Cellular Transport
The Cell Membrane
• Remember: ALL cells have a cell membrane!
• Remember its function: To act as a boundary
between the inside of the cell and the outside of
the cell. It protects the cell by keeping the good
things in and the bad things out!
• This boundary maintains an internal balance in the
cell called HOMEOSTASIS.
• The cell membrane has holes in it, like how our skin
has pores. This is called being SELECTIVELY
PERMEABLE. It allows some things in and keeps
other things out.
Types of Cellular Transport
• Passive Transport- the cell does NOT use
energy
1. Diffusion
2. Osmosis
• Active Transport- the cell USES energy
1. Endocytosis
2. Exocytosis
Passive Transport
• The cell uses NO energy
• Molecules spread from an area of
HIGH concentration to an area of
LOW concentration
Weeee!!!
• HIGH  LOW
high
low
PASSIVE TRANSPORT  Diffusion
and Osmosis
• Diffusion is movement of particles from an area of
high concentration to an area of low concentration.
• Molecules continue to spread out until equilibrium
is reached.
• Osmosis is simply diffusion of WATER across a
membrane.
Active Transport
• The cell USES ENERGY
• Molecules spread from an area of
LOW concentration to an area of
HIGH concentration
• LOW  HIGH
high
low
This is
gonna be
hard
work!!
ACTIVE TRANSPORT  Endocytosis
• Uses energy!
• The cell engulfs something outside of it and
takes it INTO itself.
• This is how white blood cells eat bacteria!
• VIDEO
ACTIVE TRANSPORT  Exocytosis
• Uses energy!
• FORCES material outside of the cell
• This is how hormones or wastes are
released from the cell
• VIDEO