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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

Regulates movement of substances in / out of cell (selectively permeable)

Transport

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FUNCTIONS OF PLASMA MEMBRANE

Allows cells to identify surrounding cells

Cell recognition

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 Transductionconverts a mechanical/chemical stimulus to a cell into a specific cellular response.

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FUNCTIONS OF PLASMA MEMBRANE

Enzyme ActivityCells 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

Proteins (intergral & peripheral)Carbohydrates (glucose)

PhospholipidsCholesterol

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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 PROTEINSProteins which

attach to the membrane

Predominately interact with integral proteins

Can attach by weak hydrogen bonds

1. interaction by 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)

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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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GLYCOLIPIDSBetween 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-mosaic-model.html

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References

Original presentation by M.Bregar (Dante C.S.S.) http://www.authorstream.com/Presentation/aSGuest77986-711145-fluid-mosaic-model/

Modified by D. Machacek