Lipids

Lipids are organic molecules composed of long hydrocarbon chains, and they are non-polar.

Uses:


 * Insulating and protecting vital organs
 * Forming the cell membrane
 * Energy storage

There are three kinds of lipids:


 * Triglycerides (Fats and oils)
 * Phospholipids (Lecithin)
 * Steroid (Cholesterol)

Triglycerides:


 * Formed from a condensation reaction between Propane-1, 2, 3-triol (glycerol) and a long carboxylic acid chain (fatty acids)


 * They can be present in to different forms
 * Fats (solid): Saturated carboxylic groups that contain no C=C
 * Oils (liquid): Unsaturated and posses at least one C=C

Phospholipid:


 * Integral part of the cell membrane[[image:fdrsummerdrugs/Lecithin (1).gif align="right"]]
 * It has fourcomponents:
 * Fatty acid
 * Glycerol
 * Phosphate group
 * Nitrogen containing alcohol

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 * <span style="font-family: Arial,Helvetica,sans-serif;">Propane-1, 2, 3-triol (glycerol) is bonded to the phosphate group by esterification; the phosphate group is bonded to the nitrogen containing alcohol by condensation.
 * <span style="font-family: Arial,Helvetica,sans-serif;">Composed of a non-polar body, but with a polar head. This allows for the formation of the cell membranes phospholipid bilayer, having the heads in teh outer-most and inner-most side and the tails in the inside of the membrane.

<span style="font-family: Arial,Helvetica,sans-serif;">Cholesterol:


 * <span style="font-family: Arial,Helvetica,sans-serif;">It is a steroid do to the four ring structure it contains.


 * <span style="font-family: Arial,Helvetica,sans-serif;">It is transported by lipoproteins


 * <span style="font-family: Arial,Helvetica,sans-serif;">Lipoproteins:
 * Low density lipoprotein (LDL)
 * Have a size of 18-25 nm
 * These proteins can transport cholesterol through the arteries
 * Cholesterol can stick to walls or the arteries and cause cardiovascular diseases
 * Main source of is saturated fats that can come from lauric (C12), myristic (C14), palmitic (C16) acid
 * High density lipoproteins (HDL)
 * Have a size of 8-11 nm
 * These can remove the cholesterol from that arteries and return them to the liver where the lipids are used to store energy

<span style="font-family: Arial,Helvetica,sans-serif;">What are fatty acids?


 * <span style="font-family: Arial,Helvetica,sans-serif;">There are many different types of fatty acids two of which are: Stearic acid with a melting point of 69.6 ˚C and Linoleic acid with a melting point of -5.0 ˚C. Both have the same number of carbon atoms and have a similar molar mass but the Linoleic acid contain C=C


 * <span style="font-family: Arial,Helvetica,sans-serif;">They have a tetrahedral form, this allows for greater surface area andstronger Van der Waals.


 * <span style="font-family: Arial,Helvetica,sans-serif;">C=C disrupts the tetrahedral arrangement and decreases Van de Waals


 * <span style="font-family: Arial,Helvetica,sans-serif;">This causes the lower melting point that is seen in the unsaturated fatty acids (oils)


 * <span style="font-family: Arial,Helvetica,sans-serif;">There are certain types of fatty acids that cannot be synthesized by the human body, they are called essential fatty acids


 * <span style="font-family: Arial,Helvetica,sans-serif;">Mostly fats are a mixture of three different components: saturated, mono-unsaturated and poly-unsaturated fatty acids


 * <span style="font-family: Arial,Helvetica,sans-serif;">An example of an essential fatty acid is:
 * <span style="font-family: Arial,Helvetica,sans-serif;">ω-3 and ω-6 fatty acid
 * <span style="font-family: Arial,Helvetica,sans-serif;">ω-3 can be found in seeds while ω-6 can be found in vegetable oils
 * <span style="font-family: Arial,Helvetica,sans-serif;">ω-3 would be a fatty acid where one of the double bonds is found in the third carbon.
 * <span style="font-family: Arial,Helvetica,sans-serif;">ω-6 would be a fatty acid where one of the double bonds is found in the sixth carbon.

<span style="font-family: Arial,Helvetica,sans-serif;">Synthetically made fatty acids:


 * <span style="font-family: Arial,Helvetica,sans-serif;">Made by partially hydrogenating polyunsaturated fatty acids, forming a r**trans-isomer**
 * <span style="font-family: Arial,Helvetica,sans-serif;">Can be found in fried food

<span style="font-family: Arial,Helvetica,sans-serif;">Hydrolysis of fats:


 * <span style="font-family: Arial,Helvetica,sans-serif;">Lipids are hydrolyzed by **lipas****e** to form glycerol and fatty acids
 * <span style="font-family: Arial,Helvetica,sans-serif;">Glycerol and fatty acids are then broken down by redox reactions for energy
 * <span style="font-family: Arial,Helvetica,sans-serif;">End result is carbon dioxide and water

<span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;">Determining the number of C=C bonds in an unsaturated fats:


 * <span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;">Unsaturated fats can perform addition reactions
 * <span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;">Adding **Iodine** to the a unsaturated fat would allow to determine the number of C=C bonds.
 * <span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;">The reason this works is because, for example, 1 mole of Iodine will react with 1 mole of C=C
 * The purple color of Iodine will encompass all of the fat as the reaction occurs

The roles of lipids in the body:


 * <span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;">Energy storage as they are less oxidized than carbohydrates
 * <span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;">Insulation and protection of organs. They are stored in a tissue called **adipose** allows for this function as lipids are shock absorbers
 * <span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;">Steroid hormones: testosterone and progesterone
 * <span style="font-family: Arial,Helvetica,sans-serif; line-height: 1.5;"> Cell membrane