Lipids 🦋🦋

• What are Lipids


  A macromolecule containing carbon, hydrogen and oxygen however unlike carbohydrates contain a lower proportion of oxygen.
• Are lipids polar/non polar? Hydrophobic/hydrophillic


  Non polar. Hydrophobic (insoluble in water)
• What are the two groups of a lipid?


  Triglyceride (main components of fats and oils)

  Phospholipids
• What is a triglyceride?


  a lipid made of one glycerol and three fatty acids as the monomers.
• Are triglycerides polar or non-polar? Are they hydrophobic or hydrophilic?


  nonpolar, hydrophobic
• What is glycerol?


  An alcohol (organic molecule that contains a hydroxyl group bonded to a carbon atom.)
• What two groups do fatty acids contain at either end of their hydrocarbon chain (R group)


  A methyl group and a carboxyl group. (RCOOH)
• What two ways can fatty acids vary?


  - the length of their hydrocarbon tail chain (R group)

  - the fatty acid chain (R group) may be saturated or unsaturated. Saturated= single bonds only. Unsaturated= one of more double bond.
• What does it mean if H atoms are on the same side of the double bond? Can they be metabolised by enzymes?


  They are cis-fatty acids, yes.
• What does it mean if H atoms are on the other side of the double bond? Can they be metabolised by enzymes?


  They are trans-fatty acids, no as they cannot form enzyme substrate complexes- linked to CHD.
• How are triglycerides formed?


  condensation of glycerol and 3 fatty acids called esterification where an ester bond forms (when an OH group on glycerol bonds with the COOH group of the fatty acid. An H from the glycerol combines with an OH from the fatty acid to make water. From each ester bond formed a water molecule is realeased. Three fatty acids join to one glycerol to form a triglyceride so for one tryiglyceride to form, three water molecules are released.
• How many water molecules are released in the formation of a triglyceride and why?


  From each ester bond formed a water molecule is realeased. Three fatty acids join to one glycerol to form a triglyceride so for one tryiglyceride to form, three water molecules are released. (Good for dessert animals)
• Triglycerides: in cellular respiration


  The long hydrocarbon chains contain many carbon-hydrogen bonds with little oxygen. So when triglycerides are reduced during cellular respiration, causes these bonds to break releasing energy (used to produce ATP)
• What stores more energy per gram (carb, proteins or triglycerides?)

  Triglycerides.
• Triglycerides are hydrophobic, what does that mean for storage?


  They do NOT cause osmotic water uptake in cells so more can be stored.
• Where do plants store triglyceride


  In their seeds and fruits
• Where do mammals store triglycerides?


  As oil droplets in adipose tissue to help survive when food is scarce.
• Triglyceride: Insulation


  Part of the composition of the myelin sheath that surrounds nerve fibres, provides insulation which increase speed of nerve impulses. Compose layer of adipose tissue layer below skin which acts as insulation against heat loss.
• Triglyceride: Buoyancy


  Low density of fat tissue increases ability of animals to float more easily.
• Triglyceride: protection


  Adipose tissue in mammals helps protect organs from risk of damage.
• Phospholipids structure


  A type of lipid formed from the monomer glycerol and fatty acids. Only two fatty acids bonded to a glycerol molecule as one has been replaced by a phosphate ion.
• Is a phospholipid soluble in water (hydrophilic?)


  As the phosphate in polar it is hydrophilic. (Head)

  As the fatty acid (tails) are non-polar they are hydrophobic.

  They are amphipathic (have both hydrophobic and hydrophilic parts) means they form a monolayer and a bilayer in water.
• What is the role of a phospholipid?


  They are the main component of cell membranes. The hydrophobic fatty acid tails face inward away from the water, creating a barrier that separates the inside of the cell from the outside to water soluble molecules. Their hydrophilic phosphate head faces outwards towards the water inside and outside the cell and forms hydrogen bonds with water molecules creating a strong separation of inside and outside of cell.

  
  

  OVERALL- helps control what enters and exits the cell while maintains an internal environment.
• Will the cell be more or less fluid with mainly saturated fatty acid tails.


  Less fluid.
• Emulsion test for lipids


  - Shake test substance with ethanol for about a minute, then pour the solution into water.

  
  

  - Any lipid will show up as a milky emulsion.

  
  

  - The more lipid there is, the more noticeable the milky colour will be.

  - is qualitative
• What is a saturated fatty acid?


  Saturated= single bonds only between the carbon atoms in the hydrocarbon tail. Fatty acid is 'saturated' with carbon meaning each carbon in hydrocarbon tail (except for final carbon) is bonded to two hydrogen atoms.
• What is an unsaturated fatty acid?


  Unsaturated= at least one carbon-carbon double bond. Cause hydrocarbon tail to kink (bend slightly) meaning they are not as straight as saturated fatty acids. The fatty acid is unsaturated as it does not contain the maximum number of hydrogen atoms possible (as each carbon in double bond can only bond to one hydrogen instead of two.)