11-Chemistry of Lipids(fatty acids) Flashcards
biological molecules that are insoluble in water but soluble in non-polar organic solvents (ether, chloroform, benzene, acetone)
Lipids
a general term that describes a heterogenous group of chemical compounds:
- fats
- oils
- waxes
- steroids
- derived lipids
Lipids
general properties of lipids:
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
Lipids are important as a dietary constituents; due to:
1- high energy value
2- essential fatty acids
3- fat soluble vitamins [A D E K]
lipids are classified as:
1- Simple: ~ waxes~ triglycerides
2-Complex:~ phospholipids~ glycolipids
3-Derived:~steroids~prostaglandins
an ester-containing lipid with just two types of components:
- an alcohol
- one or more fatty acids
Simple Lipids
an ester-containing lipid with more than two components:
- an alcohol
- fatty acids
- plus others
Complex Lipids
esters of fatty acids with glycerol (triacylglycerols)
Fats and oils
esters of fatty acids with high molecular weights monohydric alcohol
Waxes
lipids containing:
fatty acids + alcohol + phosphoric acid residue
Phospholipids
lipids containing:
fatty acid + sphingosine(type of alcohol) + carbohydrate
Glycolipids
this group includes: 1- cholesterol 2- steroid hormones 3- fatty aldehyde 4- fat soluble vitamin [A D E K] 5- some other alcohol
Derived Lipids
- Biological molecules consists of a hydrophobic hydrocarbon chain with a terminal carboxyl group
- they function as the building blocks of lipids.
Fatty acids
depending on the ….. group, the physical properties of fatty acids may vary.
R group (hydrocarbon chain)
functions of fatty acids (6)
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.
FAs consists of 2 different groups that make them amphipathic:
- Hydrophobic hydrocarbon chain
- hydrophilic carboxyl group
Fatty acids (FAs) can exist as ………… fatty acids:
- more than 90% is found in plasma
- triacylglycerols (triglycerides)
- cholesterol
- phospholipids
1-Esterified fatty acids
Fatty acids (FAs) can exist as ............ fatty acids: -are circulated in association with albumin.
2-Free Fatty Acid
classification of FA :
depending on the length of the hydrocarbon chain
- short chain : 2-6 carbons
- medium chain: 8-14 carbons
- Long chains: 16-22 carbons
- Very long chains: 24+ carbons
classification of FA :
depending on saturation of hydrocarbon chain
1- Saturated FA:no double bonds
2- Unsaturated FA: one or more double bonds.
short chain saturated fatty acids have …….. melting point and are ……… at room temperatures
Low , liquid
medium and long chain saturated fatty acids have …….. melting point and are ……… at room temperatures
high , solid
unsaturated fatty acids are normally …….. at room temperatures, and their melting point is ……..
liquids , low
addition of double bonds ……… the melting point , however , increasing the chain length …………. the melting point
decreases , increases
the two polyunsaturated fatty acids that are essential fatty acids:
Linoleic acid (omega6)& Linolenic acid(omega3)
the precursor of omega-6 arachidonic acid, the substrate for prostaglandin synthesis.
Linoleic acid
clinical importance of omega-3 fatty acids:
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
a triacylglycerol that is Solid at room temperature.
- from animal sources
- contain more saturated FA
Fat
a triacylglycerol that is liquid at room temperature.
- from plant sources
- high content of unsaturated FA
Oil
…… double bonds in unsaturated fatty acids leads to poor packing.
cis
typical saturated fatty acids in are tightly packed together in …….. configuration.
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