Transcript Cellular Functions

Cellular Functions
Biology Agriculture
Movement of Materials
Diffusion
Osmosis
Passive Transport
Active Transport
Hypotonic Solution
Hypertonic Solution
Isotonic Solution
Endocytosis
Exocytosis
Group Assignment
What is the function?
Describe it and teach the class how that
function works.
How does it affect what happens in the cell?
Give some examples of that cell function in real
world application.
You must have photos, diagrams and images of
the function organized on a poster.
You are required to come up with a lab for this
presentation.
Movement of Materials
All molecules are governed by the same
physical laws.
Knowing how they work will better help
you understand cells.
Diffusion
The process by which molecules of a
substance move from areas of high
concentration to areas with a low
concentration.
i.e. food coloring in water.


Food coloring is the high concentration
Water is the low concentration.
Equilibrium
Concentration Gradient:

The difference in the concentration of
molecules of a substance from highest to
lowest.
Equilibrium:

When the concentration gradient equalizes.
Plasma Membranes
Acts like a barrier
Membranes control the passage of
materials in and out of the cell.
They are selectively permeable:

They allow only certain substances to pass
through them.
Osmosis
The diffusion of water across a selectively
permeable membrane.
Living Cells
Isotonic Solution
Hypotonic Solution
Hypertonic Solution
Isotonic Solutions
The rate of osmosis into the cell is exactly
the same as the rate leaving the cell.
As a result, no water movement takes
place.
Hypotonic Solutions
Water moves from the solution into the cell
From a higher concentration to a lower
concentration.
Fresh water plants often exist in hypotonic
solutions. As water moves into their cells,
the cell swells and increases in internal
pressure, called turgor pressure.
Turgor Pressure
The force of the cell contents pushing
against the cell wall.
Excess water entering a plant is stored in
a large vacuole.
This pressure in the cell pushes against
the cell wall causing the cell to become
stiff and rigid.
Hypotonic Solution
Animal cells do not have a cell wall,
therefore, as water flows into the cell until
it bursts.
Animal cells have developed a way to
remove excess water.
Animal cells use their vacuoles remove
water from the cell.
Hypertonic Solution
The concentration of water in the cell is
lower then the surrounding solution.
The result;

Cells shrivel up and loose its shape because
more water flows out of the cell then into the
cell.
Living Cells – Concentration
Gradients
Hypotonic
Isotonic
Hypertonic
Lower outside
the cell
Equal outside
the cell
Greater outside
the cell
Greater inside
the cell
Equal inside
the cell
Lower inside
the cell.
Cell contents
swell
Cell contents
stay the
same
Cell contents
shrink
Homeostasis
The ability of an organism to maintain a
constant internal balance even when the
conditions around it change.
Passive Transport
The movement of molecules through the
cell membrane without using energy.
Active Transport
The movement of molecules from areas of
lower concentration to areas of higher
concentration with the use of energy.
Endocytosis
Cell membrane encloses a substance or
particle, forming a pouch.
The pouch is drawn into the cell.
Then pinched free of the cell membrane.
Exocytosis
Reverse of Endocytosis
Substances to be removed from the cell
are enclosed in a vacuole
Vacuole moves to the cell membrane and
fuses
The content of the vacuole are then
expelled from the cell.