11-Chemistry of Lipids(fatty acids)

Question 1

biological molecules that are insoluble in water but soluble in non-polar organic solvents (ether, chloroform, benzene, acetone)

Answer 1

Lipids

Question 2

a general term that describes a heterogenous group of chemical compounds:

• fats
• oils
• waxes
• steroids
• derived lipids

Answer 2

Lipids

Question 3

general properties of lipids:

Answer 3

1- relatively insoluble in water
2- soluble in non polar solvents such as ether, chloroform, benzene, acetone.
3- stored in adipose tissue
4- serve as thermal insulator & electrical (in nerves)
5- lipoproteins are important in cells+they serve as transport in blood

Question 4

Lipids are important as a dietary constituents; due to:

Answer 4

1- high energy value
2- essential fatty acids
3- fat soluble vitamins [A D E K]

Question 5

lipids are classified as:

Answer 5

1- Simple:
~ waxes
~ triglycerides

2-Complex:
~ phospholipids
~ glycolipids

3-Derived:
~steroids
~prostaglandins

Question 6

an ester-containing lipid with just two types of components:

• an alcohol
• one or more fatty acids

Answer 6

Simple Lipids

Question 7

an ester-containing lipid with more than two components:

• an alcohol
• fatty acids
• plus others

Answer 7

Complex Lipids

Question 8

esters of fatty acids with glycerol (triacylglycerols)

Answer 8

Fats and oils

Question 9

esters of fatty acids with high molecular weights monohydric alcohol

Answer 9

Waxes

Question 10

lipids containing:

fatty acids + alcohol + phosphoric acid residue

Answer 10

Phospholipids

Question 11

lipids containing:

fatty acid + sphingosine(type of alcohol) + carbohydrate

Answer 11

Glycolipids

Question 12

this group includes:
1- cholesterol
2- steroid hormones
3- fatty aldehyde
4- fat soluble vitamin [A D E K]
5- some other alcohol

Answer 12

Derived Lipids

Question 13

• Biological molecules consists of a hydrophobic hydrocarbon chain with a terminal carboxyl group
• they function as the building blocks of lipids.

Answer 13

Fatty acids

Question 14

depending on the ….. group, the physical properties of fatty acids may vary.

Answer 14

R group (hydrocarbon chain)

Question 15

functions of fatty acids (6)

Answer 15

1- energy source: during fasting (or keto) blood level of FFA increases.

2- FAs can be oxidized by liver and muscle for energy.

3- structural components of membrane lipids

4-attached to some intracellular proteins

5-precursors of hormone-like prostaglandins

6- esterified TAG serve as major energy reserve in the body.

Question 16

FAs consists of 2 different groups that make them amphipathic:

Answer 16

• Hydrophobic hydrocarbon chain

- hydrophilic carboxyl group

Question 17

Fatty acids (FAs) can exist as ………… fatty acids:

• more than 90% is found in plasma
• triacylglycerols (triglycerides)
• cholesterol
• phospholipids

Answer 17

1-Esterified fatty acids

Question 18

Fatty acids (FAs) can exist as ............ fatty acids:
-are circulated in association with albumin.

Answer 18

2-Free Fatty Acid

Question 19

classification of FA :

depending on the length of the hydrocarbon chain

Answer 19

• short chain : 2-6 carbons
• medium chain: 8-14 carbons
• Long chains: 16-22 carbons
• Very long chains: 24+ carbons

Question 20

classification of FA :

depending on saturation of hydrocarbon chain

Answer 20

1- Saturated FA:no double bonds

2- Unsaturated FA: one or more double bonds.

Question 21

short chain saturated fatty acids have …….. melting point and are ……… at room temperatures

Answer 21

Low , liquid

Question 22

medium and long chain saturated fatty acids have …….. melting point and are ……… at room temperatures

Answer 22

high , solid

Question 23

unsaturated fatty acids are normally …….. at room temperatures, and their melting point is ……..

Answer 23

liquids , low

Question 24

addition of double bonds ……… the melting point , however , increasing the chain length …………. the melting point

Answer 24

decreases , increases

Question 25

the two polyunsaturated fatty acids that are essential fatty acids:

Answer 25

Linoleic acid (omega6)& Linolenic acid(omega3)

Question 26

the precursor of omega-6 arachidonic acid, the substrate for prostaglandin synthesis.

Answer 26

Linoleic acid

Question 27

clinical importance of omega-3 fatty acids:

Answer 27

1- prevent cardiac arrhythmias
2- act as anti-thrombotic agents
3- inhibit growth of atherosclerosis
4- acts as anti-inflammatory agent
5- Lower VLDL and increase HDL

Question 28

a triacylglycerol that is Solid at room temperature.

• from animal sources
• contain more saturated FA

Answer 28

Fat

Question 29

a triacylglycerol that is liquid at room temperature.

• from plant sources
• high content of unsaturated FA

Answer 29

Oil

Question 30

…… double bonds in unsaturated fatty acids leads to poor packing.

Answer 30

cis

Question 31

typical saturated fatty acids in are tightly packed together in …….. configuration.

Answer 31

Trans