Biochemistry of lipids

Question 1

what do lipids exclusively contain?

Answer 1

carbon hydrogen and oxygen

Question 2

the structure of triglycerides are based around

Answer 2

one molecule of glycerol

Question 3

joined to each glycerol molecule are…

Answer 3

three fatty acid chains, these are long hydrocarbons with a carboxyl group on one end

Question 4

where do the fatty acids join on the glycerol molecule

Answer 4

where the OH groups are

Question 5

the reaction that joins fatty acids and OH groups is a

Answer 5

condensation reaction, because three fatty acids join to 3 different OH groups three condensation reactions are effectively taking place. this produces 3 molecules of water

Question 6

fatty acids are said to be saturated if

Answer 6

there are NO C=C DOUBLE BONDS in the hydrocarbon chain

Question 7

features of saturated fatty acids

Answer 7

form straight chains and have high melting points

Question 8

fatty acids are said to be unsaturated if

Answer 8

there ARE C=C double bonds in the hydrocarbon chains

Question 9

features of unsaturated fatty acids

Answer 9

form bent chains and have low melting points

Question 10

if fatty acids have MORE THAN ONE C=C DOUBLE BOND they are said to be

Answer 10

polyunsaturated

Question 11

the structure of phospholipids is similar to that of …. and why

Answer 11

triglycerides as they are still based around one molecule of glycerol. they also have two fatty acid chains and a phosphate group

Question 12

phospholipids are said to be …….

Answer 12

polar molecules

Question 13

(phospholipids) the phosphate head is

Answer 13

hydrophilic (water loving)

Question 14

(phospholipids) fatty acid tails are

Answer 14

hydrophobic

Question 15

when phospholipids mix with water they can form

Answer 15

droplets or a phospholipid bilayer

Question 16

why can phospholipids form droplets

Answer 16

they form droplets when the phosphate heads are in contact with the water and the fatty acid tails are excluded from it

Question 17

phospholipid bilayer

Answer 17

this captures a pocket of water within the double layer. this structure is found in cell membranes

Question 18

how do you test for lipids

Answer 18

using the emulsion test. add a sample to a grease free test tube. then add ethanol to the sample and mix by inverting several times. add water to the test tube. if a cloudy white emulsion or precipitate is formed then a lipid is present.