Chapter 5 - Lipid Structure and Function

Question 1

Amphipathic

Answer 1

a molecule that has both hydrophilic and hydrophobic regions

Question 2

Phospholipid

Answer 2

phosphate and alcohol make up polar head group, joined to hydrophobic FA tail by phosphodiester linkages

Question 3

Lipid properties depend on:

Answer 3

the degree of saturation in fatty acid chains and the functional groups to which the fatty acid chains are bonded

Question 4

Ceramide

Answer 4

simplest sphingolipid, has one hydrogen atom as its head group

Question 5

Sphingomyelin

Answer 5

no net charge, major components in plasma membranes of cells producing myelin (oligodendrocytes and Schwann cells)

Question 6

Cerebrosides

Answer 6

glycosphingolipids on outer surface of plasma membrane with a single sugar

Question 7

Globosides

Answer 7

same as cerebrosides but have two or more sugars, no net charge

Question 8

Gangliosides

Answer 8

glycolipids with polar head groups composed of oligosaccharides with one or more N-acetylneuraminic acid (NANA) molecules at the terminus, and a negative charge

Question 9

Waxes

Answer 9

esters of long-chain FAs with long-chain alcohols

Question 10

Terpenes

Answer 10

metabolic precursors to steroids, class of lipids built form isoprene (C5H8), a single terpene unit contains two isoprene units

Question 11

Steroids

Answer 11

metabolic derivatives of terpenes, they have 4 cycloalkane rings fused together: three cyclohexane and one cyclopentane

Question 12

What determines steroid functionality?

Answer 12

Oxidation status of the rings and functional groups present, they are nonpolar

Question 13

Where are steroids secreted?

Answer 13

act as hormones, so secreted by endocrine glands into the bloodstream and travel on protein carriers to sites where they bind to specific high-affinity receptors and alter gene expression levels

Question 14

What is the importance of cholesterol?

Answer 14

major component of phospholipid bilayer, mediates membrane fluidity, is amphipathic

Question 15

What are prostaglandins?

Answer 15

made by almost all cells in the body, 20-carbon molecule of unsaturated COOH derived from arachidonic acid, contains one five-carbon ring

Question 16

What is the function of prostaglandins?

Answer 16

paracrine/autocrine signaling molecules, regulates synthesis of cAMP

Question 17

How do nonsteroidal anti-inflammatory drugs (NSAIDs) work?

Answer 17

they inhibit the enzyme cyclooxygenase (COX), which aids in the production of prostaglandins

Question 18

What are some downstream effects of prostaglandins?

Answer 18

smooth muscle function, influence over sleep-wake cycle, elevation of body temp associated with fever and pain

Question 19

Vitamin A (carotene)

Answer 19

unsaturated hydrocarbon for vision, growth and development, and immune function

Question 20

Retinal

Answer 20

an aldehyde metabolite of vitamin A, component of the light-sensing molecular system in human eye

Question 21

What is calcitriol?

Answer 21

biologically active form of vitamin D, increases calcium and phosphate uptake in the intestines for bone production

Question 22

Vitamin E

Answer 22

tocopherols and tocotrienols, substituted aromatic ring with long isoprenoid side chain, hydrophobic nature

Question 23

What is the function of tocopherols?

Answer 23

biological antioxidants, aromatic ring reacts with free radicals, destroying them

Question 24

Vitamin K

Answer 24

group of compounds: phylloquinone and menaquinones

Question 25

What is the importance of vitamin K?

Answer 25

vital for posttranslational modifications required to form prothrombin, the clotting factor in blood

Question 26

Why are triacylglycerols specifically used for energy storage?

Answer 26

carbon atoms of FAs are more reduced than sugars, so oxidation yields twice the amount of energy per gram, and second they are hydrophobic, do not draw water and do not require hydration for stability—decreases weight

Question 27

Micelles

Answer 27

tiny aggregates of soap with hydrophobic tails inward and hydrophilic heads outward, thereby shielding hydrophobic lipid tails allowing solvation