Lipids Flashcards
What are the 3 components of a lipid
A lipid is similar to a Carbohydrate it contains:
- carbon
- hydrogen
- oxygen
However the proportion of oxygen is less than carbohydrates
what is the proportions of oxygen and carbon
they contain much less oxygen
What are the 4 things I need to know
- How Ts are formed
- Difference between saturated and unsaturated fatty acids
- Function of lipids
- Role of saturated fats in disease
What is a lipid
Large a varied group of organic compounds e.g. fats and oils
How is a trygliceride formed
- They are formed as a result of 3 Condensation reactions involving
- the OH group of Glycerol
- and the COOH group of each fatty acid
- For each condensation reaction an ester bond is formed
What happens when tryglicerides are oxidised
They release energy to be used in respiration
When tryglicerides are oxidised do they release more or less energy than carbohydrate
Release more energy than CH2O of equal mass
What is an ester bond
A bond between glycerol and fatty acids in lipids which occurs between an oxygen molecle and a carbon molecule
What are the two types of fatty acids
- Saturated fatty acids
- Unsaturated fatty acids
What is the difference between saturated and unsaturated fatty acids
- Saturated fatty acid
- Single carbon to cabon bonds (C-C)
- Unsaturated fatty acids
- Double carbon to carbon bonds (C=C)
What is a fatty acid
An organic acid with a carboxyl (COOH) group at one end, which has a long hydrocarbon tail (R group) attached
What is the general formula of a fatty acid
RCOOH
What determines the properties of any particular lipid
- They glycerol molecule in a lipid always stays the same
- The fatty acids determine the properties of the lipid
How do the fatty acids in a lipid vary
- Length of the hydrocarbon tail
- HOw saturated the R group is
What is the difference between a trygliceride and a phospholipid in terms of chemical structure
- Tryglicerides
- 3 fatty acid chains
- Insoluable in water
- Phospholipid
- 2 fatty acid chains and a phosphate group
- Lipid element is non polar, and therefore non soluable in water (Hydrophobic)
- Phosphate group is polar and therefore soluable in water (Hydrophilic)
What happens when a phospho lipid comes into contact with water
- Hydrophilic heads are attracted to water and dip into it
- The hydrophobic tails move away from the water
- This forms a mono layer
What is hydrophobic
Fear of water
Hydrophilic
Love of water
What 2 things happen if you shake up this mono layer
- Phospholipids would form tiny spherical structures called micelles
- The hydrophobic tails turn inwards and are protected by the hydrophilic head
Draw the chemical structure of a phospholipid
What is a wax
Waxes are similar to fats and oils
However their long chain fatty acids are linked to a long chained alcohol.
What are the properties of wax
- Melt above 450C
- Insoluable to water and forms waterproof layers over some cells
- Which stops water getting in and water getting out
What 2 examples might you use to illustrate the role of wax?
- Insects have a waxy cuticle which helps to reduce water loss
- Similarly leaves have a waxy cuticle to help reduce transpiration
What is a steroid
- A steroid is an organic compound
- has a 4 ring structure with various side chains
- e.g. Dietry lipid cholesterol
- Sex hormones estradiol and testosterone
What are the properties of a steroid
- 4 ring structure with various side chains
- Insoluable in water
- Soluable in organic solvents
- Human steroids are synthesised from cholesterol
What is the importance of steroids
They are of great importance in humans e.g. hormones oestrogen, progesterone and testerone and involved in the cells e.g. cell membrane.
What is the test for fats and oils
Emulsion test
What are the 4 steps for the emulsion test
- Add extract to a clean test tube
- Add pure ethanol
- Shake to dissolve any lipid in the extract
- Add equal amount of water to the mixture and shake
What are the 2 results of the emulsion test
- The mixture white as an emulsion if lipid is present
- The mixture remains clear if no lipid is present
What state of matter are saturated fats at room temperature
Solid, because…
All the carbon atoms are linked to the maximum nos of hydrogen atoms
So the fatty acid is straight which means the molecules can align readily
What state of matter are unsaturated fats at rooms temperature
- Liquid, because…
- If any carbon to carbon bond is not a single bond, the chain gets a kink in it
- Which means that the molecules cannot align uniformerly which means that the lipid cannot align uniformerly
What are the 2 roles of phospholipid
- Found in biological cell membranes
- Electrical insulation - The myelin sheeth which surrounds the axon of nerve cells
What are the 4 roles of tryglicerides
- Energy reserve in both animals and plants
- Thermal insulation - When stored under the skin lipids insulate against head loss or heat gain when its hot e.g. Camel humps
- Protection - Fat is often stored around vital organis e.g. Kidney to protect against physical damage
- Formation of metabolic water - Water is released during chemical reactions in the body especially when tryglicerides are oxidised
What is the role of wax (main function)
- Waterproofing
- Insects have a waxy cuticle which helps to reduce water loss
- PLANTS have a waxy cuticle to help reduce transpiration
What are 4 risks of heart disease
- Smoking
- Diets which are high in saturated fats
- Lack of exercise
- Aging
What is the aetiology of heart disease
What is the cause of heart disease
- Patients suffering from risk factors e.g. smoking start to suffer from arterioscelrosis
- The arteries start to thicken and harden, the lumen of the artery starts to narrow and the patient gets hypertension
- Inappropriate diet ( saturated fats increased LDL) leads to atherosclerosis where plaques of fat (Atheroma) are deposited in the arterial wall narrowing the artery until the point where it blocks.
- If the artery blocks completely the patient has a heart attack
What is the difference between LDL and HDL
HDL cholesterol is described as good cholesterol and is produced when the patient has high levels of unsaturated fats. It can have a positive effect on health.
LDL cholesterol is described as bad cholesterol and occurs when the patient has high levels of saturated fats, often contributing to the growth of atheroma and atherosclerosis which can be life threatening.
What is the name given to a vein which gets blocked in the leg
Deep vein thrombosis
What happens if a clot breaks off and travels to the brain and blocks one of the arteries there
Patient suffers from a stroke
What is the name given to a clot which blocks the lungs
Pulmonary embolism
