into contact with fluid inside and outside the
cell. The plasma membrane separates these two sets of fluids and their contents.
https://www.youtube.com/watch?v=m2xg9MzwqxA
FLUID MOSAIC MODEL
https://www.youtube.com/watch?v=Qqsf_UJcfBc
https://www.youtube.com/watch?v=Qqsf_UJcfBc
A model that describes the structure of
cell membranes. In this model, a flexible
layer made of lipid molecules is
interspersed with large protein molecules
that act as channels through which other
molecules enter and leave the cell.
REVIEW
The primary function of the plasma membrane is to protect the cell from its
surroundings.
To maintain an equilibrium the plasma membrane goes through homeostasis
The plasma membrane acts as a barrier that only allows certain substances to enter
and exit the cell through active and passive transport
ANY QUESTIONS?
QUESTIONS
What is the function of the plasma membrane?
Why is the plasma membrane described as a “fluid mosaic”
Which of the following types of molecules are the major structural components of the
cell
membrane?
a. phospholipids and cellulose
b. nucleic acids and proteins
c. phospholipids and proteins
d. proteins and cellulose
e. glycoproteins and cholesterol
WORK CITED
http://www.phschool.com/science/biology_place/biocoach/biomembrane1/solutions
.html
http://biology.tutorvista.com/animal-and-plant-cells/plasma-membrane.html
http://study.com/academy/lesson/plasma-membrane-of-a-cell-definition-functionstructure.html
http://biology.tutorvista.com/animal-and-plant-cells/plasma-membrane.html
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF8#q=google+images