Lipids 1 Flashcards
What is the structure of a fatty acid?
Polar (soluble) carboxylic acid ‘head’.
Non-polar (insoluble) hydrocarbon chain ‘tail’.
What are the two types of unsaturated fatty acids?
Monounsaturated (MUFAs) - only one double bond in chain.
Polyunsaturated (PUFAs) - multiple double bonds in chain.
What does the stability of a fatty acid depend on?
Length, degree of saturation.
What is the difference between cis and trans double bonds?
Cis = two hydrogen atoms on the same plane.
Trans = two hydrogen atoms in opposite planes.
Describe the storage lipid triacylglycerol (TAG).
Formed of three fatty acid chains joined in a glycerol backbone by ester bonds.
Neutral - do not carry charge, are not soluble in water.
How are membrane lipids categorised?
Initially into phospholipids and glycolipids.
Then by backbone group - glycerol or sphingosine.
Describe the structure of the phospholipid bilayer.
Hydrophilic heads on the outside, facing water. Hydrophobic tails on the inside.
This dual nature of the same molecule means they are classed as amphipathic.
What are the 2 main categories of hormone?
Eicosanoids and steroids.
What molecule are steroid hormones formed from?
Cholesterol.
What are the classifications of steroid hormones?
Sex hormones, glucocorticoids, mineralocorticoids, synthetic steroids.
How are fatty acids produced?
Acetyl CoA + CO2 + ATP + biotin -> Malonyl CoA (by acetyl-CoA carboxylase)
Fatty acid synthase donates 2 carbons from malonyl CoA to acetyl CoA, with addition of 4 hydrogens and 2 electrons.
Continues until palmitate (16 carbons) is formed.
Where does the process of lengthening fatty acid chains take place?
Smooth endoplasmic reticulum / mitochondria.
Describe the process of desaturation of fatty acids.
Fatty acid desaturated by fatty acyl-CoA desaturase, NADPH molecule oxidised to produce 2H2O molecules.
Describe the formation of eicosanoids.
Phospholipids + phospholipase A2 -> Arachindonate
Arachidonate + cyclooxygenase -> prostaglandin G2 -> prostaglandin H2
What are the precursors of TAGs?
Fatty acyl-CoA, glycerol 3-phosphate.