Lipids

Question 1

What are fatty acids composed of?

Answer 1

A polar (hydrophilic/soluble) carboxylic acid head and non-polar (hydrophobic/insoluble) hydrocarbon tail

Question 2

What is the ‘omega’ carbon?

Answer 2

The carbon atom furthest from the carboxyl group

Question 3

What is a ‘saturated’ fatty acid?

Answer 3

One with no double bonds between carbon atoms

Question 4

What is triacylglycerol? (+ structure)

Answer 4

A storage lipid, 3 fatty acid chains joined in a glycerol backbone by ester bonds

Question 5

Are storage lipids soluble in water?

Answer 5

Nope

Question 6

What are the main 2 groups of membrane lipids?

Answer 6

Phospholipids and glycolipids

Question 7

What are the 2 main groups of hormones?

Answer 7

Eicosanoids and steroids

Question 8

What are eicosanoids formed from?

Answer 8

Arachidonate

Question 9

What are steroid hormones formed from?

Answer 9

Cholesterol (ring structures)

Question 10

What are the classes of steroid hormones?

Answer 10

Sex hormones, glucocorticoids, mineralocorticoids, and synthetic steroids

Question 11

What is the starting molecule for synthesis of fatty acids?

Answer 11

Acetyl CoA

Question 12

What is palmitate?

Answer 12

A 16-carbon fatty acid which is the precursor of other long-chained fatty acids - can be lengthened/altered

Question 13

How are fatty acids lengthened?

Answer 13

Fatty acid synthetase donates 2 carbons from malonyl CoA to acetyl CoA (plus 4H+ and 4e-)

Question 14

Where/what type is the double bond in palmitoleate and oleate?

Answer 14

Between C9 and C10; it is a cis double bond

Question 15

What enzyme catalyses introduction of a double bond into the carbon chain?

Answer 15

Fatty acyl-CoA desaturase (oxidative reaction)

Question 16

Why are linoleate and α-linoleate essential fatty acids?

Answer 16

Hepatocytes cannot introduce double bonds any further than C9 (and they are needed at C12/C15)

Question 17

What are the precursors for triacylglycerol?

Answer 17

Fatty acyl CoA and glycerol-3-phosphate

Question 18

How are TAGs formed from phosphatidic acid?

Answer 18

Hydrolysed to form 1,2-diacylglycerol; third fatty acid added by transesterification

Question 19

Where dos phospholipid synthesis primarily occur?

Answer 19

Surface of the SER

Question 20

Is cholesterol essential in the diet?

Answer 20

No - can be synthesised from acetate

Question 21

What is the process called by which fatty acids are released from TAGs?

Answer 21

Lipolysis (catalysed by lipase)

Question 22

How many carbons does a fatty acid need to have to be able to enter directly into the mitochondrial matrix?

Answer 22

12 or fewer (rare)

Question 23

How do fatty acids with 14+ carbons enter the mitochondrial matrix?

Answer 23

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

Question 24

What are the 3 groups of eicosanoids?

Answer 24

Prostaglandins, thromboxanes, leukotrienes (ALL PARACRINE)

Question 25

What are the 4 groups of steroid hormones?

Answer 25

Glucocorticoids, sex hormones, mineralocorticoids, synthetic steroids (ALL ENDOCRINE)