Lipids Flashcards

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1
Q

What characteristics do all lipids share?

A
  • contain Carbon, hydrogen & oxygen
  • non-polar molecules - due to large no. C’s and H’s so - insoluble in water
  • soluble in other organic solvents e.g. alcohols
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2
Q

2 main groups of lipids and what are they a component of ?

A

Triglycerides (fats & oils) - component of our diet
Phospholipids - component of cell membranes
- both contain glycerol molecule & fatty acids
- tri: 3 fatty acids chain
- phospho: 2 chains instead of 3rd replaced by phosphate group

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3
Q

How are triglycerides formed?

A
  • via the condensation between 1 molecule of glycerol & 3 molecules of fatty acid - 3 separate condensation reactions
  • each of the chains go through condensation reactions w glycerol so - 3 water molecules produced & 3 ester bonds forming
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4
Q

What are fatty acids?

A
  • long hydrocarbon chain w a carboxylic acid group at one end
  • some contain C double bonds, some don’t
  • AKA R group because: no. of Cs & Hs can vary (R = variable group)
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5
Q

What are the 2 types of fatty acids?

A

Saturated: have only C-C (single bonds between carbons) so form linear hydrocarbon chains

Unsaturated: have 1 or more C=C (double bond between carbons) which causes the hydrocarbon chain to bend

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6
Q

What is the result of having the C-C & C=C?

A
  • saturated fatty acids fit closely together in a regular pattern
  • unsaturated fatty acids push e/o apart forming irregular patterns
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7
Q

Properties of saturated fatty acids?

A
  • contain only C-C bonds - form linear hydrocarbon chains
  • fatty acids can pack closely together
  • strong attractions (intermolecular bonds) between fatty acid chains
  • high mps
  • solids at room temp
  • e.g. fats
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8
Q

Properties of unsaturated fatty acids?

A
  • contain 1 or more C=C - hydrocarbon chains bend
  • these non-linear chains don’t allow fatty acid molecules to pack closely together
  • weaker attractions (intermolecular bonds) between fatty acid chains
  • lower mps
  • liquid at room temp
  • e.g. oils
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9
Q

Properties of triglycerides (due to structure)?

A
  • Energy storage: due to large ratio of energy-storing carbon-hydrogen bonds compared to no. C atoms - lot
  • Metabolic water source: due to high ratio of H atoms compared to O atoms aka can release water if oxidised (essential for animals in desert e.g. camels)
  • Don’t affect water potentials & osmosis -large & hydrophobic so - insoluble in water
  • Relatively low mass so - stored w/o increasing mass & preventing movement
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10
Q

Differences between the condensation & hydrolysis of triglycerides?

A

Condensation:
- produces a triglyceride
- formed from glycerol + 3 fatty acids
- 3 water molecules released
- 3 ester bonds formed

Hydrolysis:
- triglyceride split by addition of 3 water molecules
- 3 ester bonds broken
- glycerol + 3 fatty acids formed

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11
Q

Phospholipids?

A
  • made of: glycerol molecule, 2 fatty acid chains + phosphate group (attached to glycerol)
  • 2 fatty acids also bond to glycerol via 2 condensation reaction - 2 ester bonds
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12
Q

Properties of phospholipids?

A
  • the hydrophilic (can attract + interact w water) head of a phospholipid can attract water - it’s charged
  • due to phosphate being charged - repels other fats
  • fatty acid chain isn’t charged aka hydrophobic tail - repels water but mixes w fats
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13
Q

Result of properties of phospholipids?

A
  • hv 2 charged regions so -polar
  • in water: positioned so heads are exposed to water (as close as poss) & tails are not (as far as poss)…
  • forms a phospholipid bilayer membrane structure - makes up the plasma membrane around cells
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