Lipids (2.1.1)

What are lipid molecules made from?
Carbon, hydrogen and a lower proportion of oxygen.
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What do lipids include?
Fatty acids, triglycerides and cholesterol.
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What is a fat?
A solid lipid at room temperature.
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What is an oil?
A liquid lipid at room temperature.
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What are the functions of lipids in living organisms?
Structural use- in cell membranes. Can be respired to release ATP energy. Stored in special cells which make up adipose tissue. Insulation, found underneath surface of skin. Some hormones are made of lipids. Protection around vital organs.
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What is a triglyceride made up of?
One molecule of glycerol attached to three fatty acids. The glycerol molecule always has the same structure.
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What is the structure of a glycerol molecule?
Three carbons, with an OH group attached to each, then the rest hydrogen.
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What does the fatty acid look like?
A hydrocarbon chain with an acid group at one end.
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What is an unsaturated hydrocarbon chain?
Where there are any C=C double bonds in the chain.
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What does introducing a C=C bond do to the hydrocarbon chain?
It causes the chain to bend, so the three chains wouldn't pack together as tightly, making the resulting lipid more fluid. Unsaturated fatty acids tend to be oils.
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What does monosaturated mean?
Contains one C=C bond.
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What does polysaturated mean?
Contains more than one C=C bond.
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What does hydrophobic mean?
The molecules aren't soluble in water. This is because lipids are non-polar. Triglycerides are hydrophobic.
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Describe the formation of a triglyceride.
The OH groups on the glycerol line up next to the OH group on the 3 fatty acids. Water molecules are then lost in a condensation reaction.
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Describe the phosphate head of a phospholipid.
Hydrophilic- water soluble. Due to the fact that it's polar.
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Describe the fatty acid tail of a phospholipid.
Hydrophobic- not soluble in water. Due to the fact that they're not polar.
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What is the structure of a phospholipid?
Similar to triglycerides, except that one of the three fatty acids is replaced by a phosphate group. This attaches via a condensation reaction.
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Why do organisms living in very cold climates have more unsaturated fatty acids in their membranes?
This ensures the membrane remains fluid even at very cold temperatures.
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How are triglycerides respired?
Triglyceride split back into glycerol and 3 fatty acids. These are then in cell respiration and broken down further to release carbon dioxide, water and ATP energy.
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How much energy is released in the respiration of lipids?
The respiration of 1g of lipid releases twice as much energy as 1g of carbohydrate, and releases more water.
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How do the properties of lipids make them good energy storage molecules?
Insoluble in water- don't dissolve in cytoplasm. Unreactive- won't affect water potential inside cells or interfere with cell reactions. Stored as complex droplets- lots of energy in small space. Easy to break down.
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What is the structure of cholesterol?
Complex molecule based on a 4 carbon ring structure. Due to its narrow structure, it can sit between the phospholipids in the membrane, making it more stable.
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Why is excess cholesterol a problem?
Can join with bile in the gall bladder to form gall stones. Can be deposited on inner lining of blood vessels, causing atherosclerosis & circulation problems.
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What is Familial Hypercholesterolaemia?
FHC is a genetic disorder of high cholesterol. The body cells produce and secrete cholesterol even when there's enough in the bloodstream. This happens because the cells don't respond to the signals given to stop the cholesterol production.
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What do steroid hormones do?
Travel in the bloodstream until they reach and enter cell where they will have an effect. Because they have a lipid-based structure, they can easily pass across cell membranes.
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What is the main role of triglycerides?
Compact energy store, insoluble in water so doesn't affect water potential of cell.
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What is the main role of phospholipids?
Forms a molecule that is part hydrophobic, and part hydrophilic- ideal for cell surface membranes.
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What is the main role of cholesterol?
Forms a small, thin molecule that gives strength and stability to the phospholipid bilayer.
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Why can't lipids be transported by blood plasma?
They are not water-soluble.
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How are lipids transported?
When lipids are released from adipose tissue, they change back to fatty acids and glycerol. The glycerol can dissolve in the plasma, but the fatty acids have to combines with proteins in the plasma to form lipoproteins.
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Other cards in this set

Card 2


What do lipids include?


Fatty acids, triglycerides and cholesterol.

Card 3


What is a fat?


Preview of the front of card 3

Card 4


What is an oil?


Preview of the front of card 4

Card 5


What are the functions of lipids in living organisms?


Preview of the front of card 5
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