1.3 diffusion, osmosis, and the cell membrane...
TRANSCRIPT
1.3 Diffusion, Osmosis, and the Cell Membrane
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1.3 Diffusion, Osmosis, and the Cell Membrane
• Diffusion: the movement of particles from an area of higher concentration to an area of lowerconcentration.
• Concentration [ ] is the amount of substance in a given space.
• Example: smell of fresh baked bread “spreading” throughout the room is an example of diffusion.
Diffusion and the Cell Membrane
• The cell membrane is a selectively permeable membrane.
It has many small openings that let some substances pass through it
but not others.
• One way that substances can move through the cell membrane is
by diffusion.
• When the concentration on both sides of the membrane is the
same, it is called equilibrium.
Osmosis
• Osmosis is the diffusion
of water through a
selectively permeable
membrane.
• Osmosis occurs when
water particles move
from a higher
concentration to a
lower concentration.
Osmosis and the Cell
• Cells contain water and need this water to survive.
• Osmosis is how the cell gains and loses its needed
water.
Explain how placing this wilted
flower in water will cause the flower
to “straighten up”.
Examples of Osmosis
Example 1: Equal movement of water in and out of cells
Examples of Osmosis
Example 2: More water moving into cells than is moving out
Examples of Osmosis
Example 3: More water moving out of cells than is moving in
Cell reproduction/growth and
• Read the handout provided.
Answer the following questions
What are 2 reasons why cells divide rather than continue to
grow indefinitely.
Cells reproduce by cell division.
What are the phases of mitosis? Draw a diagram and label
what is happening in each step.
(c) McGraw Hill Ryerson 2007
(c) McGraw Hill Ryerson 2007
Early Prophase - nucleolus disappears and spindle fibres form
Late Prophase - spindle fibres attach to centromeres of
chromosomes
Metaphase - chromosomes align on equator of cell
Anaphase - spindle fibres pull sister chromatids to opposite poles of
cell
Telophase - in this final stage, spindle fibres disappear and a
nuclear membrane forms around each separated set of
chromosomes.
Cytokinesis is the separation of the nuclei into two daughter cells
• https://www.youtube.com/watch?v=ofjyw7ARP1c
(c) McGraw Hill Ryerson 2007
Assignment
• Cell lab next class
• Cell structure test Wednesday Oct. 26.
(c) McGraw Hill Ryerson 2007