Week 7

Question 1

Lipids

Answer 1

• A structurally diverse group of molecules

- Not defined by their chemical structure

Question 2

What is the defining feature of a lipid?

Answer 2

• hydrophobicity

Question 3

What is used to dissolved lipids

Answer 3

• organic solvents
• 2:1 mixture of chloroform and methanol
  (chloroform is very non polar and lipids will only dissolve in non-polar)

Question 4

What are the 6 biological functions of lipids?

Answer 4

Energy storage, structural elements of biological membranes, signal transduction, enzyme cofactors, vitamins, light-absorbing pigments

Question 5

How are lipids used in energy storage?

Answer 5

• Triacylglycerols (Fats and oils)

Question 6

How are lipids used in the cell membrane?

Answer 6

• Phospholipids and sterols

Question 7

How are lipids used in signal transduction?

Answer 7

• Steriod hormones, prostaglandins

Question 8

How are lipids used in enzyme cofactors?

Answer 8

• Coenzyme Q: mitochondrial electron transport chain

Question 9

Which vitamins contain lipids?

Answer 9

• Vitamins A, D, E, K

Question 10

Which light absorbing pigment is a lipid?

Answer 10

• Carotene

Question 11

Glycolipids

Answer 11

• Contain sugar and lipid portions
• Important constituents of cell membranes
• Covalently linked

Question 12

Lipoproteins

Answer 12

• plasma lipoproteins thats are associated with cardiovascular health and disease

Question 13

Glyco is

Answer 13

• indicator of a carbohydrate

Question 14

The human blood groups are defined by ________ displayed on the outer surfaces of blood cells

Answer 14

Glycolipids

Question 15

Fatty Acids

Answer 15

• building blocks of many complex lipids

- central intermediates in metabolism but free fatty acids present in trace quantities

Question 16

Triacylglycerols

Answer 16

• storage fat

Question 17

Phosphoglycerides

Answer 17

• the major lipids in membranes

- main type of lipid

Question 18

Saturated Fatty Acids

Answer 18

Fatty acids with no double bonds between carbons in the chain

Question 19

Fatty acid

Answer 19

Carboxylic acids with hydrocarbon chains ranging from 4-36 carbons

Question 20

Unsaturated Fatty Acids

Answer 20

-Fatty acids with one or more double bonds in the chain

Question 21

Monosaturated Fatty Acid

Answer 21

• one double bond in chain

Question 22

Polysaturated Fatty Acid

Answer 22

• more than one double bond in the chain (triple bonds are uncommon)

Question 23

How to label fatty acids?

Answer 23

• number 1 assigned to the carboxyl carbon and alpha to the carbon next to it
• n:b where n is the number of carbons in the chain and b is the number of double bonds
• delta c where c is where the double bonds are located on the chain relative to the carboxyl carbon

Question 24

What are the features of commonly occurring fatty acids?

Answer 24

• Have an even number of carbon atoms
• Unbranched
• Cis configuration
• The double bonds in polysaturated fatty acids are methylene bridged, not conjugated
• Separated by a methylene carbon and therefore the bond pattern is double-single-single-double

Question 25

What introduces a kink in the chain of a fatty acid?

Answer 25

- cis configuration

Question 26

What are the commonly occurring saturated fatty acids?

Answer 26

Laurante, Myristate, Palmitate, Stearate, Arachidate

Question 27

How many carbons in Laurate and an example

Answer 27

12; bay, laurel

Question 28

How many carbons in Myristate & an example of it

Answer 28

14; myrtle, nutmeg

Question 29

How many carbons in Palmitate & an example

Answer 29

16; palm

Question 30

How many carbons in Stearate & an example

Answer 30

18; tallow

Question 31

How many carbons in Arachidate & an example

Answer 31

20; peanut

Question 32

Partial hydrogenation of unsaturated fatty acid

Answer 32

- used in manufacturing margarine and similar products can isomerize double bonds, generating trans fats - Trans double bond allows a given fatty acid to have an extended conformation

Question 33

Solubility & Melting pt of saturated fatty acids

Answer 33

- adopt extended conformations and therefore pack in a fairly orderly way - favourable interactions - As chain length increases the melting pt increases and solubility decreases

Question 34

Solubility and Melting pt of unsaturated fatty acids

Answer 34

- pack less regularly due to the kink caused by cis double bond, lowering number of favourable interactions - melting temperature is lowered - less thermal energy required

Question 35

Melting pt of trans fatty acids

Answer 35

- can pack more regularly and show higher melting point than cis forms

Question 36

Esters

Answer 36

Carboxylic acids can combine with alcohols to form esters

Question 37

Anhydrides

Answer 37

Carboxylic acids can combine with acids to form anhydrides