Topic 14: lipids

Question 1

Give the types of lipids

Answer 1

1) Storage lipids
- Triglycerols
2) Membrane lipids
- Phospholipids
- Glycolipids

Question 2

Describe lipids

Answer 2

• Water-insoluble biomolecules
• Highly soluble in organic solvents
• Biological roles = fuel + energy stores + signal molecules + messenger in signal transduction + membranes

Question 3

Give the types of membrane lipids

Answer 3

1) Phospholipids
2) Glycolipids
3) Cholesterol

Question 4

Describe phospholipds

Answer 4

• 2 fatty acids + glycerol + phosphate head
• Polar head
• Hydrophobic tail
• Simplest = phosphatidate
• Small amount present in membrane
• Key intermediate in biosynthesis of other phosphoglycerides

Question 5

Types of phospholipids

Answer 5

• Attachment of alcohol onto phosphate = variety
  1) Phosphatidylcholine
  2) Phosphatidylethanolamine
  3) Phosphatidylserine
  4) Phosphatidylinositol

Question 6

Describe sphingolipids

Answer 6

• Type of phospholipid based on sphingosine instead of glycerol
• E.g. sphingomyelin

Question 7

Describe glycolipids

Answer 7

• Sugar-containing lipid
• Derived from shingosine in animal cells
• Simplest glycolipid = cerebroside = single sugar residue = glu/galactose

Question 8

Describe cholestrol

Answer 8

• Steroid = 4 linked hydrocarbon rings
• In animal membranes NOT in prokaryotes
• 25% membrane lipids in nerve cells

Question 9

Describe triacylglycerols

Answer 9

• Fat storage in form of fatty acid = adipose cells

Question 10

Describe fatty acids

Answer 10

• Carboxylic acids = hydrocarbon chains = 4-36 carbons
• Systematic name = parent hydrocarbon -oic acid

Question 11

Explain the nomenclature for fatty acids

Answer 11

• C1 = C=O
• Start counting from C1
• Number of carbons = X
• Number of double bonds = Y
• X:Y
• Find position of double bond = Z
• X:Y (Δ z)

Question 12

What does ω 3/6 mean?

Answer 12

• ω = last carbon = opposite end to C1
• 3/6 means 3/6 carbons away from ω = double bond

Question 13

Describe ω-3 polyunsaturated fatty acid

Answer 13

• Humans cannot synthesize PUFA a-linolenic acid = in diet
• Can synthesize eicosapentaenoic acid + docosahexaenoic acid
• Imbalance of 3/6 = CVD

Question 14

Describe cis/trans fatty acids

Answer 14

• Naturally occuring = unsaturated fatty acid = double bonds in cis bonds
• Trans fats = food processing
• Trans = bad cholestrol = increased risk of CVD

Question 15

Explain the melting point for fatty acids

Answer 15

• Number of carbons increase = MP increase
• Double bonds = lower melting temp

Question 16

Describe the placement of bonds on fatty acid

Answer 16

• Most common = even number of carbon
• Double bonds = specific locations