Lipids

Question 1

How are lipids linked to other groups

Answer 1

Covalent bonds

Question 2

What are the three lipid classes

Answer 2

Fatty acids
Triaclylglycerols
Phosphoglycerides

Question 3

What are fatty acids

Answer 3

The building blocks of many complex lipids and are the central intermediates in metabolism

Question 4

What are the molecular components of fatty acids

Answer 4

Are carboxylic acids with hydrocarbon chains

Question 5

What is the difference between saturated and unsaturated fatty acids

Answer 5

Saturated: no c-c double bonds
Unsaturated: have one or more c-c double bonds

Question 6

What does: 18:2 (^9,12) tell us about a certain fatty acid

Answer 6

18: the total number of carbons in the chain
2: the total number of double bonds
^9, 12 position of the 2 double bonds

Question 7

What is partial hydrogenation

Answer 7

The artificial process in which fatty acids are made into trans fatty acids. Trans double bonds are added to the fatty acid to extend the chain and solidify it

Question 8

Name the 5 main fatty acids and their number of carbons

Hint: Let My Pal Stay Around

Answer 8

Laurate: 12
Myristate: 14
Palmate: 16
Stearte: 18
Arachidate: 20

Question 9

What are the solubility and melting point properties of saturated fatty acids

Answer 9

Since the chains pack in an ordered way, van der waals interactions are many. As chain length increases, melting point increases and solubility decreases

Question 10

What are the melting point properties of unsaturated fatty acids

Answer 10

The kinks in the unsaturated fatty acid chains make it pack less regularly. Lowered melting point

Question 11

Name two derivatives of fatty acids and their constituents

Answer 11

Esters : carboxyllic acids + alchol

Anhydrides: esters+ acid

Question 12

What are triacyglycerols

Answer 12

Where the majority of fatty acids are stored: fat as we know it

Question 13

How are triaglycerols

formed

Answer 13

3 fatty acids + 1 glycerol molecule through ester linkages

Question 14

Why are triaglycerorols highly hydrophobic

Answer 14

The polar carboxyllic acids from the fatty acids are linked into esters

Question 15

What is the difference between simple and mixed tricylglycerides

Answer 15

Simple: composed of the same fatty acid in all positions
Mixed: composed of 2 or 3 different fatty acids

Question 16

what do you call the process of adding a phosphate and what does it do

Answer 16

Phosphorylation, it adds a negative charge to molecule and raises water solubility

Question 17

Acetic acid + ethyl alcohol =

Answer 17

Phosphate ester

Question 18

Acetic acid + acetic acid=

Answer 18

Acetic anhydride

Question 19

Phosphoric acid + alcohol =

Answer 19

Phosphate

Question 20

What is a phosphoglyceride

Answer 20

Are the primary constituents of biological membranes

Question 21

What does amphipathic mean and why is it important

Answer 21

A combination of a hydrophilic head and a hydrophobic tail

All lipids are amphipathic and its why they can form lipid bilayers

Question 22

Lipids aggregate in specific forms when in contact with water what are the three types

Answer 22

Micelles: small and roughly spherical, smallest and simplest
Bilayers: double layers of phospholipids. They can fold over to form vesicles. Since their tails are too large to form micelles
Vesicles

Question 23

What does chiral mean

Answer 23

Two molecules that are asymmetric in such a way that the structure and mirror image are superimposable

Question 24

What are enantiomers

Answer 24

Molecules that are mirror images of each other differ in configuration at every chiral atom

Have identical chemical properties and a plane of polarized light is passed through a solution of two is bent in opposite directions

Question 25

What are diasteriomers

Answer 25

Monosaccharides with more than one chiral carbon atom do not have identical. Chemical properties

Question 26

What are D and L sugars

Answer 26

L and d glucose are complete mirror images of each other exept the direction of the OH group

D: right
L: left

Most sugars are d sugars

Question 27

What are the functions of lipids

Answer 27

Energy storage: triacylglycerols
Structural elements of biological memberanes: phospholipids and sterols
Enzyme cofactors: coenzyme q
Vitamins: D A E K
Light absorbing pigments: carotene
Insulation and waterproof coating

Question 28

How are lipid molecules different from proteins, carbs and nucleic acids

Answer 28

The rest have a defined structure, but lipids are defined by their hydrophobicity

Question 29

What are the limits of iodine numbers of lipids

Answer 29

> 70 are oils,

Question 30

What are the structural properties that determine the melting temperatures of various fatty acids

Answer 30

Chain length and degree of unsaturation

Question 31

Why are unsaturated fatty acids most stable

Answer 31

In the extended form, they pack tightly together van der waals forces are many so lots of energy needed to break bonds = high melting points

Question 32

If cis double bonds lower the melting point, why do the presence of trans double bonds raise the melting point

Answer 32

Trans double bonds do not change the geometry of the chain much

Question 33

What structural property of a lipid allow them to be the main components of biological membranes

Answer 33

Their amphipathic property allows them to aggregate into bilayers

Question 34

Why are triaglycerols such a good source of fuel

Answer 34

They are insoluble, so large amounts can be stored in cells without increasing the osmotic pressure in cytosol