Lipids & Membrane Structure Flashcards
Describe the fluid-mosaic model
Islands of proteins in a sea of lipid
How can you identify a plasma membrane?
Carbohydrates on the extracellular surface
What are integral/intrinsic proteins?
Embedded in bilayer
Alpha helices or beta pleated sheets
How are anchored proteins attached to membranes?
By covalently bound fatty acids
How are peripheral/extrinsic proteins attached to the membrane?
Ionic interactions with integral proteins OR polar head group of phospholipids
What are lipids soluble in?
Fat and organic solvents
What are the functions of lipids? (4)
Energy store (eg. Triacylglycerol)
Precursors for vitamins and hormones (eg. Steroids)
Bile acids (eg. Cholic acid)
Membrane structure (phospholipid bilayer)
What can the polar head group of a phospholipid be?
Serine
Choline
Ethanolamine
Inositol
How is the polar head group attached to the glycerol backbone?
Through a phosphate group
How are the fatty acids linked to the glycerol backbone?
Ester bonds
What does amphipathic mean?
Has both hydrophilic and hydrophobic components
What is the name of a glycerophospholipid with serine as its polar head group?
Phosphotidylserine
What is the name of a glycerophospholipid with choline as its polar head group?
Phosphatidylcholine
What is the name of a glycerophospholipid with ethanolamine as its polar head group?
Phosphatidylethanolamine
What is the name of a glycerophospholipid with inositol as its polar head group?
Phosphatidylinositol
Give an example of a phospholipid without a glycerol backbone
Sphingomyelin
What is sphingomyelin made up of?
Choline and ceramide (sphingosine with a fatty acid chain)
Give three examples of saturated fatty acids (with ratios)
Stearic acid (18:0)
Palmitic acid (16:0)
Myristic acid (14:0)
Give an example of a monounsaturated acid (with ratio)
Oleic acid (18:1)
9
Give an example of a polyunsaturated fatty acid (with ratio)
Arachidonic acid (20:4)
5, 8, 11, 14
What is the structure of cholesterol?
Hydroxyl group
Rigid planar steroid ring structure
Hydrocarbon tail
What is fluidity?
The ease with which lipid molecules move about in the plane of the bilayer
Which lipids are found in each of the layers of the cell membrane?
Extracellular: phosphatidylcholine and sphingomyelin
Intracellular: phosphatidylserine and phosphatidylethanolamine
Explain how shorter fatty acid chain lengths affect membrane fluidity.
Reduced tendency for hydrocarbon chains to interact
More fluid
Explain how having unsaturated fatty acid chains affects membrane fluidity.
Double bonds create “kinks”
Less stable van der Waals forces with other phospholipids
More fluid
Explain how high cholesterol affects membrane fluidity.
Restricts random movement of polar heads
Less fluid
What are cholesterol-rich regions called?
Lipid rafts
What are the essential fatty acids?
Linoleic acid (18:2) 9, 12
Linolenic acid (18:3) 9, 12, 15
Where do we get our essential fatty acids?
Dietary fat
Why are essential fatty acids important?
Give rise to arachidonic acid
Used to form eicosanoids and important for regulating membrane fluidity
What does a lack of essential fatty acids cause? (4)
Scaly dermatitis
Hair loss
Impaired wound healing
Compromised inflammatory and immune responses
