Cellular Transport and the Cell Cycle

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CHAPTER 8 Cellular Transport and the Cell Cycle
Review Vocabulary plasma membrane the boundary
between the cell and its environment.
www.mybiology.com/.../ the_cell_movies.htm
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8.1 Cellular Transport Osmosis Diffusion of
Water In a cell, water always moves to reach
equilibrium on both sides (inside and out) of the
cell membrane. The diffusion of water from an
area of higher concentration to area of lower
concentration (as compared to the other molecules
within the water) is known as osmosis.
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Types of Solutions 1. isotonic solution 2.
hypotonic solution 3. hypertonic solution
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1. isotonic solutions from the Greek word iso
meaning equal contain the same concentration
of solute as an another solution (e.g. the cell's
cytoplasm). When a cell is placed in an isotonic
solution, the water diffuses into and out of the
cell at the same rate. The fluid that surrounds
the body cells is isotonic.
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If the solution is isotonic relative to the cell,
then the solute concentrations are the same on
both sides of the membrane and water moves
equally in both directions
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2. hypotonic solutions - from the Greek word
hypo meaning under contain a low
concentration of solute relative to another
solution (e.g. the cell's cytoplasm). When a cell
is placed in a hypotonic solution, the water
diffuses into the cell, causing the cell to swell
and possibly explode.
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A hypotonic solution has decreased solute
concentration, and a net movement of water inside
the cell, causing swelling or breakage.
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3. hypertonic solution - from the Greek word
hyper meaning under contain a high
concentration of solute relative to another
solution (e.g. the cell's cytoplasm). When a cell
is placed in a hypertonic solution, the water
diffuses out of the cell, causing the cell to
shrivel.
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A hypertonic solution has increased solute, and a
net movement of water outside causing the cell to
shrink.
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Passive Transport - the movement of particles
across a membrane without the use of energy. Two
Types 1. simple diffusion 2. facilitated
diffusion Both of these types diffuse WITH the
concentration gradient.
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Simple Diffusion - no transport protein used -
moves with concentration gradient - requires no
energy input from the cell
www.mybiology.com/.../ the_cell_movies.htm
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Facilitated Diffusion - channel or carrier
protein used - moves with the concentration
gradient - requires no energy input from the cell
www.mybiology.com/.../ the_cell_movies.htm
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Active Transport - the movement of materials
across a membrane, against the concentration
gradient, REQUIRING the use of energy. -
requires carrier protein - moves against the
concentration gradient - REQUIRES ENERGY
input from the cell watch the following clips
and summarize the steps involved use your text
pg 199 if needed
www.mybiology.com/.../ the_cell_movies.htm
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On a test, you should be able to look at a
diagram, similar to the following diagram, and be
able to compare and contrast the different types
of transport
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Transport of Large Particles aka, Bulk
Packaging Some molecules are WAY too large for
the previously mentioned transport methods. For
example, some unicellular organisms will ingest
entire cells! WOW!!! When this is the case,
endocytosis and exocytosis are the preferred
method of (bulk) transport. This comes with a
price ENERGY USE!!!
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Endocytosis is a process by which a cell
surrounds and takes in material from its
environment. The basic steps are as follows
1. engulf 2. enclose 3. vacuole formation
The reverse of this process is known as
exocytosis removes wastes home.earthlink.net/
shalpine/anim/