(OPLAS) OPEN PROGRAM OF LEARNING AND ASSISTING STUDENTS BIOCHEMISTRY LIPIDS

Lipids Introduction to Lipids Structure of Lipids Lipids are water insoluble organic compound which can be extracted from the cells of organic solvent Lipids are formed by condensation reaction between fatty acid and glycerol 9alcohol) contain hydrocyl group (OH).

Cont….. Structure of Lipids Lipids occur into two from of fat and oil, fat are solid at room temperature and oil are liquid at room temperature. Fat and oil contain carbon, hydrogen and oxygen but has much smaller proportion of oxygen than that of carbohydrates

Cont…. Fatty acid contain the acidic group –COOH and they have formula R – COOH where R is alklyl group. Most of the time the natural occurring fatty acid have even number of carbon between 14 – 22 and the most commonly 16 or 18. This is the long chain of carbon is R – group forms a hydrocarbon tail because it’s a long chain of carbon and hydrogen only The hydrocarbon tail is called hydrophobic tail, (hydrophobic means wate hate) and hydrocarbon tail determine the characteristics of fatty acid . www.oplas.co.tz

Saturated and Unsaturated fats Unsaturated fats have at least one double bond in one of the fatty acids. A double bond happens when four electrons are shared or exchanged in a bond. They are much stronger than single bonds with only two electrons. Saturated fats have no double bonds. Fats have a lot of energy stored up in their molecular bonds. That's why the human body stores fat as an energy source. When you have extra sugars in your system, your body converts them into fats. When it needs extra fuel, your body breaks down the fat and uses the energy. Where one molecule of sugar only gives a small amount of energy, a fat molecule gives off many times more. www.oplas.co.tz

Components of Lipids Phospholipid The structure of the phospholipid molecule generally consists of hydrophobic tails and a hydrophilic head. Biological membranes in eukaryotes also contain another class of lipid, sterol, interspersed among the phospholipids and together they provide membrane fluidity and mechanical strength. Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline.  

Glycolipids Glycolipids are lipids with a carbohydrate attached. Their role is to provide energy and also serve as markers for cellular recognition. They occur where a carbohydrate chain is associated with phospholipids on the exoplasmic surface of the cell membrane. The carbohydrates are found on the outer surface of all eukaryotic cell membranes. The carbohydrate structure of the glycolipid is controlled by the glycosyltransferases that add the lipids and glycosylhydrolases that modify the glycan after addition.

Glycolipids structure cont…. Glycolipids structure They extend from the phospholipid bilayer into the aqueous environment outside the cell where it acts as a recognition site for specific chemicals as well as helping to maintain the stability of the membrane and attaching cells to one another to form tissues.

Triglycerides Fat is also known as a triglyceride. It is made up of a molecule known as glycerol that is connected to one, two, or three fatty acids. Glycerol is the basis of all fats and is made up of a three- carbon chain that connects the fatty acids together. A fatty acid is just a long chain of carbon atoms connected to each other.

Properties of Triglycerides Triglycerides are common lipids in nature and are classified as fat and oil. Fat are solid at room temperature and oil are liquid at room temperature . The higher the unsaturated condition of fatty acid, the higher the lipids formation also triglyceride are non polar so they do not dissolve in water due to presence of three hydrophoci tail and absence of OH group in glycerol and also triglyceride are lees denser than water and therefore float

Functions of Lipids 1. Lipids as an Energy Reserve: all of the energy needed by the human body is provided by the oxidation of carbohydrates and lipids. Whereas carbohydrates provide a readily available source of energy, lipids function primarily as an energy reserve. The amount of lipids stored as an energy reserve far exceeds the energy stored as glycogen since the human body is simply not capable of storing as much glycogen compared to lipids. 2. Lipids or fats are stored in cells throughout the body principle in special kinds of connective tissue called adipose tissue or depot fat. Whereas many cells contain phospholipids in the bilayer cell membranes, adipose tissue cells consist of fat globules of triglycerides which may occupy as much as 90% of the cell volume.

cont… 3. Lipids ingested as food are digested in the small intestine where bile salts are used to emulsify them and pancreatic lipase hydrolyzes lipids into fatty acids, glycerol, soaps, or mono- and diglycerides. There is still some dispute about the lipid form that passes through the intestinal wall -- whether as fatty acids or as glycerides. In either case, triglycerides are found in the lymph system and the blood

The End About Lipids