Lipids

Question 1

Phospholipids

Answer 1

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

Question 2

Saturated Fatty Acid

Answer 2

• tails that only have single bonds
• carbon atom is considered saturated when it is bonded to 4 other atoms with no pi bonds
• greater van der waals forces and stable overall structure
• solid at room temperature
• high melting point
• decrease membrane fluidity

Question 3

Unsaturated Fatty Acid

Answer 3

• has one or more double bonds, or rings
• liquid at room temperature
• increase membrane fluidity
• create kinks in chain so inhibition of stacking and solidifying
• at low temperatures these help increase membrane fluidity

Question 4

Glycerophospholipids

Answer 4

• phospholipids that contain a glycerol backbone bonded by ester linkages to two fatty acids and a phosphodiester linkage to a highly polar head group
• named according to their head group

Question 5

Sphingolipids

Answer 5

• have a sphingosine or sphingoid backbone that is a long carbon chain that becomes one of the nonpolar tails of the lipid
• long-chain nonpolar fatty acid tails and polar head groups
• contain a phosphodiester linkage or glycosidic linkages to sugars
• sites of biological recognition at cell surface

Question 6

Glycolipid

Answer 6

any lipid linked to a sugar

Question 7

What are the 4 subclasses of spingolipids?

Answer 7

• ceramide
• sphingomyelins/sphingophospholipids
• glycosphingolipids
• gangliosides

Question 8

Ceramide

Answer 8

has a single hydrogen atom as its head group

Question 9

Sphingomyelins

Answer 9

• major component of cells that produce myelin

- type of sphingophospholipid

Question 10

Sphingophospholipid

Answer 10

• sphingolipids that are also phospholipids
• head group is either phosphatidylcholine or phosphatidylethanolamine so contain a phosphodiester bond
• head groups don’t have a net charge

Question 11

Glycosphingolipids

Answer 11

• sphingolipids with head groups composed of sugars bonded by glycosidic linkages
• type of glycolipid, not a phospholipid
• found on outer surface of membrane
• no net charge

Question 12

Gangliosides

Answer 12

• glycolipids with polar head groups made of oligosaccharides with one or more N-acetylneuraminic acid (NANA) molecules at the terminus
• contain glycosidic linkages

Question 13

Waxes

Answer 13

• contain long-chain fatty acids esterified to long-chain alcohols, do not have a polar head group
• used as protection against evaporation and parasites in plants/animals
• entirely nonpolar and hydrophobic
• pliable solids at room temp
• most soluble in pure organic solvents (“like dissolves like”)
• prevent water loss across the plasma membrane

Question 14

Terpenes

Answer 14

• chemicals that are the metabolic precursors to steroids and other lipid signaling molecules
• lipids built from isoprene (C5H8) moieties

Question 15

Monoterpenes

Answer 15

• contain 2 isoprene units

- C10H16

Question 16

Sesquiterpenes

Answer 16

contain 3 isoprene units

Question 17

Diterpenes

Answer 17

• contain 4 isoprene units

- Ex. Vitamin A

Question 18

Triterpenes

Answer 18

• contain 6 isoprene units

- can be converted to cholesterol and other steroids

Question 19

Tetraterpenes

Answer 19

• contain 8 isoprene units

- Ex. carotenoids

Question 20

Terpenoids

Answer 20

• isoprenoids
• derivatives of terpenes that have undergone oxygenation or rearrangement of carbon skeleton
• contribute to steroid biosynthesis

Question 21

Steroids

Answer 21

• signaling lipid
• have 4 cyclo-alkane rings fused together
• nonpolar
• Ex. cholesterol

Question 22

Steroid Hormones

Answer 22

• secreted by endocrine glands into bloodstream then travel on protein carriers to distant sites
• can alter gene expression levels and metabolism

Question 23

Cholesterol

Answer 23

• major component of phospholipid bilayer
• mediates membrane fluidity
• amphipathic (both hydrophobic and hydrophilic)
• precursor to steroid hormones, bile acid, and vitamin D

Question 24

What does cholesterol do for the membrane at high temperatures?

Answer 24

keeps membrane intact by moving phospholipids closer together and thus decreasing membrane fluidity

Question 25

What does cholesterol do for the membrane at low temperatures?

Answer 25

increases distance between phospholipids and thus increasing membrane fluidity

Question 26

Progstaglandins

Answer 26

- produced by nearly all cells in body - 20-carbon molecules with unsaturated carboxylic acid derived from arachidonic acid (contain one 5 carbon ring) - downstream effects including regulation of cAMP synthesis, smooth muscle function, influence on sleep-wake cycle, and increased body temperature

Question 27

What vitamins are fat soluble?

