Chapter 5: Lipid structure and function

Question 1

Each of the phospholipid membrane components is an ________________ molecule, meaning that it has both hydrophilic and hydrophobic regions.

Answer 1

Amphipathic

Question 2

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

Answer 2

Phospholipids

Question 3

Fully ______________ fatty acid tails will have only single bonds; the carbon atom is considered saturated when it is bonded to 4 other atoms, with no pi bonds.

Answer 3

Saturated fatty acids

Question 4

_________________, such as those in butter, have greater van der Waals forces and a more stable overall structure. Therefore, they form solids at room temperature.

Answer 4

Saturated fatty acids

Question 5

An ______________ fatty acid includes one or more double bonds.

Answer 5

Unsaturated fatty acid

Question 6

__________________ have double bonds that introduce kinks into the fatty acid chain, which makes it difficult for them to stack and solidify.

Answer 6

Unsaturated fatty acids

Question 7

___________________ (or __________________) are specifically those 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.

Answer 7

• Glycerophospholipids
• Phosphoglycosides

Question 8

__________________ is the name of a glycerophospholipid with a choline head group.

Answer 8

Phosphotidylcholine

Question 9

____________________ is the name of a glycerophospholipid with an ethanolamine head group.

Answer 9

Phosphotidylethanolamine

Question 10

Sphingolipids have a ______________ or _____________ (sphingosine-like) backbone.

Answer 10

• Spingosine
• Sphingoid

Question 11

Other sphingolipids contain glycosidic linkages to sugars; any lipid linked to a sugar can be termed _____________.

Answer 11

Glycolipid

Question 12

Sphingolipids are divided into 4 major subclasses, differing by their head group:
- _______________
- _______________
- _______________
- _______________

Answer 12

• Ceramide
• Sphingomyelins (sphingophospholipids)
• Glycosphingolipids
• Gangliosides

Question 13

The simplest sphingolipid is _____________, which has a single hydrogen atom as its head group.

Answer 13

Ceramide

Question 14

_________________ are the major class of sphingolipids that are also phospholipids (____________________). These molecules have either phosphocholine or phosphoethanolamine as a head group, and thus contain a phosphodiester bond. Head groups have no net charge.

Answer 14

• Sphingomyelins
• Sphingophospholipids

Question 15

Sphingolipids with head groups composed of sugars bonded by glycosidic linkages are considered glycolipids, more specifically _________________. These molecules are not phospholipids because they contain no phosphodiester linkage.

Answer 15

Glycosphingolipids

Question 16

Glycosphingolipids are found mainly on the outer surface of the plasma membrane and can be further classified as _______________ (single sugar) or _______________ (two or more sugars)

Answer 16

• Cerebrosides
• Globosides

Question 17

______________ (sphingolipids) are glycolipids that have polar head groups composed of oligosaccharides with one or more N-acetylneuraminic acid (NANA, or sialic acid) molecules at the terminus and a negative charge.

Answer 17

Gangliosides

Question 18

_____________ are considered glycolipids because they have a glycosidic linkage and no phosphate group.

Answer 18

Gangliosides

Question 19

_________ are esters oof long-chain fatty acids with long-chain alcohols.

Answer 19

Waxes

Question 20

___________ are a class of lipids built from isoprene (C5H8) moieties and share a common structural pattern with carbons grouped in multiples of five.

Answer 20

Terpenes

Question 21

Terpenes are grouped according to the number of isoprene units present; a single terpene unit contains two _____________ units.

Answer 21

Isoprene

Question 22

________________ (C10H16), which are abundant in both essential oils and turpentine, contain 2 isoprene units.

Answer 22

Monoterpenes

Question 23

________________ contain three isoprene units.

Answer 23

Sesquiterpenes

Question 24

______________ contain 4 isoprene units.

Answer 24

Diterpenes

Question 25

______________, with 6 isoprene units, can be converted to cholesterol and various steroids.

Answer 25

Triterpenes

Question 26

______________, like beta-carotene and lutein, are _________________ and have 8 isoprene units.

Answer 26

- Carotenoids - Tetraterpenes

Question 27

______________, also sometimes referred to as ______________, are derivatives of terpenes that have undergone oxygenation or rearrangement of the carbon skeleton.

Answer 27

- Terpenoids - Isoprenoids

Question 28

____________ are metabolic derivatives of terpenes. Large number of carbons and hydrogens (3 cyclohexane and 1 cyclopentane) make steroids nonpolar.

Answer 28

Steroids

Question 29

______________ (amphipathic molecule) is a steroid of primary importance. It is a major component of the phospholipid bilayer and is responsible for mediating membrane fluidity.

Answer 29

Cholesterol

Question 30

________________ are 20-carbon molecules that are unsaturated carboxylic acids derived from arachidonic acid and contain 1 five-membered ring.

Answer 30

Prostaglandins

Question 31

The fat-soluble vitamins include _____________, ______________, _____________, _______________.

Answer 31

- Vitamin A - Vitamin D - Vitamin E - Vitamin K

Question 32

_____________, or _____________, is an unsaturated hydrocarbon that is important in vision, growth and development, and immune function.

Answer 32

- Vitamin A - Carotene

Question 33

The most significant metabolite of vitamin A is the aldehyde form, ____________, which is a component of the light-sensing molecular system in the human eye.

Answer 33

Retinal

Question 34

___________, the storage form of vitamin A, is also oxidized to retinoic acid, a hormone that regulates gene expression during epithelial development.

Answer 34

Retinol

Question 35

_____________, or ______________, can be consumed or formed in a UV light-driven reaction in the skin.

Answer 35

- Vitamin D - Cholecalciferol

Question 36

In the liver and kidneys, vitamin D is converted to ______________, the biologically active form of vitamin D.

Answer 36

Calcitriol

Question 37

A lack of vitamin D can result in ___________, a condition seen in children and characterized by underdeveloped, curved long bones as well as impeded growth.

Answer 37

Rickets

Question 38

_______________ characterizes a group of closely related lipids called tocopherols and tocotrienols.

Answer 38

Vitamin E

Question 39

______________ is actually a group of compounds, including phylloquinone (K1) and menaquinones (K2).

Answer 39

Vitamin K

Question 40

_______________ is vital to the posttranslational modifications required to form prothrombin, an important clotting factor in the blood.

Answer 40

Vitamin K

Question 41

_______________, also called _______________, are composed of three fatty acids bonded to ester linkages to glycerol.

Answer 41

- Triacylglycerols - Triglycerides

Question 42

________________ is the ester hydrolysis of triacylglycerols using a strong base.

Answer 42

Saponification

Question 43

Traditionally, the strong base in saponification is used is ________, the common name for sodium or potassium hydroxide.

Answer 43

Lye

Question 44

Soaps can act as ______________. A _____________ lowers the surface tension at the surface of a liquid, serving as detergent or emulsifier.

Answer 44

Surfactant

Question 45

If we try to combine an aqueous solution and oil, as with vinegar and olive oil in salad dressing, these solutions will remain in separate phases. If we were to add soap, the two phases would appear to combine into a single phase, forming a ______________.

Answer 45

Colloid

Question 46

The formation of colloid occurs because of the formation of ____________: tiny aggregates of soap with the hydrophobic tails turned inward and the hydrophilic heads turned outward, thereby shielding the hydrophobic lipid tails and allowing for overall salvation.

Answer 46

Micelles