Transcript Cell membranes - the Redhill Academy

Cell membranes
Links to GCSE
Structure of animals & plant cells
Diffusion
Sensitivity
Hormones
Week 3
• State that plasma (cell surface) membranes are
partially permeable barriers.
• Outline the roles of membranes within cells and at the
surface of cells.
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Membranes play a role in:
 Separating cell contents from the external
environment
 Separating cell components from cytoplasm
 Cell recognition & signalling
 Holding the components of some metabolic
pathways in place
 Regulating the transport of materials into &
out of cells
Phospholipids
A) Phospholipid molecule enlarged
B) Layer of phospholipids at the surface of water
Week 3
A phospholipid bilayer
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Through an electron
microscope 7-10nm
Week 3
• Describe the fluid mosaic model of membrane structure.
• Describe the roles of the components of the cell membrane,
including phospholipids, cholesterol, glycolipids, proteins and
glycoproteins.
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The ‘Fluid Mosaic Model’ of
cell membranes, Singer &
Nicholson
Making a model of the
‘Fluid Mosaic Model’!
 You will be provided with a range of materials
to help you construct a large physical model of
‘The Fluid Mosaic Model of Membranes’
 Your model should contain the key structures
present in a cell membrane
 You will be expected to present your model and
explain the functions of ALL of the key
structures
 You have the remainder of this lesson and only
one more for preparation, so will have to work
on this outside of lessons (i.e. HOMEWORK!!)
Week 3
• Outline the effects of changing temperature on
membrane structure and permeability.
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Week 3
• Explain the term ‘cell signalling’.
• Explain the role of membrane-bound receptors as sites
where hormones and drugs can bind.
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Key definitions
 Cell signalling: cells communicate with
one another by signals. Many molecules
act as signals –some signal during
processes taking place inside cells;
others signal from one cell to others.
Cytokines are an example of cell signals.
Chemicals & receptor
effects
 Insulin
 Medical drugs such as anti histamines/
beta blockers (high blood pressure),
L dopa (schizophrenia) etc
 Botox (botulism toxin!)
 HIV entry into cells
Membrane transport
 Links to GCSE
 Diffusion
 Osmosis
Week 4
• Describe and explain what is meant by passive
transport (diffusion and facilitated diffusion).
• Describe the role of membrane proteins in passive
transport.
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Week 4
(a) Simple diffusion
(b) Facilitated diffusion using a
channel protein
(c) Facilitated diffusion using a
carrier protein
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Key terms
 DIFFUSION: the movement of molecules
from a region of high concentration to a
region of lower concentration (of that
molecule) down a concentration gradient.
 KINETIC ENERGY: movement energy
possessed by molecules.
 EQUILIBRIUM: no OVERALL movement
of molecules
Week 4
• Describe and explain what is meant by active transport.
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Week 4
• Describe and explain what is meant by endocytosis
and exocytosis.
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Week 4
• Explain what is meant by osmosis, in terms of water
potential.
• Recognise and explain the effects of solutions of
different water potentials on plant and animal cells.
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Week 4
Osmosis and membrane
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Week 4
Plant 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 after
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• State that plasma (cell surface) membranes are partially permeable
barriers.
• Outline the roles of membranes within cells and at the surface of cells.
• Describe the fluid mosaic model of membrane structure.
• Describe the roles of the components of the cell membrane, including
phospholipids, cholesterol, glycolipids, proteins and glycoproteins.
• Outline the effects of changing temperature on membrane structure and
permeability.
• Explain the term ‘cell signalling’.
• Explain the role of membrane-bound receptors as sites where hormones
and drugs can bind.
• Describe and explain what is meant by passive transport (diffusion and
facilitated diffusion).
• Describe the role of membrane proteins in passive transport.
• Explain what is meant by osmosis, in terms of water potential.
• Recognise and explain the effects of solutions of different water potentials
on plant and animal cells.