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.
Trans