Cell membranesCell membranesLinks to GCSELinks to GCSEStructure of animals & plant cellsStructure of animals & plant cellsDiffusionDiffusionSensitivitySensitivityHormonesHormones

• State that plasma (cell surface) membranes are State that plasma (cell surface) membranes are partially permeable barriers.partially permeable barriers.

• Outline the roles of membranes within cells and at the Outline the roles of membranes within cells and at the surface of cells.surface of cells.

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Week 3

Membranes play a role Membranes play a role in:in:

Separating cell contents from the external Separating cell contents from the external environmentenvironment

Separating cell components from cytoplasmSeparating cell components from cytoplasm Cell recognition & signallingCell recognition & signalling Holding the components of some metabolic Holding the components of some metabolic

pathways in placepathways in place Regulating the transport of materials into & Regulating the transport of materials into &

out of cellsout of cells

PhospholipidsPhospholipidsA)A) Phospholipid molecule enlarged Phospholipid molecule enlarged

B)B) Layer of phospholipids at the surface of waterLayer of phospholipids at the surface of water

A phospholipid bilayerA phospholipid bilayer

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Week 3

Through an electron Through an electron microscope 7-10nmmicroscope 7-10nm

• Describe the fluid mosaic model of membrane structure.Describe the fluid mosaic model of membrane structure.

• Describe the roles of the components of the cell membrane, Describe the roles of the components of the cell membrane, including phospholipids, cholesterol, glycolipids, proteins and including phospholipids, cholesterol, glycolipids, proteins and glycoproteins.glycoproteins.

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Week 3

The ‘Fluid Mosaic Model’ of The ‘Fluid Mosaic Model’ of cell membranes, Singer & cell membranes, Singer &

Nicholson Nicholson

Making a model of the Making a model of the ‘Fluid Mosaic Model’!‘Fluid Mosaic Model’!

You will be provided with a range of materials You will be provided with a range of materials to help you construct a large physical model of to help you construct a large physical model of ‘The Fluid Mosaic Model of Membranes’‘The Fluid Mosaic Model of Membranes’

Your model should contain the key structures Your model should contain the key structures present in a cell membranepresent in a cell membrane

You will be expected to present your model You will be expected to present your model and explain the functions of ALL of the key and explain the functions of ALL of the key structures structures

You have the remainder of this lesson and only You have the remainder of this lesson and only one more for preparation, so will have to work one more for preparation, so will have to work on this outside of lessons (i.e. HOMEWORK!!)on this outside of lessons (i.e. HOMEWORK!!)

• Outline the effects of changing temperature on Outline the effects of changing temperature on membrane structure and permeability.membrane structure and permeability.

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Week 3

• Explain the term ‘cell signalling’.Explain the term ‘cell signalling’.

• Explain the role of membrane-bound receptors as sites Explain the role of membrane-bound receptors as sites where hormones and drugs can bind.where hormones and drugs can bind.

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Week 3

Key definitionsKey definitions

Cell signalling: cells communicate with Cell signalling: cells communicate with one another by signals. Many molecules one another by signals. Many molecules act as signals –some signal during act as signals –some signal during processes taking place inside cells; processes taking place inside cells; others signal from one cell to others. others signal from one cell to others. Cytokines are an example of cell signals.Cytokines are an example of cell signals.

Chemicals & receptor Chemicals & receptor effectseffects

InsulinInsulin Medical drugs such as anti histamines/ Medical drugs such as anti histamines/

beta blockers (high blood pressure), beta blockers (high blood pressure),

L dopa (schizophrenia) etcL dopa (schizophrenia) etc Botox (botulism toxin!)Botox (botulism toxin!) HIV entry into cellsHIV entry into cells

Membrane transportMembrane transport

Links to GCSELinks to GCSE DiffusionDiffusion OsmosisOsmosis

• Describe and explain what is meant by passive Describe and explain what is meant by passive transport (diffusion and facilitated diffusion).transport (diffusion and facilitated diffusion).

• Describe the role of membrane proteins in passive Describe the role of membrane proteins in passive transport.transport.

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Week 4

(a) Simple diffusion(a) Simple diffusion

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Week 4

(b) Facilitated diffusion using a (b) Facilitated diffusion using a

channel proteinchannel protein

((c) Facilitated diffusion using a c) Facilitated diffusion using a

carrier proteincarrier protein

Key termsKey terms DIFFUSION: the movement of molecules DIFFUSION: the movement of molecules

from a region of high concentration to a from a region of high concentration to a region of lower concentration (of that region of lower concentration (of that molecule) down a concentration gradient.molecule) down a concentration gradient.

KINETIC ENERGY: movement energy KINETIC ENERGY: movement energy possessed by molecules.possessed by molecules.

EQUILIBRIUM: no OVERALL movement EQUILIBRIUM: no OVERALL movement of moleculesof molecules

• Describe and explain what is meant by active transport.Describe and explain what is meant by active transport.

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Week 4

• Describe and explain what is meant by endocytosis Describe and explain what is meant by endocytosis and exocytosis.and exocytosis.

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Week 4

• Explain what is meant by osmosis, in terms of water Explain what is meant by osmosis, in terms of water potential.potential.

• Recognise and explain the effects of solutions of Recognise and explain the effects of solutions of different water potentials on plant and animal cells.different water potentials on plant and animal cells.

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Week 4

Osmosis and membraneOsmosis and membrane

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Week 4

Plant and animal cells in solutions of high water potential - before and afterPlant and animal cells in solutions of high water potential - before and after

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Week 4

Plant and animal cells in solutions of low water potential - before and afterPlant and animal cells in solutions of low water potential - before and after

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Week 4

• State that plasma (cell surface) membranes are partially permeable State that plasma (cell surface) membranes are partially permeable barriers.barriers.

• Outline the roles of membranes within cells and at the surface of cells.Outline the roles of membranes within cells and at the surface of cells.• Describe the fluid mosaic model of membrane structure.Describe the fluid mosaic model of membrane structure.• Describe the roles of the components of the cell membrane, including Describe the roles of the components of the cell membrane, including

phospholipids, cholesterol, glycolipids, proteins and glycoproteins.phospholipids, cholesterol, glycolipids, proteins and glycoproteins.• Outline the effects of changing temperature on membrane structure and Outline the effects of changing temperature on membrane structure and

permeability.permeability.• Explain the term ‘cell signalling’.Explain the term ‘cell signalling’.• Explain the role of membrane-bound receptors as sites where hormones Explain the role of membrane-bound receptors as sites where hormones

and drugs can bind.and drugs can bind.• Describe and explain what is meant by passive transport (diffusion and Describe and explain what is meant by passive transport (diffusion and

facilitated diffusion).facilitated diffusion).• Describe the role of membrane proteins in passive transport.Describe the role of membrane proteins in passive transport.• Explain what is meant by osmosis, in terms of water potential.Explain what is meant by osmosis, in terms of water potential.• Recognise and explain the effects of solutions of different water potentials Recognise and explain the effects of solutions of different water potentials

on plant and animal cells.on plant and animal cells.