Ch 5 - Lipid Structure And Function

Question 1

Lipid

Answer 1

Characterized by insolubility in water and solubility in nonpolar organic solvents

Question 2

Amphipathic

Answer 2

Molecules with this characteristic have a hydrophilic and a hydrophobic region. Polar head is hydrophilic. The fatty acid tail is hydrophobic

Question 3

Phospholipids

Answer 3

Contain a phosphate and an alcohol that comprise the polar head group joined to a hydrophobic fatty acid tail by phosphodiester linkages

Question 4

Glycerol

Answer 4

3 carbon alcohol

Forms phosphoglycerides or glycerophospholipids

Question 5

Saturated fatty acid

Answer 5

The tails have only single bonds
Carbon bond is considered saturated when it is bound to 4 other atoms with no pi bonds
Greater van der Waals forces and more stable structure

Question 6

Unsaturated fatty acid

Answer 6

Includes one or more double bond which introduce kinks into the fatty acid chain which makes it difficult for them to stack and solidify

Question 7

Glycerophospholipids

Answer 7

Also called phosphoglycerides
Phospholipids that contain a glycerol backbone bonded by ester linkages to two fatty acids and by a phosphodiester linkage to a highly polar head group

Question 8

Sphingolipids

Answer 8

Sphingosine or sphingoid backbone

Not all are phospholipids

Question 9

Glycolipid

Answer 9

Any lipid containing glycosidic bonds to sugar

Question 10

Four major subclasses of sphingolipids

Answer 10

Ceramides
Sphingomyelins
Glycosphingolipids
Gangliolipids

Question 12

Ceramide

Answer 12

Major class of Sphingolipid with single hydrogen atom as its head group

Question 13

Sphingomyelins

Answer 13

Major class of sphingolipids that are also phospholipids
Have either phosphatidylcholine or phosphatidylethanolamine as a head group and thus contain a phosphodiester bond
Major component in plasma membranes of cells producing myelin, the insulating sheath for axons
No net charge

Question 14

Glycosphingolipids

Answer 14

Major class of sphingolipids that are also glycolipids 
Not phospholipids, ie no phosphodiester linkages mainly found on outer surface of plasma membrane 
Further classified as either cerebrosides or globosides

Question 15

Cerebrosides

Answer 15

Glycosphingolipids with a single sugar

No net charge at physiological pH

Question 16

Globosides

Answer 16

Glycosphingolipids with two or more sugars

No net charge at physiological pH

Question 17

Waxes

Answer 17

Esters of long chain fatty acids with long chain alcohols

Question 18

Terpenes

Answer 18

Metabolic precursors to steroids and other lipid signaling molecules
Class of lipids built from isoprene (C5H8) moieties which share a common structural pattern with carbons grouped in multiples of 5

Question 19

Monoterpenes (C10H16)
Sesquiterpenes
Diterpenes
Triterpenes
Tetraterpenes

Answer 19

Mono have two isoprene units and 10 Cs
Sesqui - 3 isoprene with 15 Cs
Di- 4 isoprenes with 20 Cs (vit A)
Tri - 6 isoprenes with 30 Cs - converted to cholesterol and various other steroids
Tetra - 8 isoprenes with 40 Cs - Carotenoids
Polyterpene- a lot (rubber)

Question 20

Terpenoids

Answer 20

Also called isoprenoids

Derivatives of terpenes that have undergone oxygenation or rearrangement of the carbon skeleton

Question 21

Steroids

Answer 21

Metabolic derivatives of terpenes
Characterized by having four cycloalkane rings fused together: three cyclohexane and one cyclopentane
Functionality is determined by oxidation status of these rings as well as functional groups they carry

Question 22

Steroid hormones

Answer 22

Steroids that act as hormones meaning they are secreted by endocrine glands into the bloodstream and then travel on protein carriers to distant sites where they can bind to specific high affinity receptors and alter gene expression (testosterone, various estrogens, cortisol, and aldosterone)

Question 23

Cholesterol

Answer 23

Steroid - major component of phospholipid bilayer and responsible for mediating membrane fluidity
Amphipathic
Precursor to steroid hormones, bile acids and vit D

Question 24

Prostaglandins

Answer 24

Produced by almost all cells in the body. 20-carbon molecules are unsaturated carboxylic acids derived from arachidonic acid and contain one 5-carbon ring
Many cells responsible for regulating synthesis of cyclic adenosine monophosphate cAMP which then moderates many other hormones
Raises body temp associated with fever and pain - NSAIDS inhibit

Question 25

Fat soluble vitamins

Answer 25

Vitamin A (carotene)
Vitamin D (cholecalciferol) 
Vitamin E (tocopherols and tocotrienols) 
Vitamin K (phylloquinone K1, and menaquinones K2)

Question 26

Vitamin A

Answer 26

Carotene unsaturated hydrocarbon important for vision, growth and development and immune function Most significant is aldehyde form - retinal important for light sensing Retinol is storage form and can be oxidized to retinoic acid - a hormone that regulates gene expression during epithelial development

Question 27

Vitamin D

Answer 27

Cholecalciferol Consumed in the form of UV light driven reaction with skin In liver and kidneys is converted to calcitriol (biologically active form of vitamin D) Increases calcium and phosphate uptake in intestines

Question 28

Vitamin E

Answer 28

Closely related lipids called tocopherols and tocotrienols Characterized by substituted aromatic ring with a long isoprenoid side chain and are hydrophobic Prevents oxidative damage

Question 29

Vitamin K

Answer 29

Group of compounds including phylloquinone (K1) and menaquinones (K2) Important for production of prothrombin important clotting factor for blood Also introduces calcium binding sites in several calcium-dependent proteins

Question 30

Triacylglycerols

Answer 30

Also called triglycerides Composed of three fatty acids bonded by ester linkages to glycerol Great for storing energy because carbon atoms of fatty acids are more reduced than those of sugars which yields twice the amount of energy per gram as carbs And they are hydrophobic do not draw in water or require it Observed as oily droplets in cytosol

Question 31

Adipocytes

Answer 31

Cells that store large amounts of fat found primarily under skin, around mammary glands, and in abd cavity

Question 32

Saponification

Answer 32

Ester hydrolysis of triacylglycerols using a strong base

Question 33

Surfactant

Answer 33

Soap after saponification lowers surface tension at surface of a liquid Soap can “mix” hydrophobic and hydrophilic substances into a colloid and dissolve both hydrophobic on inside of micelles and hydrophobic on outside

Question 34

Gangliosides

Answer 34

Major and most complex group of sphingolipids Polar head groups composed of oligosaccharides with one or more N-acetylneuraminic acid (NANA or sialic acid) molecules at the terminus Have a negative charge No phosphate group so considered glycolipids Play a major role in cell interaction, recognition, and signal transduction