BCH 201 Lipid Chemistry and Hemoglobin Flashcards
What are lipids?
Lipids are a class of biological molecules having low solubility in water and high solubility in nonpolar solvents (e.g. Benzene, chloroform, ether etc.)
Principal form of stored energy in most organisms and major constituents of cellular membranes.
Biological functions of lipids
- Storage form of energy: The fats and oils are used almost universally as stored forms of energy in living organisms.’
- Structural Lipids: Lipids are major structural components of membranes, e.g. phospholipids, glycolipids and sterols.
- Cholesterol, a sterol, is a precursor of many steroid hormones, vitamin D and is also an important component of plasma membrane.
4.Lipid acts as a thermal insulator in the subcutaneous tissues and around certain organs.
- Nonpolar lipids act as electrical insulators in neurons.
- Lipids are important dietary constituents because of the fat soluble vitamins and essential fatty acids which are present in the fat of natural foods
- Lipids help in absorption of fat soluble vitamins (A,D,E and K). They act as a solvent for the transport of fat soluble vitamins.
- Gives bodily shape
- Improves the taste of food
- Prostaglandin formation and role in inflammation
Classification of lipids based on chemical nature
- Simple lipids: Esters of fatty acids with glycerol or other higher alcohols eg. triglycerides and triacylglycerols
- Compound lipids: Esters of fatty acids with alcohol in addition to other groups.
-Phosphoric acid, = Phospholipids- Non-phosphorylated lipids and glycolipids
- Derived lipids: these are derived from lipids or precursors of lipids e.g. fatty acids and steroids.
Derived lipids are the substances derived from simple and compound lipids by hydrolysis. These includes fatty acids , alcohols , monoglycerides and diglycerides , steroids , terpenes, carotenoids - Lipids complexes to other compounds.
-e.g. Lipoproteins, proteolipids.
Discuss fatty acids
Fatty acids:
-major constituents of lipids in the body.
- carboxylic acids with hydrocarbon chains ranging from 4 to 36 carbons long (C4 to C36)
They can be saturated (contains no double bonds) unsaturated (contains one ore more double bonds)
Fatty acids are carboxylic acids with hydrocarbon chains (–CH2–CH2–CH2–) and represented by a chemical formula R-COOH, where R stands for hydrocarbon chain
COOH is the functional group
The physical properties of fatty acids varies depending on R group(hydrocarbon chain)
Fatty acids are amphipathic in nature, i.e. each has hydrophilic (COOH) and hydrophobic (hydrocarbon chain) groups in the structure.
The physical properties of fatty acids vary, depending on what?
The R group
Carbon atoms 2 and 3 are often referred to as what?
α and β respectively.
The methyl carbon atom at the distal end of the chain is called what?
omega Ѡ carbon
systems are used to designate the position of double bond?
C-system
Ѡ- or n-system.
The Ѡ system is usually used by who?
nutritionists
Examples of naturally occurring unsaturated FA, in Ѡ- or n-system.
Ѡ -9, Ѡ -6 and Ѡ -3 series. For example,
Ѡ-9 : Oleic acid (C:18:1 :Ѡ-9)
Ѡ-6 : Linoleic acid (C:18:2: Ѡ-6)
Arachidonic acid (C:20:4:Ѡ-6)
Ѡ -3 : Linolenic acid (C:18:3:Ѡ-3)
Why are FA’s poorly soluble in water?
The nonpolar hydrocarbon chain
The longer the fatty acyl chain, and the fewer the double bonds, the lower is the solubility.
What are Triacylglycerols?
Triacylglycerols are fatty acid esters of glycerol
1.They are the simplest lipids constructed from fatty acids, also called triglycerides, fats, or neutral fats
- Triacylglycerols are composed of three
fatty acids each in ester linkage with a single glycerol
3.Those containing the same kind of fatty acid in all three positions are called simple triacylglycerols.
What are glycerophospholipids?
A 1,2-diacylglycerol that has a phosphate group esterified at carbon atom 3 of the glycerol backbone is a glycerophospholipid, also known as a phosphoglyceride
One of the largest classes of natural lipids and one of the most important.
They are essential components of cell membranes - in small concentrations in other parts of the cell
All glycerophospholipids are members of the class known as phospholipids.
Phosphatidic acid
Phosphatidic acid, the parent compound for the glycerol-based phospholipids
-consists of glycerol-3-phosphate, with fatty acids esterified at the 1- and 2- positions
Phosphatidic acid is found in small amounts in most natural systems and is an important intermediate in the biosynthesis of the more common glycerophospholipids
What are phospholipids?
These are made up of fatty acid, glycerol or other alcohol, phosphoric acid and nitrogenous base.
Phospholipids are the major lipid constituents of cell membranes
Like fatty acids, phospholipids are amphipathic in nature, i.e. each has a hydrophilic or polar head (phosphate group) and a long hydrophobic tail (containing two fatty acid chains)
