UNIT 2.3

Non-polar hydrophilic molecules, non-soluable in water but soluble in non-polar organic solvent Function: Chemical Composition (name bond): 1 glycerol + 2 fatty acids + phosphate group for phospholipids Functions (6): 1) Storage of energy 2) Structural Role 3) Long Term energy storage molecules 4) Hormonal Role, signalling molecule 5) Thermal Insulation 6) Protection of organs Structure: Contains repeating units of fatty acids, 2 or 3 hydrocarbon chains or the quadruple ring structure of steroids Types (3): Simple: ester of fatty acids and alcohol Compound: ester of fatty acids and alcohol an additional groups Derived: substances derived from simple or compound lipids

Simple lipid Function: Storage of energy Structure: 3 fatty acids + 1 glycerol * Hydroxyl group (glycerol) combine with carboxyl (fatty acids) = ester linkage * Forms 3 water molecues Example: fats and oils

Compound lipids Function: Structural role Structure: 2 fatty acids + phosphate group + glycerol

Derived Lipids Function: Hormonal roles, signalling molecule Structure: 4 fused rings in their molecule Example: Cholesterol, progesterone, estrogen and testosterone

Structure: 1) Long hydrocarbon chains found in triglycerides and phospholipids 2) Carboxyl group at the end of the chain makes the fatty acid 3) Unbeanched hydrocarbon chain 4) Mathyl group at the opposite

1) Double bonds in the hydrocarbon chain 2) Originates from animals (fats) 3) Generally solid at room temperature (animal fat)

1) No double bond (mono = 1, poly = many) 2) Originates from plants (oils) 3) Generally liquid at room temperature (plant oils)

Hydrogen bonds: attached when carbon is attached on the same side Bond: Double bond causes a bend Health: good Packed: loosely pack Melting Point: Low

Hydrogen Bonds: attache to the carbon on different sides Bond: double bonds do not cause bend Health: bad Packed: closely packed Melting Point: High

Fats and cholesterol do not dissolve in blood, they are constantly packaged with proteins (form lipoproteins) for transport Carry cholesterol from the liver to the rest of the body Scavenge excess cholesterol and carry it back to the liver for disposal Saturated fats + Trans fats –> increase LDL + decrease HDL –> raise blood cholesterol levels Cis Unsaturated fats –> increase HDL –> lower blood cholesterol levels

High cholesterol levels in the bloodstream –> hardening + narrowing of arteries –> atherosclerosis High levels of LDL in the bloodstream –> form deposits in the walls of the arteries Accumulation of fat in arterial walls leads to the development of plaques that restrict blood flow If coronary arteries are blocked –> coronary heart disease = heart attack

1) Diets rich in saturated fats + trans fats –> increase the risk of CHD 2) Diets rich in monosaturated + polyunsaturated cis fats –> decrease risks of CHD

1) A positive correlation has been found between the intake of saturated fats and the incidence of CHD in human populations Counter: certain populations do not fit this trend (Maasai tried in Africa, rich fat diet but low rates of CHD) 2) Intervention studies have shown that lowering dietary intakes of saturated fats reduces development of CHD (high blood pressures, cholesterol levels) Counter: validity of intervention studies is dependent on the size of composition of the cohort, as well as duration of study 3) In patients who died from CHD, fatty deposits in diseased arteries found to contain high concentrations of trans fats Counter: Genetic factors may play a role

Proportion of saturated and trans fats in Western diets has decreased over the last 50 years but the incidence of CHD has risen Counter: Increased carbohydrate intake can cause detrimental health effects associated with CHD (diabetes, obesity) Counter: Incidence of CHD dependent of a myriad of factors besides dietary intake (eg. exercise, access to health care)

S - torage O - smolarity D - igestion A - TP yield S - solubility

1) Amount of energy released in cell respiration per gram is double for the carbohydrate release 2) Lipids just 1/6 as much as body mass as carbohydrates 3) Fats are stored as pire droplets 4) 1g of glycogen is stored associated with 2 g of water, critical for active animal since they have to carry a lot of weight

Used as a screening tool to identify possible weight problems, however, BMI is not a diagnostic tool BMI = Mass in Kilograms / (Height in metres )^2 (units are in kgm -2) Below 18.5 –> Underweight 18.5 - 24.9 –> Normal 25.0 - 29.9 –> Overweight 30.0 - Above –> Obese

Food supplies are insufficient or unevenly distributed The cause of being underweight is Anorexia Nervosa

Psychological condition that involves voluntary starvation and loss of body mass

Increases risk of conditions such as CHD and Diabetes type II Reduces life expectancy significantly Increases overall cost of healthcare in countries where rates of obesity are rising

Display height and weight on perpendicular axes