Download 3.3 Cell Membrane (p. 81) 3.4 Diffusion and Osmosis

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Bio PreAP/GT
3.3 Cell Membrane (p. 81)
Cell Membranes are composed of two phospholipid layers.
The cell membrane, or the _____________ membrane, forms a boundary between a cell and the
outside environment and controls the passage of materials into and out of the cell.
• A phospholipid molecule has three parts:
o Head composed of ____________ __________ and _____________
 Charged [polar]
 ________________ - forms _______________ bonds with water
o 2 ____________ ___________ tails
 Nonpolar
 ________________ – attracted to each other and repelled by water
o Arranged as a ______________
 polar _________________ on the outside
 nonpolar ______________ in the middle
• Sketch figure 3.1 in the space provided. Label, proteins, protein channel, phospholipid,
cholesterol and carbohydrate chain
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•
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Embedded in the plasma membrane are cell surface ____________ that allow
larger materials to pass into and out of the cell.
o These proteins are called _____________.
________ _________ _______ describes arrangement of molecules in membrane.
o Flexible; not rigid
o Membrane behaves as a fluid
______________ ________________ - membrane allows some, but not all,
materials to cross.
Chemical signals are transmitted across the cell membrane.
• _____________ – protein that detects a signal molecule and performs
an action in response.
o Recognizes and binds to only certain molecules – ligand.
o Causes them to change shape.
• _____________ receptor – within the cell
• _____________ receptor –located in the cell membrane
3.4 Diffusion and Osmosis
Diffusion and osmosis are types of passive transport.
• ________________ transport – movement of molecules across a cell membrane
_________________ energy input from the cell
o _____________________ - movement of molecules in a fluid or
gas from a region of higher concentration to a region of lower
concentration.
 It take place wherever there is a difference in __________________
within the solution.
 __________________ _______________ - difference in concentration
 Particles of a solute and solvent are constantly moving from areas
of _______ concentration to areas of ___________ concentration.
 These particles continue to move until the concentrations are equal or reach . . .
______________________.
o ____________________ - diffusion of water molecules
from high to low across a semipermeable membrane
 If a solution has a higher concentration
of dissolved particles, then it will have a
_________concentration of water molecules in
the same solution
 the increased pressure that results from an
increase of water is called ______________
___________________
Refer to the figures below to answer the following questions.
1.
2.
3.
4.
5.
6.
concentration of sucrose is higher in compartment ?
concentration of water is higher in compartment ?
osmosis occurs with movement from _?_ into _?_
diffusion of sucrose will/will not occur.
level of column A will increase/ decrease/ remain the same.
level of column B will increase/ decrease/ remain the same.
*A column of fluid develops which creates a pressure that prevents the solution from increasing its
volume further. Osmotic pressure has the effect of pushing water molecules of compartment A back
into B. At this point, the number of water molecules moving in and out of compartment A is equal,
so _______________________ exists.
A. The cell solution is said to be ____________________
when there is a ______________ concentration of
solute in the environment than that in the cell. Thus,
the environment solution is said to be ____________.
Water will move _______________ the cell. This is the
shrinking of the cell due to water leaving the cell. . .
_______________________________.
B. The cell solution is said to be ____________________
when there is a _______________ concentration of
solute in the environment than that in the cell. Thus,
the environment solution is said to be _____________.
Water will move ___________ the cell. This is the bursting
of the cell due to water entering the cell. . .
______________________________.
C. A cell is said to be _________________ when the
concentration of solutes in the environment and in the
cell are the _________________. Equal amounts of water
will move _____________ and _________________ the cell.
o Do you understand Osmosis?
Cell (compared to beaker) hypertonic or hypotonic
Beaker (compared to cell)  hypertonic or hypotonic
Which way does the water flow?  in or out of cell
o ________________ _________________ - diffusion of molecules
across a membrane through transport proteins.
Examples:
Flasks X, Y, and Z contain solutions with different concentrations of the solute NaCl. Flask X has
0.5% NaCl, Y has 0.9% NaCl, and Z has 1.5% NaCl. Red blood cells (0.9% NaCl) will be placed in
each flask.
Flask X _____% of NaCl in flask
_____% of water in flask
_____% of NaCl in red blood cells
_____% of water in red blood cells
The environment solution is _______ and the cell solution is __________ , therefore
water will move ______ the cell.
Flask Y _____% of NaCl in flask
_____% of water in flask
_____% of NaCl in red blood cells
_____% of water in red blood cells
The environment solution is _______ and the cell solution is __________ , therefore
water will move ________ the cell.
Flask Z _____% of NaCl in flask
_____% of water in flask
_____% of NaCl in red blood cells
_____% of water in red blood cells
The environment solution is _______ and the cell solution is __________ , therefore
water will move _____ the cell.
3.5 Active Transport, Endocytosis, and Exocytosis
Proteins can transport materials against a concentration gradient.
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Cells must have a way to maintain concentrations of important
food molecules at a level different from the concentration level
outside the cell.
Active transport uses __________ to transport particles through a
membrane _________ the concentration gradient. An example of an
active transport channel is the _____________-______________ pump.
____________ is required.
o ___________________ is the taking in of particles into a cell by engulfing them in a
membrane.
o Two types:
 _________________________ is the taking in of liquid or dissolved materials.
 _________________________ is the taking in of large solid materials.
o ____________________ is the removal of wastes out of a cell by the fusion of a vesicle with
the membrane