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| Question | Answer |
| What are the properties of lipids? | Non-polar compounds (insoluble) Made up of C, H and O (though less oxygen than carbohydrates) |
| What is the structure of fatty acids? | Organic acids with a carboxyl (-COOH) group at one end and a long hydrocarbon tail (the R group) joined to the carboxyl group General formula = RCOOH |
| What is the difference between saturated and unsaturated compounds? | Saturated compounds only have C-C bonds Unsaturated compounds have at least one C=C bond |
| What is the structure of triglyceride? |
3 ester bonds
Glycerol + 3 hydrocarbon tails
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| How are triglycerides formed? |
Each ester bond is formed by a condensation reaction
The process in which triglycerides are synthesised is called esterification
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| How are triglycerides broken down? | Each ester bond is broken in a hydrolysis reaction |
| Complete the sentences: When _________, triglycerides release more energy for use in _____________ than carbohydrate. They also produce a lot of _____________ ________when oxidised (important for desert animals, e.g. camel's hump = fat). They are stored under the _____ where they act as a heat ____________. | When OXIDISED, triglycerides release more energy for use in RESPIRATION than carbohydrate. They also produce a lot of METABOLIC WATER when oxidised (important for desert animals, e.g. camel's hump = fat). They are stored under the SKIN where they act as a heat INSULATOR. |
| What is the structure of a phospholipid? |
Made up of one glycerol, one phosphate and two fatty acids
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| Complete the sentence: The phosphate group is ___________ and the fatty acid tails are _____________. | The phosphate group is HYDROPHILIC and the fatty acid tails are HYDROPHOBIC. |
| Describe the two common arrangements of phospholipids |
As a micelle and as a monolayer
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| What is the structure of cholesterol? |
Another type of lipid
Hydrocarbon ring structure attached to a hydrocarbon tail
The ring structure has a polar -OH group attached to it
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| What are the functions of triglycerides? | In animals and plants = energy storage molecules Some bacteria use them to store both energy and carbon Good for storage - long hydrocarbon tails of the fatty acids contain lots of chemical energy (lipids contain twice as much energy per gram as carbohydrates because of these tails) Insoluble Bundles together as insoluble droplets in cells as the fatty acid tails are hydrophobic (micelles) |
| What are the functions of phospholipids? | Found in cell membranes of all eukaryotes and prokaryotes Makes up the phospholipid bilayer Cell membranes control what enters and leaves a cell The center of the bilayer is hydrophobic so water-soluble substances cannot easily pass through it |
| What are the functions of cholesterol? |
In eukaryotic cells, cholesterol molecules help strengthen the cell membrane by interacting with the phospholipid bilayer
Has a small and flattened shape (allowing cholesterol to fit in between the phospholipid molecules in the membrane)
Bind to the hydrophobic tails of the phospholipids, causing them to pack more closely together (helps make membrane less fluid and more rigid)
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