Membranes

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The most abundant lipids in most membranes are
Phospholipids
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Phospholipids have a glycerol backbone, two fatty acyl groups (tail) a phosphate group and _____
A head group
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Lipids contain hydrophobic and hydrophillic portions in their structure, this is known as __________
Amphipathic
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Micells can form given the right environment - this is where a polar head forms outside and __________
Hydrophobic tail inside
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Bilayer membranes are typically ____ nm thick
4-6
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The membrane is a fluid _________, made of proteins and lipids
Mosaic
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Membranes are primarily held together by ________
Hydrophobic interactions
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An aqueous environment enclosed by lipid bilayers is known as
Liposomes
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Lipid bilayers form _________
Spontaneously
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_________ form external boundaries of cells and separate compartments in cells
Membranes
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Some prokaryotes have double membranes, these are ________
Gram negative
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Gram positive bacteria have a _______ peptodoglycan cell wall
Thick
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Gram negative bacteria have a ______ peptidoglycan cell wall
Thin
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Lipids make up _____% of the cell membrane by mass
25-50
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Proteins make up ____% of the cell membrane by mass
50-75
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The fluid mosaic model was proposed by ________ in 1972
Singer and Nicholson
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Membrane proteins can undergo free ________ in a membranae
Free
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Lateral diffusion is movement _____________
Within a leafled
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The fluidity of a membrane depends on the composition in terms of
Acyl chains
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If membranes drop below the phase transition temperature they exist as
Gel
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If membranes rise above the phase transition temperature they exist as
Liquid
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Cholesterol is present in eukaryotic membranes at ______% by mass
20-25
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Cholesterol maintains fairly constant fluidity across temperature ranges by __________
Intercalating with acyl chains and disrupting ordered packaging
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Reigions enriched in sphingolipids and cholesterol are known as
Lipid rafts
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Cholesterol associates with sphingolipids due to their long _______ fatty acids
Saturated
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Movement of lipids between leaflets is known as
Transverse diffusion
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Transverse diffusion requires __________ than lateral diffusion
More energy
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Membranes are ________
Asymmetric
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Only one of the monolayers of the membrane is usually added to (inside), since transverse diffusion is slow this means
Lipids rarely flip between leaflets
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Asymmetry is __________ by flipases and flopases
Maintained
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SDS-PAGE is a type of electrophoresis that separates proteins according to their size, and can be used to analyse _____________
Membrane proteins
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_____________ proteins are bound mainly by electrostatics and hydrogen bonding to lipid head groups
Peripheral
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The distribution of membrane proteins can be seen by __________
Freeze fracture electron microscopy
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___________ are tethered to a membrane by a covalent bond to a lipid anchor
Lipid anchored membrane proteins
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Lipid anchored membrane proteins may also be linked to glycosylphosphatidylinositol, which is present only in the outer leaflet and found in _________
Lipid rafts
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___________ proteins are bound mainly by electrostatics and H bonding to lipid heads
Perioheral
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__________ proteins pass through the membrane
Integral
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The polar inteactions of ________ membrane proteins can be disrupted by NaCl
Peripheral
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_____________ membrane proteins associate with the hydrophobic acyl chains
Integral
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The structures of proteins in membranes can be alpha helices, beta barrels and
Loops
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The membrane proteins are not easy to work with because
They do not crystallise ealily
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Detergents can solubilise hydrophobic proteins, as they have
Hydrophobic and hydrophilic regions
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It can be shown that proteins move in a membrane by fluorescently tagging animal and human cell proteins, then _______ together and watch how they move
Fuse them together
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Limited diffusion creates a __________ membrane
Heterogenous
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Other cards in this set

Card 2

Front

Phospholipids have a glycerol backbone, two fatty acyl groups (tail) a phosphate group and _____

Back

A head group

Card 3

Front

Lipids contain hydrophobic and hydrophillic portions in their structure, this is known as __________

Back

Preview of the front of card 3

Card 4

Front

Micells can form given the right environment - this is where a polar head forms outside and __________

Back

Preview of the front of card 4

Card 5

Front

Bilayer membranes are typically ____ nm thick

Back

Preview of the front of card 5
View more cards

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