Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a...

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Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages

Transcript of Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a...

Page 1: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

Membranes

Cell membrane = Plasmalemma = Plasma membrane

Surrounds cells and most organelles

Forms a network of passages

Page 2: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

Mitochondria, chloroplasts, and the nucleus all have a double membrane

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Functions of plasmalemma

1. Keep cell contents together and separate from other cells

2. Controls movement of substances into and out of cells

3. Allow communication between cells

4. Attachment for intracellular cytoskeleton, cell walls and intercellular adhesions

Page 4: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

Membranes are made of Phospholipids

Hydrophilic Polar head

Hydrophobic Non-polar tails

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Hydrophobic tails

Hydrophilic heads

Watery cytosol

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Water outside cell

Hydrophobic tails

Watery Cytoplasm

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Fluid mosaic theory

• Phospholipids are not bound to each other

• Like oil on water

• Water inside and outside the cell

http://www.youtube.com/watch?v=ULR79TiUj80&feature=related

(fluid mosaic model, 1.5 min)

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Permeability

Membranes are selectively permeable

Allow some molecules through but not all

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Permeability of membrane

Some membranes impermeable (eg surfaces designed to retain water such as skin, scales, exoskeletons)

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MENU

Key Words

Exercises

Quick Quiz

Videos

Extra slides

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Key wordsPhospholipidsBilayerFatty tailsPhosphate headImpermeablePermeableLarge moleculesIonsFluid Mosaic

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Page 14: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

(VERY) Quick quiz1. ____ are the main component of membranes 2. They consist of hydrophobic ____3. And a hydrophilic ____4. They also have integral and peripheral ____

Answers

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Page 15: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

(VERY) Quick quiz1. Phospholipids are the main component of

membranes

2. They consist of hydrophobic tails3. And a hydrophilic head4. They also have integral and peripheral proteins

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Page 16: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

Exercise

Workbook pp50-52, qq18-20 and 22-23Booklet p3

READING• Pathfinder p48 (or p42) Enzymes & reaction

rate• Excellence in Biology pp114-6

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Page 17: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

Videos

http://www.youtube.com/watch?v=E90D4BmaVJM&feature=related

(10 min, includes biotechnology)http://www.teachersdomain.org/asset/tdc02_int_membraneweb/

(interactive - membrane)

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Page 18: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

Glycoproteins & glycolipids for cell recognitionhttp://www.5min.com/Video/Proteins-as-the-Mosaic-of-the-Cell-Membrane-150624158 Back to

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Peripheral proteins

Partially embedded intrinsic – inside cell extrinsic – outside cell

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Page 20: Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages.

OIL AND WATER

I told you this would be important!

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Trans-membrane (integral) proteins

• involved in facilitated and active transport

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