What do you use fats for? All around your body? lipids What do you use fats for? All around your body?

Basic Structure All lipids contain three elements Carbon, Oxygen and Hydrogen They are known as neutral fats as they have mostly uncharged and are hydrophobic so do not readily dissolve in water Essentially it is a massive ester (remember these from GCSE chemistry?) Who can remember the ester bond?

Structure and formation

Fatty acid Really long carboxylic acid general structure Cn H2n+1 COOH Draw one with 5 carbons Do one saturated one unsaturated

More gubbins Ones without double bonds are called – saturated – solid at room temperature due to H-bonds Ones with some double bonds are called – unsaturated – liquid at room temperature – less H-bonding Really useful as energy storage as they are reduced (lots of hydrogen) and anhydrous they store a lot of energy in them there bonds And once you chop off all the hydrogens what do you make – water! This is why camels store fat They bond with Glycerol in a process called esterification

Structural formula Look at the shape The kinks in the unsaturated explains why unsaturated fats are liquids The un straight chain prevents the chains lining up to do H-bonds

Formation All you need is one Glycerol and some fatty acids The process is called ESTERIFICATION and is a Condensation Reaction The reverse is a Hydrolysis reaction The product with a Glycerol molecule is a Tri, Bi or mono glyceride (dependent of how many fatty acids we have) Glycerol is C3H8O3

Uses of Fats On white boards how many uses of Fats can you think of Did you get: Energy Source – remember they are stored in adipose tissue and are insoluble so do not affect osmotic pressure Membranes Waxes and Oils for waterproofing in plants and animals Protection from cold (insulating) and shock (impact) Source of metabolic water

So that is big lipids Now for ickle lipids can you think of any? I give you Phospholipids Cholesterol What can you tell me about them?

Phospholipids Special di-glyceride molecules (two chains) They are made from one phosphate group, glycerol and two fatty acid chains The phosphate end is the hydrophilic end and the other is hydrophobic The Hydrophobic ends attract to form a bi layer They are amphipathic which means they are hydrophilic and hydrophobic

Structural formula

Cholesterol The most misunderstood of all fats Is it bad? Or is it vital to your survival? Decide and explain

Structure A type of sterol lipid – has the same structure as most steroids 3 hexose carbon rings One pentose carbon ring Carbon chain Hydroxyl group – Hydrophilic Helps provide structure to the membrane

Higher or Lower The thing with cholesterol is they are seen as bad When I was your age they told us to not eat eggs – full of cholesterol There are different types molecules called lipoproteins in your body – and your body makes both their job is to move cholesterol on High density is good Low density is bad – this causes blockages

Questions What are the main components of a triglyceride and what bonds hold them together? Why do lipids have a hi energy content? Describe esterification What are the products of hydrolysis of a triglyceride? What are the biological roles of lipids Suggest hoe the structure of the membrane of an arctic fish may differ from a tropical fish How does cholesterols structure allow it to perform it’s role in cell membranes?