lipids Flashcards

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1
Q

contrast saturated and unsaturated fatty acids

A

saturated:
- contain only single carbon bonds
- straight chain molecules and have many contact points
- higher melting point = solid at room temperature
- found in animal fats
unsaturated:
- contain double carbon (C=C) bonds
- ‘kinked’ molecules and have few contact points
- lower melting point = liquid at room temperature
- found in plant oils

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1
Q

how do triglycerides form? draw this

A
  • condensation reaction takes place between 1 molecule of glycerol and 3 fatty acids which forms ester bonds
  • (refer to images)
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2
Q

relate the structure of triglycerides to their functions

A
  • high energy:mass ratio = high calorific value from oxidation so acts as an energy store
  • insoluble hydrocarbon chain = no effect on water potential of cells and is used for waterproofing
  • slow conductor of heat = thermal insulation (e.g. adipose tissue)
  • less dense than water = buoyancy of aquatic animals
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3
Q

describe the structure and function of phospholipids

A
  • amphipathic: glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic polar phosphate head
  • forms phospholipid bilayer in water = component of membranes
  • tails can splay outwards = waterproofing e.g. for skin
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4
Q

are phospholipids and triglycerides polymers? explain your answer

A

no - they are not made from a small repeating unit; instead they are macromolecules

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5
Q

describe the structure and function of cholesterol

A
  • steroid structure of 4 hydrocarbon rings
  • hydrocarbon tail on one side, hydroxyl group (-OH) on the other side
  • adds stability to cell surface phospholipid bilayer by connecting molecules and reducing fluidity
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