Lipids Flashcards
What are lipids?
biological molecules that are generally insoluble in water
What can lipids be divided into?
Simple - after hydrolysis a maximum of 2 products are produced
Complex - 3 or more products produced
How are lipids classified?
By structure or by function
What are storage lipids?
Fats and oils used as stored forms of energy are derivatives of fatty acids
What are fatty acids?
Carboxylic acids with hydrocarbon chains (4-36 carbons)
What is a saturated hydrocarbon chain?
chain with no double carbon bonds
What does the systematic name of fatty acids include?
Specifies the chain length and number of double bonds
What are triglycerols (triacylglycerols)?
fatty esters of glycerol - 3 fatty acids with a single glycerol molecule
Are triglycerols hydrophilic or hydrophobic?
hydrophobic
What are waxes made out of?
Esters of long chain saturated or unsaturated fatty acids with long chain alcohols
Name some general types of membrane lipids
Glycerophospholipds: 2 fatty acids esterified to G3P Galactolipds and sulpholipids Archaeal tetraether lipids Sphingolipids Sterols
List some features of the phospholipid bilayer
Very low permeability (except water)
permeable to small molecules
need transport proteins
What are some limitations of the phospholipid bilayer?
oversimplified and generalised diagrams
descriptions focus on plasma membrane of mammals
Where are galactolipids found?
chloroplast membranes
What do sulpholipids contain?
sulphonated glucose instead of galactose
Where are sulpholipids found?
In plants, algae and cyanobacteria
inner membranes of chloroplasts
What is one of the most common sulpholipids in plants and algae?
Sulphoquinvosyl dipalmitoylglycerol (SQDG)
What structure synthesises lipids?
Mitochondria
What do membranes have a high content of?
Phospholipids
Where is Cardiolipin found?
Inner mitochondrial membrane
What are sphingolipids made out of?
1 molecule of fatty acid and sphingosine instead of glycerol
polar head and 2 non-polar tails
What are the 3 sphingolipid subclasses?
Shphingomyeline, glycosphingolipids, gangliosides
What is the function of flippases and floppases in a phospholipid bilayer?
Move specific phospholipids against their conc gradient using ATP
What molecules do flippases move across the membrane?
Aminophospholipds and phosphatidylethanolamine from outer in inner against conc gradient
What molecules do floppases move across the membrane?
Phosphatidylcholine, sphingolipid and cholesterol against their conc gradients
What is the function of scramblases?
Facilitate movement of lipids along their concentration gradients without use of ATP
During apoptosis what is the function of aminophospholipids (AP)?
Activation of scramblases allows rapid appearance of AP on the outer surface of plasma membrane where it provides “eat me” signal
Name the three types of Eicosanoids that produce extracellular signals
Prostaglandins, Thromboxanes and Leukotrienes
What do prostaglandins produce extracellular signals for?
Contraction of smooth muscle, fever and inflammation
What do thromboxjnes produce extracellular signals for?
Formation of blood clots
What do leukotrienes produce extracellular signals for?
Contraction of smooth muscle lining in airways to the lungs
What are steroid hormones derivatives of?
Sterols (include sex hormones and glucocorticoids)
What do steroid hormones do?
Circulate in the blood stream bound to carrier proteins and trigger changes in gene expression
What intracellular signal is released under conditions of stress?
Shingomyelinases
