Lipids

Question 1

What are the 3 components of a lipid

Answer 1

A lipid is similar to a Carbohydrate it contains:

1. carbon
2. hydrogen
3. oxygen

However the proportion of oxygen is less than carbohydrates

Question 2

what is the proportions of oxygen and carbon

Answer 2

they contain much less oxygen

Question 3

What are the 4 things I need to know

Answer 3

1. How Ts are formed
2. Difference between saturated and unsaturated fatty acids
3. Function of lipids
4. Role of saturated fats in disease

Question 4

What is a lipid

Answer 4

Large a varied group of organic compounds e.g. fats and oils

Question 5

How is a trygliceride formed

Answer 5

• 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

Question 6

What happens when tryglicerides are oxidised

Answer 6

They release energy to be used in respiration

Question 7

When tryglicerides are oxidised do they release more or less energy than carbohydrate

Answer 7

Release more energy than CH₂O of equal mass

Question 8

What is an ester bond

Answer 8

A bond between glycerol and fatty acids in lipids which occurs between an oxygen molecle and a carbon molecule

Question 9

What are the two types of fatty acids

Answer 9

1. Saturated fatty acids
2. Unsaturated fatty acids

Question 10

What is the difference between saturated and unsaturated fatty acids

Answer 10

1. Saturated fatty acid
   
   • Single carbon to cabon bonds (C-C)
2. Unsaturated fatty acids
   
   • Double carbon to carbon bonds (C=C)

Question 11

What is a fatty acid

Answer 11

An organic acid with a carboxyl (COOH) group at one end, which has a long hydrocarbon tail (R group) attached

Question 12

What is the general formula of a fatty acid

Answer 12

RCOOH

Question 13

What determines the properties of any particular lipid

Answer 13

1. They glycerol molecule in a lipid always stays the same
2. The fatty acids determine the properties of the lipid

Question 14

How do the fatty acids in a lipid vary

Answer 14

1. Length of the hydrocarbon tail
2. HOw saturated the R group is

Question 15

What is the difference between a trygliceride and a phospholipid in terms of chemical structure

Answer 15

• 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)

Question 16

What happens when a phospho lipid comes into contact with water

Answer 16

• Hydrophilic heads are attracted to water and dip into it
• The hydrophobic tails move away from the water
• This forms a mono layer

Question 17

What is hydrophobic

Answer 17

Fear of water

Question 18

Hydrophilic

Answer 18

Love of water

Question 19

What 2 things happen if you shake up this mono layer

Answer 19

1. Phospholipids would form tiny spherical structures called micelles
2. The hydrophobic tails turn inwards and are protected by the hydrophilic head

Question 20

Draw the chemical structure of a phospholipid

Question 21

What is a wax

Answer 21

Waxes are similar to fats and oils

However their long chain fatty acids are linked to a long chained alcohol.

Question 22

What are the properties of wax

Answer 22

1. Melt above 45⁰C
2. Insoluable to water and forms waterproof layers over some cells
   
   • Which stops water getting in and water getting out

Question 23

What 2 examples might you use to illustrate the role of wax?

Answer 23

1. Insects have a waxy cuticle which helps to reduce water loss
2. Similarly leaves have a waxy cuticle to help reduce transpiration

Question 25

What is a steroid

Answer 25

* 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

Question 26

What are the properties of a steroid

Answer 26

1. 4 ring structure with various side chains 2. Insoluable in water 3. Soluable in organic solvents 4. Human steroids are synthesised from cholesterol

Question 27

What is the importance of steroids

Answer 27

They are of great importance in humans e.g. hormones oestrogen, progesterone and testerone and involved in the cells e.g. cell membrane.

Question 28

What is the test for fats and oils

Answer 28

Emulsion test

Question 29

What are the 4 steps for the emulsion test

Answer 29

1. Add extract to a clean test tube 2. Add pure ethanol 3. Shake to dissolve any lipid in the extract 4. Add equal amount of water to the mixture and shake

Question 30

What are the 2 results of the emulsion test

Answer 30

1. The mixture white as an emulsion if lipid is present 2. The mixture remains clear if no lipid is present

Question 31

What state of matter are saturated fats at room temperature

Answer 31

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

Question 32

What state of matter are unsaturated fats at rooms temperature

Answer 32

* 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

Question 33

What are the 2 roles of phospholipid

Answer 33

1. Found in biological cell membranes 2. Electrical insulation - The myelin sheeth which surrounds the axon of nerve cells

Question 34

What are the 4 roles of tryglicerides

Answer 34

1. Energy reserve in both animals and plants 2. Thermal insulation - When stored under the skin lipids insulate against head loss or heat gain when its hot e.g. Camel humps 3. Protection - Fat is often stored around vital organis e.g. Kidney to protect against physical damage 4. Formation of metabolic water - Water is released during chemical reactions in the body especially when tryglicerides are oxidised

Question 35

What is the role of wax (main function)

Answer 35

* Waterproofing * Insects have a waxy cuticle which helps to reduce water loss * PLANTS have a waxy cuticle to help reduce transpiration

Question 36

What are 4 risks of heart disease

Answer 36

* Smoking * Diets which are high in saturated fats * Lack of exercise * Aging

Question 37

What is the aetiology of heart disease What is the cause of heart disease

Answer 37

1. Patients suffering from risk factors e.g. smoking start to suffer from **arterio**scelrosis 2. The arteries start to thicken and harden, the lumen of the artery starts to narrow and the patient gets hypertension 3. Inappropriate diet ( saturated fats increased LDL) leads to **athero**sclerosis where plaques of fat (Atheroma) are deposited in the arterial wall narrowing the artery until the point where it blocks. 4. If the artery blocks completely the patient has a heart attack

Question 38

What is the difference between LDL and HDL

Answer 38

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.

Question 39

What is the name given to a vein which gets blocked in the leg

Answer 39

Deep vein thrombosis

Question 40

What happens if a clot breaks off and travels to the brain and blocks one of the arteries there

Answer 40

Patient suffers from a stroke

Question 41

What is the name given to a clot which blocks the lungs

Answer 41

Pulmonary embolism