Lipid practical

Question 1

Lipids are…

Answer 1

Esters (acylglycerols)

Question 2

Lipids are formed…

Answer 2

In condensation reactions between OH groups of glycerol and COOH groups of fatty acids

Question 3

Fatty acids are…

Answer 3

Carboxylic acids with long chain hydrocarbon tails

Question 4

Saturated

Answer 4

No double bonds

Question 5

Unsaturated

Answer 5

One (monounsaturated) or more (polyunsaturated) double bonds in hydrocarbon tail.

Question 6

Hydrophobic

Answer 6

Water insoluble

Non-polar

Question 7

Higher animals + plants have…

Answer 7

Fatty acids which have 16 - 18 carbon long chain

Question 8

Monopalmitin

Answer 8

Monoacylglycerol

= reaction between 1 of 3 alcohol groups on glycerol and one molecule of palmitic acid

Question 9

Dipalmitin

Answer 9

Diacylglycerol

Question 10

Tripalmitin

Answer 10

Triacylglycerol

Question 11

Plant oils are usually…

Answer 11

Triacylglycerols, with a higher content of unsaturated fatty acids than animal fats => lower melting points

Question 12

Animal fat melting point

Answer 12

Higher than plant fats

Question 13

Animal fats have higher melting point because….

Answer 13

They are more dense (=saturated = more hydrogen) = longer to heat up

Question 14

Olive oil content

Answer 14

Nearly pure triolein 
oleic acid
Palmitic acid
Stearic acid
Linoleic acid
Linolenic acid

Question 15

Almond oil content

Answer 15

Oleic acid, linoleic acid, palmitic acid

Question 16

Phospholipids

Answer 16

Amphipathic =
phosphate head - negatively charged + polar groups -> hydrophilic
Fatty acid tails -> hydrophobic
= lipid bilayer

Question 17

Amphipathic

Answer 17

Both hydrophobic and hydrophilic parts

Question 18

Glycerophospholipids structure

Answer 18

Glycerol + 2 fatty acids + phosphate (attached to alcohol group)

Question 19

Glycerophospholipids examples

Answer 19

Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine

Question 20

Sphingolipids

Answer 20

Sphingosine + 2 fatty acids + phosphate (attached to alcohol)

Question 21

Phosphatidylcholine

Answer 21

Most abundant phospholipid in animals + plants

~50% of the total phospholipids bc it’s a key building block of membrane Bilayers

Question 22

Phosphatidylserine

Answer 22

Distributed widely among animal, plants + microorganisms

Notable sources = myelin from Brain tissue + hen egg yolk

Question 23

Cholesterol properties

Answer 23

Tetracyclic ring system
Amphipathic
Major component of eukaryotic cell membranes

Question 24

Cholesterol functions

Answer 24

Maintains cell fluidity

Biological precursor to steroid hormones, bile salts, vitamin D

Question 25

Chromatography bed

Answer 25

Thin layers of adsorbent spread on a glass/ plastic plate

Question 26

Stationary phase

Answer 26

Silica (polar)

Question 27

Mobility in TLC

Answer 27

More polar a lipid the more it stick to the silica and the less efficient it travels up plate

Question 28

Iodine vapour binds to… + comments…

Answer 28

Unsaturated fatty acids

Brown spots = addition reaction of iodine across double bonds

Question 29

Fluorescence spray binds to… + comments

Answer 29

Nonspecific - all lipids

Fluorescent yellow spots under UV lights

Question 30

Ninhydrin spray binds to… + comments

Answer 30

Amino acids such as phosphatidylserine…

Purple spots - when plate is heated

Question 31

Molybdenum blue bind to… + comments

Answer 31

Specific = phospholipids

Blue spots

Question 32

Increasing hydrophobicity acylglycerols

Answer 32

Mono-> di -> triglycerols