Biological Molecules - Lipids Flashcards

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1
Q

Describe The Test For Lipids In A Sample

A
  • Dissolve Solid Samples In Ethanol
  • Add An Equal Volume of Water To Ethanol and Shake
  • A Positive Result Will Show A Milky-White Emulsion Formed
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2
Q

How Do Triglycerides Form?

A

A Condensation Reaction Between 1 Glycerol Molecule and 3 Fatty Acids To Form Ester Bonds

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3
Q

Compare Saturated and Unsaturated Fatty Acids

A

Saturated:

  • Only Single Carbon Bonds
  • Straight Chain Molecules With Many Contact Points
  • Higher Melting Point So Is Solid At Room Temperature
  • Found In Animal Fats

Unsaturated:

  • Contain Some Double Carbon Bonds
  • Are Kinked Molecules So Have Fewer Contact Points
  • Lower Melting Point So Is Liquid At Room Temperature
  • Found In Plant Oils
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4
Q

Relate The Structure of Triglycerides to Its Functions

A
  • High Energy:Mass Ratio
  • Insoluble Hydrocarbon Chain = No Effect On Water Potential of Cells and Used For Waterproofing
  • Slow Conductor of Heat So Can Provide Thermal Insulation
  • Less Dense Than Water So Cause For Buoyancy of Aquatic Animals
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5
Q

Describe The Structure and Function of Phospholipids

A

Amphipathic Molecule - Glycerol Molecule (Backbone) Attached to 2 Hydrophobic Fatty Acid Tails & 1 Hydrophilic Phosphate Head

  • Forms Phospholipid Bilayer In Water = Component Of Membranes
  • Tails Can Splay Outwards = Waterproof
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6
Q

Compare Phospholipids & Triglycerides

A
  • Both Have Glycerol Backbone
  • Both May Be Attached To A Variety of Fatty Acids, eg: Saturated, Monounsaturated, Polyunsaturated
  • Both Contain Carbon, Hydrogen & Oxygen
  • Both Formed by Condensation Reactions
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7
Q

Contrast Phospholipids & Triglycerides

A

Phospholipids:

  • 2 Fatty Acids & 1 Phosphate Group Attached
  • Hydrophilic Head and Hydrophobic Tail
  • Used Primarily In Membrane Formation

Triglycerides:

  • 3 Fatty Acids Attached
  • Entire Molecule Is Hydrophobic
  • Used Primarily As A Storage Molecule
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8
Q

Are Phospholipids and Triglycerides Polymers?

A

No; They are not made from repeating units - they are macromolecules

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