Membranes and Membrane Transport

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What is a membrane composed of?
Phospholipid Bilayer
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what is the typical thickness of a membrane?
5nm
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what are Fatty acids composed of?
Long hydrocarbon chain + carboxyl end and methyl end
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what are fatty acids commonly attached too and how?
Glycerol via covalent ester linkage (Tryglyceride/tryacyglycerol)
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what is a unsaturated fatty acid?
Contains a double bond between two carbons
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what is the structure of a Phospholipid?
2x fatty acids attached to glycerol, glycerol attached to phosphate group with (choline, amine or serine)
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What is polarity?
How equal two atoms share electrons(non-equal = polar)
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what part of a phospholipid is polar?
The head (Phosphate)
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what part of a phospholipid is non-polar?
the tail (fatty acid)
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why do polar molecules dissolve in water?
Because dissolving makes it energetically favourable
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what is the name given to a molecule which is both hydrophobic and hydrophilic?
Amphipathic
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how does formation of lipid bilayer occur?
in order to prevent hydrophobic fatty acids from being in contact with water, lipid bilayer will for spheroid shape
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the fluidity of a membrane is directly linked to what?
the viscosity of the membrane
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in what direction can phospholipid move?
Laterally
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How do phospholipid move from one layer to the other?
via transporter proteins (translocase)
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what are the two regulators for membrane fluidity?
Cis double bonds and cholesterol
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How is a Cis double bond formed
Double bond between two carbons, with both hydrogen atoms on one side (creates kink)
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How does the Cis double bond effect fluidity of membrane
Prevents phospholipids from being tightly packed, decreases width of membrane
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what is the basic structure of cholesterol
Steroid ring with hydrophilic head
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how does cholesterol effect fluidity of membrane
Hydrophilic(polar) head binds to hydrophilic region of phospholipid, steroid ring is rigid = prevent compaction
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what are phospholipids without cis double bond called?
Sphingolipids
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what do sphingolipids form?
Lipid rifts in membrane
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What are usually located in lipid rifts?
Transporter proteins (transmembrane)
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what do glycoproteins and glycolipids form around a membrane
Glycocaylx
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what side of the membrane is the glycocaylx found?
Non-cytoplasmic side
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what are the TWO types of membrane protein formations
B-barrels/sheets and a-helices
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what are the TWO types of transmembrane protein passes
Single pass(Span membrane once) + Multi pass (Span membrane more than once)
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what are membranes that don't span across the entire membrane called?
Peripheral proteins
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what type of transmembrane protein usually forms channels across membrane
B-sheet transmembrane proteins
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what method of transport would a non-polar molecule undergo to cross a membrane
simple diffusion along its concentration gradient
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what method of transport would a small, non-charged but polar molecule undergo?
diffusion but would be slower
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what method of transport would a large, non-charged but polar molecule undergo?
Most likely will need a transporter
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what method of transport would a ion undergo to cross membrane
specialised mechanism
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what method of transport would a large, charged and polar molecule undergo
very specialised transport mechanism
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what type of protein are transporter proteins?
transmembrane multipass
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what are the two types of transporter proteins
Carrier proteins & Channel proteins
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what type of transport does both carrier and channel proteins enable
Facilitated Diffusion
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What is facilitated diffusion?
Transport of molecules along its concentration gradient across a transported protein
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what gradient do ions travel along?
Electrochemical gradient (charge and chemical concentrations)
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what type of transport do carrier proteins undergo but channel proteins don't?
Active transport
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What is Active Transport?
Transport of molecule against its concentration/electrochemical gradient with the use of energy
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what are the two main mechanisms active transport is carrier out by?
Coupled carriers & ATPase pumps
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Where is the energy from used by coupled carriers
From the electrochemical gradient of a molecule
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what are the TWO types of coupled carriers?
Symporters & antiporters
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what are symporters?
co-transport of two molecules in the same direction, one against electrochemical gradient the other along
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give a example of a symporter?
Sodium-glucose symporter
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give a example of a antiporter?
Malate-Aspartate shuttle
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Card 2

Front

what is the typical thickness of a membrane?

Back

5nm

Card 3

Front

what are Fatty acids composed of?

Back

Preview of the front of card 3

Card 4

Front

what are fatty acids commonly attached too and how?

Back

Preview of the front of card 4

Card 5

Front

what is a unsaturated fatty acid?

Back

Preview of the front of card 5
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