Download Chapter 2, Lesson 3

CHAPTER 2, LESSON 3
Moving Cellular Material
• How do materials enter and leave
cells?
• How does cell size affect the transport
of materials?
Lesson 3 Vocabulary
• Passive transport
• Diffusion
• Osmosis
• Facilitated diffusion
• Active transport
• Endocytosis
• exocytosis
Quick Review of properties of the
Cell Membrane
• Forms the boundary between cells and between
organelles
• Controls the movement of substances into and our of cells
• How it does this depends on:
• Physical properties of the substance passing through
• Chemical properties of the substances passing through
• Semipermeable – will allow only certain substances to
enter or leave a cell
Transporting Substances happens in 2
main ways:
I. Passive Transport
• The movement of substances
through a cell membrane
WITHOUT USING THE
CELL’S ENERGY
II. Active Transport
• The movement of
substances through a cell
membrane only BY USING
THE CELL’S ENERGY
I. Passive Transport
• When can a cell move substances across the cell
membrane using passive transport?
1. If the molecules are small
2. When there are MORE molecules of a substance on one side of
the membrane than on the other side
Types of Passive Transport
1.
Diffusion – the movement of substances from an
area of higher concentration to an area of lower
concentration
2.
Osmosis – the diffusion of WATER molecules
through a membrane
3.
Facilitated Diffusion – when molecules pass
through a membrane using special proteins called
transport proteins
Assignment for tomorrow:
• Read pages 62-65. Label and answer the following
questions in your notebook. Please write in complete
sentences and re-state the questions.
• VC-p. 62
• RC-p. 63
• KCC-p. 64
• KCC-p. 65
“What would the water in the beaker on the right
look like if the membrane did notlet anything
through?” VC-p. 62
• The water on the right side would
remain clear.
• Think about these questions:
• How would you describe the concentration of red dye molecules on
each side of the membrane in the first beaker?
• Why did the dye molecules move into the right side of the beaker?
• What would the beaker look like if there was another picture taken
after 60 minutes? Why?
“How do materials move through the cell
membrane in facilitated diffusion?” RC-p. 63
• Transport proteins called channel proteins and carrier
proteins move materials through the cell membrane in
facilitated diffusion.
Facilitated Diffusion
• Used when molecules are too large or chemically
unable to travel through a cell membrane
• Does NOT require cell to use energy
• Transport proteins are used to get the molecules across
• Two types of transport proteins
• Carrier proteins
• Channel proteins
2 Types of Transport Proteins
Carrier Proteins – “think ferry boat”
• Carry large molecules through
the cell membrane
Channel Proteins – “think tunnel”
• Form pores through the cell
membrane
II. Active Transport
• The movement of substances through a cell
membrane only BY USING CELL’S ENERGY
• Second way materials can pass into or out of a cell
• Used when moving substances from areas of LOWER
CONCENTRATION TO HIGHER CONCENTRATION
2 Types of Active Transport
Endocytosis
Exocytosis
• The process during which
• The process during which
a cell takes IN a
substance by surrounding
it with the cell membrane
a cell’s vesicles release
their contents OUTSIDE
the cell
https://www.youtube.com/watch?v=D
uDmvlbpjHQ
“How do materials enter and leave
cells?” KCC-p. 64
• Materials enter and leave cells through the cell
membrane using either PASSIVE TRANSPORT, such
as diffusion, osmosis or facilitated diffusion; OR
ACTIVE TRANSPORT, including endocytosis and
exocytosis.
“how does cell size affect the transport
of materials?” KCC-p. 65
• As a cell becomes larger, its volume increases faster
than its surface area, making the transport of enough
materials to support the cell more difficult.
Milk can be easily transported in
this picture
As the size of the community
grows, it gets much harder to
transport milk to the whole
community
By splitting up the community,
milk can, once again, be
transported efficiently