Answer 27

A, D, E, K

Question 28

Vitamin

Answer 28

- essential nutrient | - not adequately synthesized by body so must include in diet

Question 29

Vitamin A (Carotene)

Answer 29

-unsaturated, hydrocarbon important in vision, growth/development, immune function

Question 30

Retinal

Answer 30

- metabolite of vitamin A - often bound to protein opsin - converts light energy in photons to chemical energy

Question 31

Retinol

Answer 31

- storage form of vitamin A | - can be oxidized to retinoic acid (hormone that regulates gene expression during epithelial development)

Question 32

Vitamin D (Cholecalciferol)

Answer 32

consumed and formed by UV light driven reaction in skin

Question 33

Calcitriol

Answer 33

- form that the liver and kidneys convert vitamin D to - biologically active form of vitamin D - increases calcium and phosphate uptake in intestines

Question 34

Vitamin E

Answer 34

- group of lipids called tocopherols (biological antioxidants) and tocotrienols - characterized by substituted aromatic ring with long isoprenoid side chain - hydrophobic - help prevent oxidative damage

Question 35

Vitamin K

Answer 35

- vital to post-translational modifications required to form prothrombin (blood clotting factor) - required to introduce calcium-binding sites on calcium-dependent proteins

Question 36

Triacylglycerols

Answer 36

- used for energy storage - oxidation of these results in 2x the amount of energy per gram as carbs - hydrophobic. insoluble in water - composed of 3 fatty acids bonded by ester linkages to glycerol - nonpolar

Question 37

Adipocytes

Answer 37

special cells in animals that store large amounts of fat

Question 38

Free Fatty Acids

Answer 38

unesterified fatty acids with free carboxylate group

Question 39

Saponification

Answer 39

ester hydrolysis of triacylglycerols using a strong base

Question 40

Surfactant

Answer 40

- lowers the surface tension at the surface of a liquid | - serves as a detergent or emulsifier

Question 41

What phosphoglyceride is abundant in mitochondrial membranes?

Answer 41

Diphosphatidylglycerol (Cardiolipin)

Question 42

12:0

Answer 42

Laurate

Question 43

14:0

Answer 43

Myristate

Question 44

16:0

Answer 44

Palmitate

Question 45

18:0

Answer 45

Stearate

Question 46

20:0

Answer 46

Arachidate

Question 47

16:1

Answer 47

Palmitoleate

Question 48

18:1

Answer 48

Oleate

Question 49

18:2

Answer 49

Linoleate

Question 50

20:4

Answer 50

Arachidonate

Question 51

What are the 10 common phosphoglycerides found in membranes?

Answer 51

- Serine - Ethanolamine - Choline - Inositol - Glycerol - Phosphatidylcholine - Phosphatidylethanolamine - Phosphatidylserine - Phosphatidylinositol - Diphosphatidylglycerol

Question 52

What kind of bond is found in Triacylglycerol?

Answer 52

glycerol with 3 carbon chains bound by ESTER LINKAGES

Question 53

What is the general structure of a phospholipid?

Answer 53

glycerol, 2 FA tails, PO4 bonded to ROH (alcohol)

Question 54

What is the general structure of a Phosphatide?

Answer 54

glycerol, 2FAs, PO4

Question 55

What type of bond is found in Sphingomyelin?

Answer 55

Amide Link

Question 56

Which is more stable/less reactive, an amide link or an ester link?

Answer 56

Amide Link

Question 57

What does it mean to glycosylate a phospholipid?

Answer 57

add sugar (glycosylate) to a fat

Question 58

What is a cerebroside?

Answer 58

- it is a phospholipid that has a sugar attached (glucose, galactose) - the sugar is almost always found on the extracellular side of the membrane

Question 59

All ___ hormones are derived from cholesterol

Answer 59

steroid

Question 60

Cholesterol in the membrane ___ fluidity at high temperatures. It does this by increasing __ __ ___ interactions.

Answer 60

- decreases | - van der waals

Question 61

The presence of cholesterol in the membrane __ boiling

Answer 61

prevents

Question 62

In general, cholesterol ___ membrane fluidity. It does this by ___ FA tails of lipids from packing and sticking together.

Answer 62

- increases | - preventing

Question 63

Cholesterol is considered ___ because it has a polar -OH group, but is mostly nonpolar overall.

Answer 63

amphipathic

Question 64

Prostaglandins are ____ molecules derived from ___ ___

Answer 64

- signaling | - fatty acids (specifically arachidonate)

Question 65

Fat Soluble Vitamins are ___ for enzymes that are non-polar.

Answer 65

cofactors