Biochemistry 5: Lipid Structure and Function

Question 1

lipids

Answer 1

biomolecules that are insoluble in water and soluble in nonpolar organic solvents

Question 2

phospholipids

Answer 2

polar head = phosphate and alcohol

joined to fatty acid tail with phosphodiester linkages

Question 3

glycerophospholipids

Answer 3

phospholipids with a glycerol backbone

bonded by ester linkages to 2 fatty acids

bonded by a phosphate linkage to a polar head group

Question 4

phosphatidylcholine

Answer 4

a glycerophospholipid with a choline head group

Question 5

phosphatidylethanolamine

Answer 5

a glycerophospholipid with an ethanolamine head group

Question 6

sphingolipids

Answer 6

lipids with a sphingosine or sphingoid backbone

linked to fatty acids and a polar head group

some can be phospholipids because of their phosphodiester linkage

others can be glycolipids because of their glycosidic linkage

Question 7

ceramides

Answer 7

sphingolipids with a single H as it’s head group

Question 8

sphingomyelin

Answer 8

sphingolipids with phosphatidylcholine or phosphatidylethanolamine head have a phosphodiester bond, so are sphingophospholipids

have no net charge

highly present in membranes of cells that produce myelin

Question 9

glycosphingolipids

Answer 9

sphingolipids with head groups of sugars bonded with glycosidic linkages

Question 10

cerebrosides

Answer 10

glycosphingolipids attached to a single sugar moiety

Question 11

globosides

Answer 11

glycosphingolipids attached to two or more sugar moieties

Question 12

gangliosides

Answer 12

sphingolipids with polar head groups of oligosaccharides with one or more N-acetylneuraminic acid (NANA/sialic acid)

have glycosidic linkages so they are glycosphingolipids

Question 13

waxes

Answer 13

esters of long-chain alcohols used as protection against evaporation and parasites in plants and animals

Question 14

terpenes

Answer 14

odiferous steroid precursors made from isoprene subunits

protective compounds made by plants and insects

a single compound has two isoprene units

Question 15

sesquiterpenes

Answer 15

have 3 isoprenes

Question 16

terpenoids

Answer 16

derived from terpenes that underwent oxygenation or rearrangement and addition have similar odiferous characteristics

Question 17

steroids

Answer 17

compounds composed of 4 cycloalkane fused rings

3 hexane and 1 pentane ring

Question 18

steroid hormones

Answer 18

steroids with high affinity receptors

work at low concentrations affect gene expression and metabolism

Question 19

cholesterol

Answer 19

steroid important in membrane fluidity and stability

serves as a precursor to many other molecules

Question 20

prostaglandins

Answer 20

autocrine and paracrine signaling molecules that regulate cAMP levels

affect smooth muscle contractions, body temp, sleep-wake cycle, fever, pain, inflammation

inhibited by NSAID derived from arachidonic acid - 20 carbons, one 5-carbon ring produced by almost all cells

Question 21

fat-soluble vitamins

Answer 21

vitamins A, D, E and K

Question 22

vitamin A (carotene)

Answer 22

vitamin metabolized to retinal, stored as retinol, for vision

oxidized to retinoic acid for gene expression during epithelial development

Question 23

vitamin D (cholecalciferol)

Answer 23

vitamin consumed or made from UV

metabolised to calcitrol in kidneys and liver and regulates calcium and phosphorus homeostasis (increases calcium and phosphate absorption in intestine)

promotes bone formation

Question 24

vitamin E (tocopherols)

Answer 24

vitamin that acts as an antioxidant

aromatic rings with isoprenoid sidechain

Question 25

vitamin K (phylloquinone and (menaquinone)

Answer 25

vitamin important for formation of **prothrombin**, a clotting factor also performs post-translational modifications to create **Ca2+ binding sites**

Question 26

why are lipids so great for energy storage?

Answer 26

carbons in the fatty acid are **more reduced** hydrophobic nature **prevents water weight**, so the molecules are **lighter** also good for **insulation**

Question 27

triacylglycerol

Answer 27

lipids with **one glycerol** attached to **three fatty acids** with an **ester bond** travel between **liver and adipose tissue**

Question 28

free fatty acids

Answer 28

unesterified fatty acids with **free carboxylate group** traveling in bloodstream **noncovalently bound to albumin** form salts called **soaps**

Question 29

saponification

Answer 29

the **ester hydrolysis of triacylglycerol** using a strong base like NaOH or KOH soap can be a **surfactant**

Question 30

Answer 30

isoprene