Fatty acids

Question 1

T or F : Fatty acids are not generally found in their free form in living biological systems

Answer 1

T

Question 2

T or F : C4-C8 fatty acids are slightly miscible with water

Answer 2

T

Question 3

What is the structure of a soap (salt form of a fatty acid)

Answer 3

Question 4

T or F : Branched FA with odd number of carbon atoms are not very common in food

Answer 4

T

Question 5

How many carbon is there is butyric acid?

Answer 5

4

Question 6

How many carbon is there is stearic acid?

Answer 6

18

Question 7

How many carbon is there is palmitic acid?

Answer 7

16

Question 8

What is the systematic name of butyric acic?

Answer 8

Butanoic acid

Question 9

What is the systematic name of lauric acic?

Answer 9

dodecanoic acid

Question 10

What is the systematic name of mystiric acic?

Answer 10

Tetradecanoic acid

Question 11

What is the systematic name of palmitic acic?

Answer 11

hexadecanoic acid

Question 12

What is the systematic name of stearic acic?

Answer 12

octadecanoic acid

Question 13

What is the systematic name of palmitic acic?

Answer 13

hexadecanoic acid

Question 14

What is the systematic name of arachidonic acic?

Answer 14

eicosanoic acid

Question 15

What would be the systematic naming of :
C18:1
C18:2
C18:3

Answer 15

C18:1 : octadecenoic acid
C18:2 : octadecadienoic acid
C18:3 : octadecatrienoic acid

Question 16

T or F: linolenic acid is different than octadecatrienoic acid

Answer 16

F, naming is different but it is the same FA if the double bonds are at 9,12,15

Question 17

What does the number represent in the parentheses of the shorthand system –> C18:2(9,12)

Answer 17

the position of the double bonds.

Question 18

all-cis-docosa-4,7,10,13,16,19-hexa-enoic acid is a FA that contains:
A. 26 Carbon atoms with six cis double bounds B. 22 Carbon atoms with six cis double bounds C. 26 Carbon atoms with six trans double bounds

Answer 18

B

Question 19

What is the common name of trans-oleic acid

Answer 19

elaidic acid

Question 20

The melting point of fatty acids is affected by:
A. The chain length
B. The number of double bonds
C. The double bond configuration, cis or trans
D. All of the above
E. None of the above

Answer 20

All of the above

Question 21

What is the shorthand name of linoleic acid?

Answer 21

C18:2(cis9-cis12)

Question 22

T or F : CLA is a positional isomers of linoleic acid

Answer 22

True, it si the conjugated linoleic acid

Question 23

What is the difference between a positional and geometric isomer

Answer 23

Question 24

What is a conjugated FA?

Answer 24

At least one double bond alternate with single bonds C=C-C=C

Question 25

What are conjugated FA?

Answer 25

FA in which the double bond are separated by a methly group C=C-CH2-C=C

Question 26

What is a mixed bonding system?

Answer 26

The mixed bonding system leads to formation of an ACTIVE METHYLENE group (\*), which is positioned between a conjugated and unconjugated double bonds

Question 27

What is reversion?

Answer 27

phenomenon associated with soybean and fish oils, which is defined as the appearance of objectionable flavor from less oxidation than is required to produce true rancidity

Question 28

What is the bonding configuration responsible for the reversion phenomenon?

Answer 28

Mixed bonding system

Question 29

Long chained polyunsaturated cis fatty acids: A. Give better packed, more stable crystalline lattice that requires high temperature to melt B. Give less stable crystalline lattice than their trans isomers thus the melting point is less C. Have no effect on the stability of the crystalline lattice

Answer 29

B

Question 30

Oleic acid 18:1 cis-9 is considered: A. n3 fatty acid B. n6 fatty acid C. n9 fatty acid D. Not an omega acid

Answer 30

C

Question 31

What are acetylenic fatty acids

Answer 31

less common type of fatty acid with a tipple bond

Question 32

Octadeca 9,12,15-trienoic acid is a fatty acid with: A. 18 C atoms and 3 double bonds B. 9 C atoms with 3 double bonds C. 18 C atoms with no double bonds

Answer 32

A

Question 33

Double bonds that are next to each other and not interrupted by a methylene (CH2) group are called:

Answer 33

Conjugated

Question 34

When the first double bound is located on the third C atom starting the count from the CH3 end, this fatty acid is labelled as:

Answer 34

omega-3

Question 35

T or F : Cis-to-trans conversion is often the main mechanism for oils becoming plastic fats during hydrogenation, rather than the desired reduction in the degree of unsaturation

Answer 35

T

Question 36

Complete : The cis‐configuration in oleic acid causes a bending of about \_\_\_\_

Answer 36

40˚

Question 37

T or F : the odd number carbon chains will have a lower melting point

Answer 37

true -- \> Odd‐numbered as well as unsaturated fatty acids cannot be uniformly packed into a crystalline lattice as can the saturated and even‐numbered

Question 38

T or F : The molecular arrangement in the crystalline lattice of unsaturated fatty acids is not strongly influenced by trans double bonds

Answer 38

True because the trans double bonds doesn't create a kink in the structure

Question 39

T or F : The omega nomenclature system is based on the assumption that all natural fatty acids are in the cis form and the double bonds will be always be unconjugated

Answer 39

True

Question 40

What is the most common CLA

Answer 40

rumeric acid (C18:2)

Question 41

Which one would have a lower melting point : oleic or omega-9?

Answer 41

omega-9 because it is automatically cis and oleic might be a trans because it is not specified

Question 42

Which one has a lower melting point, the omega-6 or omega-3 family?

Answer 42

omega-3 because it means that more double bonds since the first one is at carbon 3 from the methyl end

Question 43

Which one has a lower melting point : gamma-linoleic or linoleic

Answer 43

gamma linoleic (C18:3) has a lower melting point than linoleic (C18:2)

Question 44

True or False : linoleic systematic name means that there is always 2 doubles bonds.

Answer 44

false, the gamma-linoleic has 3. linoleic means it will be 18 carbons but doesn't specifiy the number of double bonds. However, the most common one is C18:2(9,12)

Question 45

Which one has the highest melting point : elaidic or stearic

Answer 45

elaidic (C18:1 (tr9)) has a lower melting point than stearic (C18:0)

Question 46

Which one would have a lower melting point : oleic acid or cis-2-octadecenoic aicd

Answer 46

oleic acid since it is C18:1(9) and the cis-2-octadecenoic acid double bond is at the end of the chain.