Lipids Flashcards

Describe structure and properties of amino acids Describe formation and breakage of peptide bond Explain primary, secondary, tertiary and quaternary structure Explain effects of temperature and pH Describe structure and properties of haemoglobin and collagen

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1
Q

Glycerol

A

3 carbon alcohol, each bearing hydroxyl group (OH)

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2
Q

Fatty acid

A

Long non-polar, hydrophobic hydrocarbon chains
Carboxyl group (COOH) at one end
Saturated or unsaturated
Cannot form hydrogen bonds with water

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3
Q

Triglyceride molecule

A

3 fatty acid molecules + 1 glycerol molecule
Ester linkage (between OH and COOH group)
Condensation reaction

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4
Q

Properties of triglycerides

A

Non-polar -> do not form H-bonds with water molecules
Hydrophobic
Insoluble -> does not affect water potential of cells

Cis-double bond (unsaturated fatty acid chains) -> kinks -> pack less closely

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5
Q

Functions of triglycerides

A

Compact energy storage
Higher proportion of carbon and hydrogen atoms and lower proportion of oxygen -> higher proportion of C-H bonds -> more reduced -> release more energy during oxidation

Produces metabolic water

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6
Q

Other functions of triglycerides

A

Protect internal organs
Thermal insulation
Improve buoyancy
Storage of fat soluble vitamins like A, D and K

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7
Q

Phospholipids

A

2 fatty acid molecules + 1 glycerol molecule + 1 phosphate group (negative electrical charge)
Phosphoester linkage

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8
Q

Properties of phospholipids

A

Amphipathic -> both hydrophilic (negatively-charged phosphate head) and hydrophobic (non-polar hydrophobic hydrocarbon tails) regions

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9
Q

Functions of phospholipids

A

Membranes -> phospholipid bilayer -> boundary
Hydrophobic core only permeable to small hydrophobic solutes and low permeability to polar and charged molecules/ions -> barrier -> partially permeable
Can move laterally -> fluid

Form vesicles

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10
Q

Properties of steroids

A

Slightly amphipathic -> hydrophobic hydroxyl group and hydrophobic ring structure

OH group aligns with phosphate heads of phospholipids (H-bonds)
Remaining portion tucked into hydrophobic core (Van der Waals forces)

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11
Q

Functions of steroids

A

Cholesterol regulates membrane fluidity -> stabilises membrane

At high temperatures -> restrict phospholipid movement through its interactions -> prevented from being overly fluid

At low temperatures -> prevents close packing of phospholipids -> prevents solidification/from being overly firm

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12
Q

Fat test

A
Ethanol emulsion test
2cm3 of ethanol
2 drops of test sample
Mix well and allow it to stand for 2 min
Decant ethanol into another test tube containing 2cm3 water
White emulsion if lipids present
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