Transcript Chapter 2, Section 2 The Cell in Its Environment

Chapter 2, Section 2
The Cell in Its Environment
Monday, October 5, 2009
Pages 56 -- 60
Objectives
Describe the three methods by which
materials move into and out of cells.
Compare passive transport to active
transport.
Explain why cells are small.
Vocabulary Words
Selectively permeable
Diffusion
Osmosis
Passive transport
Active transport
Diffusion Demo
Think about the following as you
observe the demonstration:
Why did the water in the bag turn purple?
Why didn’t the water in the cup turn
purple?
Gatekeeper
The cell membrane serves as a gatekeeper.
Some substances are allowed in while others are
kept out.
Substances move into and out of a cell
through one of these three methods:
Diffusion
Osmosis
Active transport
Diffusion
QuickTime™
QuickTime™
andand
a a
TIFFTIFF
(Uncompressed)
(Uncompressed)
decompressor
decompressor
are are
needed
needed
to see
to see
thisthis
picture.
picture.
It is the process by which molecules move from a
higher concentration to a lower concentration.
What causes diffusion and how does it work?
Osmosis
QuickTime™ and a
QuickTime™ and a
TIFF (Uncompressed) decompressor
TIFF (Uncompressed) decompressor
are needed to see this picture.
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Normal shape of
red blood cell.
Cell has shrunk because
water has moved out by
osmosis.
Cell is swollen with
water that is moved in
by osmosis.
Osmosis is the diffusion of water molecules
through a selectively permeable membrane.
Active Transport
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Active transport
requires the use of
energy to move
materials through a
cell membrane.
Passive transport
does not require the
use of energy.
Active Transport Proteins
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
These are also known
as ATPs.
Their role is to “pick-up”
molecules outside the
cell and carry them in
using energy.
Calcium, potassium,
and sodium are
examples of molecules
that must be carried in.
Engulfing
Engulfing is another
form of active
transport.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Why are cells so small?
Think about the organization of
organelles within the cell.
Think about the cytoplasm.
Homework
Workbook 2.2 -- Due on Wednesday,
10/7.
Vocabulary Quiz--Sections 1 and 2 on
Wednesday, 10/7.
REMINDER: Lab write-up due on
Tuesday, 10/6.