Download Cell Membranes

Cell Membrane Structure
BUBBLES!!
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MUST wear goggles at ALL times!
NO taking straw out of the dish!
NO drinking/ inhaling bubble fluid
THIS IS an EXPERIMENT!!!
You can have fun, but ALL usual lab
safety RULES APPLY!
Questions to think about:
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Can anything pass through the bubble
without breaking it?
Can one bubble divide to become several
bubbles?
Can several bubbles merge to form onehow?
Can a drop of water pass through a
bubble without popping it?
Does it look like the surface of the bubble
moves? How can you tell?
Bubble Summary!
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A bubble is a lipid monolayer!!
How does a bubble model the fluid
nature of a cell membrane?
What is the structure of the
membranes of our cells?
Key words to know!
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Hydrophilic
Hydrophobic
Cell Membrane
Fluid Mosaic Model
Phospholipid
Cholesterol
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Diffusion
Osmosis
Selectively
Permeable
Passive Transport
Active Transport
AS Biology. Foundation. Cell membranes and
Transport
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1.
Learning Objectives
Describe the fluid mosaic model of membrane
structure and explain the reasons for its
structure.
2.
Outline the roles of phospholipids, cholesterol,
glycolipids, proteins and glycoproteins in
membranes.
3.
Outline the roles of the plasma membrane,
and the roles of membranes within cells.
Cell Membranes
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AKA Plasma membrane
What are the functions of the cell
membrane?
How does its structure allow it to carry
out its functions?
Cell (plasma) Membrane
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Encloses the cell’s contents
Selectively Permiableregulates which particles
(nutrients, wastes) can
enter and exit the cell.
Cell communication
recognition
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Transport
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Cell Membranes:
Every cell is enclosed by a double
layer of phospholipids.
Cell Membrane Structure
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Building blocks are phospholipids…
– Lipid with a phosphate group in place of one fatty
acid chain.
– Phosphate head is hydrophilic, fatty acid tail is
hydrophobic.
AS Biology. Foundation. Cell membranes and
Transport
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Phospholipids have Split
Personalities!
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HYDROPHOBIC tails (the fatty acid
portion)- HATE water!!
HYDROPHILIC heads (phosphate group)LOVE water!!
AS Biology. Foundation. Cell membranes and
Transport
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Phospholipid Bilayer
Properties of Cell
Membranes
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Phospholipids act as a barrier to most
water soluble substances... (“water
and oil don’t mix”)
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Transport
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What is a mosaic?
Fluid Mosaic Model
Phosopholipids, cholesterol and proteins form a
mosaic (pattern) within the cell membrane
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Transport
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Why call it a Fluid Mosaic
Model?
FLUID- phospholipids and some proteins
move around freely within the layer
MOSAIC- the pattern produced by
scattered protein molecules in the
membrane.
AS Biology. Foundation. Cell membranes and
Transport
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Visualizing structure and
function
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http://www.youtube.com/watch?v=Rl5
EmUQdkuI&feature=fvwp&NR=1&safe
=active
AS Biology. Foundation. Cell membranes and
Transport
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Functions of Proteins in Cell
Membrane
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Proteins act as channels for substances to move
in or out of cell.
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Some act as membrane enzymes in chemical
reactions.
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Glycoproteins act as receptors for cell
communication and recognition.
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Transport
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Function of Cholesterol In
Cell Membrane
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Cholesterol (a lipid) is found between
the phospholipid molecules in the cell
membrane.
Help maintain stability of the
membrane…not too fluid, not too rigid.
Functions of components of cell
membranes
Component
Description
Function
1. Phospholipids
2. Proteins
3. Cholesterol
AS Biology. Foundation. Cell membranes and
Transport
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