Download membrane model

BIOLOGY - Activity
Membrane Model
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Period 1 2 3 4 5 6 7 8
Date : _______________
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INTRODUCTION
Cell membranes are made of a double layer of phospholipid molecules called a bilayer with the phosphate
heads projecting outwards on both sides and the lipid tails on the inside. Embedded in this bilayer structure are
various proteins, some of which extend completely through the membrane. Some of these proteins may act as
channels or conduits to aid different molecules in passing in or out of the cell while others may be involved with cell
identification and communication. This is illustrated in the diagram below.
OBJECTIVE
To construct a model of a small section of cell membrane to help visualize the bilayer structure with its
attendant proteins.
MATERIALS
Scissors
tape
diagrams to cut out
PROCEDURE
1.
Cut out the phospholipid bilayer along the solid lines. Cut all the way to the edges of the paper
in the direction of the arrows.
2.
Fold the cut out along the dotted lines and tape the edges together to form a fully enclosed
rectangular box.
3.
Cut out the 5 protein models along the solid black lines and fold on the dotted lines
4.
Form 3-D shapes with the proteins by joining the sides and tops together and taping in place.
Use the tabs to help.
5.
Tape the 3-D shapes into place at random spots along both edges of the phospholipid bilayer.
The completed model should be able to stand on its protein “legs”. See diagram below
ANALYSIS
1.
Why is the cell membrane described as being a bilayer?
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2.
What is a phospholipid?
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3.
What is the function of the cell membrane?
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4.
Name three types of proteins embedded in the cell membrane and explain their function.
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5.
Why do cells need energy to move some substances across the membrane?
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6.
Why do scientists describe the cell membrane model as a fluid mosaic?
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