Cellular communication

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  • Created by: Alex
  • Created on: 26-05-13 15:29
What is the plasma membrane?
The outer barrier of all eukaryotic cells
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What is the plasma membrane made of
A phospholipid bilayer - thin layer of proteins and lipis
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Function of the plasma membrane
Maintains the difference in fluid composition between the intracellular and extracellular parts of a cell
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Phospholipid bilayer is made of amphiphilic molecules. what does this mean>
polar hydrophilic water-soluble head (glycerol molecule) attatched to a hydrophobic non-polar water-insoluble tail. (2f atty acids chains)
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4 major phospholipids
Phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine & sphingomyelin.
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which of major 4 phospholipids is important in cell signalling?
phosphatidylinositol
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what % do lipid molecules make up of most animal cell membranes? and what is most of the rest
50% the rest is mainly protein
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What are the major classes of lipid?
Phospholipids, cholesterol and glycolipids
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What is the function of cholesterol in the lipid bilayer?
contributes to fluidity-(stops packing together and crystallising-restricts wan der walls) and stability of the membrane (counter some temperture induced changes in fluidity) Interacts strongly with Hydrocarbon chain near head to stop region moving
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What make up of saturates and unsaturated fatty acids is best for cold temperatures?
High polyunsaturated fatty acids (PUFA) low saturated fatty acids (SFA) the double bonds (points of unsaturated ness) don't become too rigid in the col
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What make up of saturates and unsaturated fatty acids is best for hot temperatures?
High SFA, low PUFA
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What is the role of the plasma membrane?
regulate the passage of materials, divide cells into compartments, surface for chemical reactions, adhere to and to communicate with cells, transmit signals between environment and interior of cell
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Types of communication between cells.
Via gap junctions, signaling molecules on the surface of cells, chemical messengers
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Communication via diffusion
Some signals pass through the plasma membrane unaided. e.g. steroid hormones and nitric oxide
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Function of nitric oxide
Relaxes small blood vessels-controls blood flow through tissue - maintains arteriol pressure. chemical warfare agent against bacteria & cancer cells by macrophages. Neurotransmitter - synthesised by neuron terminal& diffuses out to the target cell.
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What is a receptor and why are they necessary
Some signals need help to travel across the membrane. they bind to proteins called receptor which carry the signal across it
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Stages of Signalling using receptor proteins
Extra cellular signal molecule -> Receptor protein on membrane -> intracellular signalling proteins -> effector proteins -> altered gene expression/metabolism/shape/movement
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Different types of membrane proteins
Channels, carriers, receptors, docking-marker acceptors, enzymes, cell adhesion molwcules and self-identifying markers
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Function of channel proteins
enable water-soluble ions of specific size and kind to pass through the membrane. some can open and close = gated
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Function of carrier proteins
transport specific substances across the membrane - span entire membrane
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Function of receptor proteins
recognise and bind specific molecules in the extracellular environment - binding initiates a series of events within the membrane and in the intracellular environment
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Function of docking-marker acceptor proteins
bind lock-and-key fashion with vesicles
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Function of enzymes
Control specific reactions at either the inner or outer cell surface
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Function of cell adhesion molecules (CAMs)
Protrude and hold cells together. some span the membrane and link the external environment with intracellular components
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Forms of intracellular communication
Contact-dependent, paracrine, synaptic and endocrine
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Whats contact dependent communication
membrane bound signaling molecule on the signalling cell touches receptor on target cell. Gap junctions make most rapid communication. works in both directions. important during development
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Whats paracrine communication
when a signal cell releases a local mediator that binds to a receptor on the target. target cell depends on paracrine released. clear quickly from local environment
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Whats synaptic communication
Neuronal with neurons, neurotransmitters, synapses and target cells.
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Whats endocrine communication
the release of hormones into the blood stream. communicate over long distances. slow communication
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Whats a paracrine
Local chemical messenger that act on cells in the immediate environment
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whats an autocrine
messenger that acts on the same cell type
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why is neurotransmitter released?
in response to electrical signals
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Other cards in this set

Card 2

Front

What is the plasma membrane made of

Back

A phospholipid bilayer - thin layer of proteins and lipis

Card 3

Front

Function of the plasma membrane

Back

Preview of the front of card 3

Card 4

Front

Phospholipid bilayer is made of amphiphilic molecules. what does this mean>

Back

Preview of the front of card 4

Card 5

Front

4 major phospholipids

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