Download fluid mosaic model

FLUID MOSAIC MODEL
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FLUID MOSAIC MODEL
 Model describing
structure of the cell
membrane
 Model says cell
membrane is not solid,
fluid.
 Has the consistency of
olive oil
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FUNCTIONS OF PLASMA MEMBRANE
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FUNCTIONS OF PLASMA MEMBRANE
 Protective barrier - contains cytoplasm (contents of the cell)
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FUNCTIONS OF PLASMA MEMBRANE
Transport
Regulates movement of substances in / out of cell (selectively permeable)
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FUNCTIONS OF PLASMA MEMBRANE
Cell recognition
Allows cells to identify surrounding cells
http://www.dailymail.co.uk/sciencetech/article-491062/Multicoloured-brainbow-shows-nerve-activity.html
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FUNCTIONS OF PLASMA MEMBRANE
Cellular Attachment
Cell membranes have junctions – surfaces which interlock keeps cells
together – and surfaces which attach them to the extra cellular matrix.
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FUNCTIONS OF PLASMA MEMBRANE
Signal Transduction
converts a mechanical/chemical stimulus to a cell into a specific cellular
response.
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FUNCTIONS OF PLASMA MEMBRANE
Enzyme Activity
Cells rely on thousands of different enzymes to catalyze metabolic reactions,
many of these occur at the cell membrane.
http://www.nature.com/scitable/topicpage/protein-function-14123348
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STRUCTURE OF PLASMA MEMBRANE
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MEMBRANE COMPONENTS
 Phospholipids
 Proteins (intergral & peripheral)
 Cholesterol
 Carbohydrates (glucose)
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PHOSPHOLIPIDS
 Make up 30-70% of the
cell membrane
 Phospholipids are like
triglycerides with a
phosphate
 Come together to make a
fluid membrane
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PHOSPHOLIPID ORIENTATION
 In water,
phospholipids
form a bilayer
 A cell membrane
is a bilayer
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PHOSPHOLIPID ORIENTATION
 Liposome is a small
vesicle, with an
aqueous compartment
surrounded by a bilayer
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PHOSPHOLIPID ORIENTATION
PHOSPHATE HEADS –
are water loving and point
toward water
FATTY ACID TAILS – are
water fearing and orient
themselves to each other
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PHOSPHATE HEAD – HYDROPHYLIC
FATTY ACID TAILS – HYDROPHOBIC
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CLOSER LOOK OF THE PLASMA
MEMBRANE
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PROTEINS
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INTEGRAL PROTEINS
 Proteins
surrounded by
phospholipids
which go through
the membrane
 Functions: serve
as ion channels,
membrane pumps,
or receptors
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FLUID MOSAIC MODEL
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INTEGRAL PROTEINS
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PERIPHERAL PROTEINS
 Proteins which
attach to the
membrane
 Predominately
interact with
integral proteins
an amphipathic α-helix parallel to the membrane plane
(in-plane membrane helix) 2. interaction by a hydrophobic loop 3.
interaction by a covalently bound membrane lipid (lipidation) 4.
electrostatic or ionic interactions with membrane lipids (e.g.through a
calcium ion)
1. interaction by
 Can attach by
weak hydrogen
bonds
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PERIPHERAL PROTEINS
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GLYCOPROTEINS
 GLYCOPROTEINS
found on the surface
of the membrane
 Serve as recognition
sites for chemicals
 Involved in cell to cell
interactions
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GLYCOLIPIDS
 Between phospholipids
 Face extracellular fluid and serve as “cell identifiers”
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CHOLESTEROL
 Involved in keeping
membrane “fluid”
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GLYCOLIPIDS
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REVIEW
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http://bio-animations.blogspot.ca/2008/04/plasma-membrance-fluid-mosaicmodel.html
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References
 Original presentation by M.Bregar (Dante C.S.S.)
http://www.authorstream.com/Presentation/aSGue
st77986-711145-fluid-mosaic-model/
 Modified by D. Machacek
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