Lipids Flashcards
What are fatty acids composed of?
A polar (hydrophilic/soluble) carboxylic acid head and non-polar (hydrophobic/insoluble) hydrocarbon tail
What is the ‘omega’ carbon?
The carbon atom furthest from the carboxyl group
What is a ‘saturated’ fatty acid?
One with no double bonds between carbon atoms
What is triacylglycerol? (+ structure)
A storage lipid, 3 fatty acid chains joined in a glycerol backbone by ester bonds
Are storage lipids soluble in water?
Nope
What are the main 2 groups of membrane lipids?
Phospholipids and glycolipids
What are the 2 main groups of hormones?
Eicosanoids and steroids
What are eicosanoids formed from?
Arachidonate
What are steroid hormones formed from?
Cholesterol (ring structures)
What are the classes of steroid hormones?
Sex hormones, glucocorticoids, mineralocorticoids, and synthetic steroids
What is the starting molecule for synthesis of fatty acids?
Acetyl CoA
What is palmitate?
A 16-carbon fatty acid which is the precursor of other long-chained fatty acids - can be lengthened/altered
How are fatty acids lengthened?
Fatty acid synthetase donates 2 carbons from malonyl CoA to acetyl CoA (plus 4H+ and 4e-)
Where/what type is the double bond in palmitoleate and oleate?
Between C9 and C10; it is a cis double bond
What enzyme catalyses introduction of a double bond into the carbon chain?
Fatty acyl-CoA desaturase (oxidative reaction)
Why are linoleate and α-linoleate essential fatty acids?
Hepatocytes cannot introduce double bonds any further than C9 (and they are needed at C12/C15)
What are the precursors for triacylglycerol?
Fatty acyl CoA and glycerol-3-phosphate
How are TAGs formed from phosphatidic acid?
Hydrolysed to form 1,2-diacylglycerol; third fatty acid added by transesterification
Where dos phospholipid synthesis primarily occur?
Surface of the SER
Is cholesterol essential in the diet?
No - can be synthesised from acetate
What is the process called by which fatty acids are released from TAGs?
Lipolysis (catalysed by lipase)
How many carbons does a fatty acid need to have to be able to enter directly into the mitochondrial matrix?
12 or fewer (rare)
How do fatty acids with 14+ carbons enter the mitochondrial matrix?
1) Conversion into fatty acyl-CoA
2) Attached to carnitine (for carnitine shuttle)
3) Fatty acyl carnitine enters matrix via facilitated diffusion
4) Conversion back into acyl-CoA
What are the 3 groups of eicosanoids?
Prostaglandins, thromboxanes, leukotrienes (ALL PARACRINE)
What are the 4 groups of steroid hormones?
Glucocorticoids, sex hormones, mineralocorticoids, synthetic steroids (ALL ENDOCRINE)
