1. The Cell in Action!!!
STATE UNIVERSITY OF SURABAYA
By: Ms. Dhita

2. Section 1 Objectives:
•Explain the process of diffusion
•Describe how osmosis occurs
•Compare passive transport with active
transport
•Explain how large particles get into
and out of cells

3. Exchange with the Environment
An organism must be able to obtain energy and
raw materials and get rid of waste.
Cell division allows organisms to grow and repair
injuries.
Exchange of materials between a cell and its
environment takes place at the cell’s membrane.

4. Everything is made up of moving particles.
Particles travel from where they are crowded to
where they are less crowded.
This movement from areas of high concentration
(crowded) to areas of low concentration (less
crowded) is called DIFFUSION
Cells do not need energy to use energy for diffusion
What is Diffusion?

5. Example of Diffusion

6. Diffusion of Water
Cells of organisms are surrounded by and filled with
fluids that are made mostly of water.
OSMOSIS – the diffusion of water through cell
membranes
Water is made of up molecules
Pure water has the highest concentration of water
molecules, but when you mix something, you lower the
concentration of water molecules.

7. Osmosis Continued…
Semipermeable means only certain substances can
pass through
If certain substances pass through a semipermeable
membrane, over time the water molecules move
from the liquid with the high concentration of water
to the liquid with low concentration of water
molecules.

8. Osmosis Example

9. The Cell and Osmosis
The Animal Cell
Plasma (surrounds red
blood cells) is made up of
water, salts, and sugars.
Concentration of these
particles is kept in
balance by osmosis.
The Plant Cell
Osmosis occurs in plant
cells
When a wilted plant is
watered, osmosis makes
the plant firm again!

10. Hypotonic, Isotonic, & Hypertonic Solution
 If environment is:
 Hypertonic:
 MORE SOLUTES outside cell
 MORE WATER IN CELL
 over time, cell loses water
 Isotonic:
 “Iso-” means environment “=” cell
 No change in cell volume
 Hypotonic:
 LESS SOLUTES outside cell
 LESS WATER IN CELL, more solutes in cell.
 over time, cell gains water

11. Comparison of 3 Types of Solutions
HYPHYPERERTONICTONIC ISOISOTONICTONIC HYPHYPOOTONICTONIC

12. Moving Small Particles
Small particles, such as sugars, cross the cell membrane
through passageways called CHANNELS.
Channels are made up of proteins in the cell membrane.
Particles travel through the channels either through:
 Passive Transport
 Active Transport

13. Passive Transport
Movement of particles across
a cell membrane without the
use of energy by the cell.
Particles move from an area
of high concentration to an
area of low concentration.
Diffusion and Osmosis are
examples of Passive
Transport!
Active Transport
Process of transporting
particles that requires
the cell to use energy.
Usually involves the
movement of particles
from an area of low
concentration to an area
of high concentration!

14. Moving Large Particles
Large particles move into and out of the cell by
processes called:
 Endocytosis = “Within the Cell”
 Exocytosis = “Outside the Cell”

15. Endocytosis
 Active transport process that surrounds a large particle.
 Encloses the particle in a vesicle.
 Brings the particle into the cell.
 2 types of endocytosis:
 Fagocytosis
 Pinocytosis
 Receptor-Mediated Endocytosis
 What are Vesicles??
 Sacs formed from pieces of cell membrane

16. Receptor-Mediated Endocytosis

17. Exocytosis
Active transport which moves large particles out of
the cell.
A vesicle forms around a large particle within the
cell.
Vesicle carries the particle to the cell membrane.
Vesicle fuses with the cell membrane and releases
the particle to the outside of the cell.

18. Quiz . . .
Describe Diffusion!
Describe Osmosis!
What is the difference between active
transport and passive transport!
Endocytosis means…?
Exocytosis means…?