PH1123 - Lipids

Question 1

lipid structural function? (2)

Answer 1

• plasma membrane (phospholipids)

- intracellular organelles

Question 2

lipid energy function? (2)

Answer 2

• energy stores

- insulation (white adipose tissue and brown adipose tissue (thermogenesis))

Question 3

lipid carrier function?

Answer 3

• absorption and transport of fat soluble vitamins (A, D, E, K)

Question 4

lipid messenger function?

Answer 4

• cell signalling

Question 5

examples of simple lipids? (2)

Answer 5

• fats; esters of fatty acids with glycerol (oils are fats in the liquid state
• waxes; esters of fatty acids with higher molecular weight than monohydric alcohols

Question 6

examples of complex lipids? (2)

Answer 6

• phosphoipids

- glycolipids

Question 7

examples of precursor and derived lipids? (3)

Answer 7

• fatty acids
• glycerol
• steroids
• hormones

Question 8

what are triglycerides and their main function?

Answer 8

• they are esters of glycerol and fatty acids

- main storage forms of fatty acids

Question 9

what are the differences between fats and oils? (2)

Answer 9

• fats have all available bonding sites taken up by H (saturated)
• oils have fewer Hs on account of double bonds (unsaturated)

Question 10

what are the two molecules which the backbone of phospholipids are built? (2)

Answer 10

• (phospho)glycerides

- sphingosine

Question 11

what is the structure of a phospholipid? (4)

Answer 11

• one unit of glycerol
• two units of fatty acids
• phosphate group
• N2 containing group

Question 12

what is the polarity of a phospholipid like? (2)

Answer 12

• N2 end tends to attract a H+ and becomes positively charges; polar and water soluble
• fatty acid tails are non-polar and insoluble

Question 13

what is the structure of sphingolipids?

Answer 13

• backbone is sphingosine not glycerol

Question 14

where are sphingolipids mainly found?

Answer 14

• prominent on plasma membrane of cells

Question 15

what are phophatidylinositols? (2)

Answer 15

• precursor molecule for phosphatidylinositol 4,5-bisphosphate (PIP2)
• cleaved to form DAG and IP3

Question 16

what does DAG stand for?

Answer 16

• diacylglycerol

Question 17

what does IP3 stand for?

Answer 17

• inositol triphosphate

Question 18

what are DAG and IP3 examples of?

Answer 18

important secondary messengers

Question 19

why are steroids classified as lipids?

Answer 19

• due to their solubility (they are hydrophobic)

Question 20

what is the structure of steroids?

Answer 20

• four interlocking rings of C atoms with side groups attached to rings

Question 21

what is cholesterol a precursor molecule for? (4)

Answer 21

• bile acids
• sex hormones
• adrenocortical hormones
• vitamin D

Question 22

what is the structure of glycolipids?

Answer 22

• sugar attached to fatty acids

Question 23

what are eicosanoids derived from?

Answer 23

derived from eicosa (-C20) polyenoic fatty acids

Question 24

example of eicosanoids and function? (2)

Answer 24

• prostaglandins

- they act as local hormones and cause muscle contraction and inflammation