▪️🔹1.1 Lipids -Chemical Elements Flashcards
What do lipids contain?
Carbon, hydrogen and oxygen, less oxygen than carbon and hydrogen (in proportion)
What makes lipids insoluble in water
What do lipids dissolve in?
The fact they are non-polar compounds
They dissolve in organic solvents such as propanone and alcohols
What from triglycerides?
Combination of one glycerol molecule (stays the same) and three fatty acid molecules (these component can vary)
How to the fatty acids joint to glycerol?
By condensation reactions where 3 molecules of water are removed and water bonds are formed between the glycerol and fatty acids
Describe why phospholipids have one end soluble and one end insoluble
-One end of a phospholipid has lots of oxygen atoms which interacts with water and is hydrophilic (polar head of the molecule)
-fatty acid tails do not have any oxygen atoms and don’t interact with water so they are hydrophobic (non-polar)
(LOOK AT DIAGRAM)
What are waxed?
What temperature do waxed melt at?
Waxes are lipids that melt above 45 degrees
Name a role of waxes
Waterproofing role In animals (insect exoskeleton) and the leafs outer cuticle
What makes a fatty acid saturated?
When the hydrocarbon chain has only single carbon-carbon bonds
When is a fatty acid unsaturated
What does this cause
When any of the carbon-carbon bonds is not a single bond
This causes a kink in the fatty acid chain
What does the kink in a fatty acid chain cause
Causes the molecules to not align uniformly, meaning the lipid does not solidify :: unsaturated lipids are oils
What are plant lipids usually?
Usually unsaturated e.g olive oil and sunflower oil
What does mono-unsaturated mean?
What does polyunsaturated mean?
There is one carbon-carbon double bond (mono)
There are many carbon-carbon double bonds (poly)
Name the roles of phospholipids
- biological membranes
- electrical insulation (around nerve cells)
Name the roles of triglycerides
- energy reserves in both plants and animals
- thermal insulation (stored under the skin to insulate against heat loss in cold or heat gain when hot)
- protection (fats stored around delicate organs such as kidneys, protecting against damage)
- metabolic water (water released during chemical reactions in the body)
Name a test to identify fats and oils
The emulsion test,
Add ethanol to a sample (dissolves lipids) and shake with equal volume of water
They form a cloudy white emulsion
Name the 2 main causes of heart disease
- fatty deposits in the coronary arteries (artherosclerosis)
- High blood pressure (hypertension)
What happens when food has been absorbed into the small intestine?
Lipids and proteins combine to make lipoproteins which travel around the body in the blood stream
What happens if a persons diet is high in saturated fats?
Low density lipoproteins (LDL) build up as atheroma in the coronary arteries, restricting blood flow and oxygen delivery to the heart, if the vessel is completely blocked a heart attack occurs
What happens if a persons diet has a high proportion of unsaturated fats?
The body makes more Hugh density lipoprotein (HDL) which carries harmful fats away to the liver for disposal.
The higher the HDL:LDL in a persons blood the lower the risk of cardio-vascular disease
Suggest why plants store energy as lipids
- lipids contain twice as much energy as carbohydrates
- lipids are osmotically inert :: don’t effect the water potential of cells
Through which part of the membrane would a lipid soluble molecule pass?
Through the lipid tail of phospholipids in the bilayer
