Lipids

Question 1

What structural component of lipids determines their function and why?

Answer 1

the polar head group (that is attached to the hydrophobic tails via a phosphodiester linkage) because it interacts with the environment

Question 2

What characteristic of fatty acids determines their fluidity in membranes?

Answer 2

saturation

-saturated FA’s are less fluid

Question 3

Why are saturated FA’s solid at room temperature?

Answer 3

because they stack easily due to presence of only sigma bonds in their hydrocarbon tails, have greater van der Waals foces, and have an overall more stable structure

Question 4

Why are unsaturated FA’s liquid at room temperature

Answer 4

the presence of DB’s in the hydrocarbon tail introduces kinds into the chain which makes it difficult for them to stack and solidify… this is why unsaturated FA’s increase the fluidity of membranes

Question 5

Glycerophospholipids (phosphoglycerides)

Answer 5

phospholipids containing a glycerol backbone with a phosphodiester bond to a highly polar head group

Question 6

Phosphatidylcholine

Answer 6

glycerophospholipid with a choline head group

Question 7

Phosphatidylethanolamine

Answer 7

glycerophospholipid with an ethanolamine head gorup

Question 8

What are some membrane surface properties of glycerophospholipids?

Answer 8

cell recognition, signaling, and binding

Question 9

Sphingoside backbone

Answer 9

glycerol with one of the hydroxyl groups replaced by an amine

Question 10

4 major subclasses of sphingolipids

Answer 10

1. Ceramides
2. Sphingomyelins
3. Glycosphingolipids
4. Gangliosides

Question 11

Ceramide

Answer 11

simplest sphingolipid with an amide head group

Question 12

Sphingomyelins

Answer 12

sphingolipids that are phospholipids and have a phosphodiester bond in their head group

head groups include phosphatidylcholine or phosphatidylethanolamine

major components in the plasma membrane of cells containing myelin (oligodendrocytes and Schwann cells)

Question 13

Glycosphingolipids

Answer 13

sphingomyelins with sugar head groups

mainly found on the outer surface of plasma membrane

Question 14

Cerebrosides

Answer 14

glycosphingolipids containing a single sugar as their head group

Question 15

Globosides

Answer 15

glycosphingolipids containing more than one sugar as their head group

Question 16

Gangliosides

Answer 16

the most complex group of sphingolipids

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

major role in cell interaction, recognition, and signal transduction

Question 17

Isoprene

Answer 17

5 carbon moiety (C5H8)

Question 18

Terpenes

Answer 18

class of lipids that are steroid precursors and are built from isoprene

Question 19

How many isoprene units are in one terpene unit?

Answer 19

2

Question 20

Steroids

Answer 20

4 ring structures (3 cyclohexanes and 1 cyclopentane ring)

Question 21

Prostaglandins

Answer 21

autocrine and paracrine signaling molecules that regulate cAMP levels and have powerful effects on smooth-muscle contraction, body temperature, the sleep-wake cycle, and pain

Question 22

What are the 4 fat-soluble vitamins?

Answer 22

A, D, E, K

Question 23

Carotene

Answer 23

Vitamin A

Question 24

What are two metabolic products of Vitamin A and their functions?

Answer 24

Retinal - vision

Retinoic acid - gene expression and epithelial dvlpmt

Question 25

Cholecalciferol

Answer 25

Vitamin D

Question 26

What is Vitamin D metabolized into and what does this metabolic product do?

Answer 26

Vitamin D is metabolized into Calcitrol in the kidneys
Calcitrol functions regulate calcium and phosphorus homeostasis in the intestines (increases calcium and phosphate absorption), promotes bone formation

Question 27

A Vitamin D deficiency causes:

Answer 27

rickets

Question 28

Tocopherol

Answer 28

Vitamin E

Question 29

Vitamin E function

Answer 29

acts as biological antioxidant

aromatic rings destroy free radicals and prevent oxidative damage

Question 30

Phylloquinone and Menaquinone

Answer 30

group of compounds that make up Vitamin K

Question 31

What are two important roles of Vitamin K?

Answer 31

1. important for the posttranslational modification necessary for the formation of prothrombin
2. required for the introduction of calcium-binding sites on several calcium dependent proteins

Question 32

Triacylglycerols

Answer 32

Lipids that contain one glycerol with three fatty acids attached via ester bonds

Question 33

Why are TAG’s the preferred method of energy storage in the body?

Answer 33

Carbon atoms in lipids are more reduced than those in cabohydrates & TAG’s are the most reduced form of lipids in the body; thus, they provide twice as much energy per gram during oxidation

Question 34

Free fatty acids

Answer 34

unesterified FA’s that travel in the bloodstream

Question 35

Soaps

Answer 35

salts of free FA’s

Question 36

Saponification

Answer 36

the ester hydrolysis of TAG’s using a strong base (such as NaOH or KOH)