Lipids

Question 1

Lipids

Answer 1

Diverse and ubiquitous group of organic compounds that are insoluble in water but soluble in organic solvents

Question 2

Backbone classification

Answer 2

1. Glycerol based
2. Non-glycerol based
3. Eicosanoids

Question 3

Glycerol-based

Answer 3

• simple
• fats (animal) and oils (plants)
• triglycerides (TAGs)= 3 fatty acids + glycerol
• Fxn: (1) energy storage (2) major macronutrient
• complex
  1. Phospholipids = 2 F.A. + polar group + glycerol
  
  • Fxn: (1) structural component (2) precursor for secondary messengers (PIP3, PIP4, and DAG)
    2. Glycolipids = 2 F.A. + sugar + glycerol

Question 4

Non-glycerol based

Answer 4

1. Sphingolipids

2. Steroids

Question 5

Sphingolipids

Answer 5

• sphingosine backbone
  1. Phosphosphingolipids
• sphingomyelin
• phosphoethanolamine
  2. Glycosphingolipids
• gangliosides, cerebrosides, globosides, sulfatides
• Specific Fxn: (1) reg. Cell interactions (2) growth and dev. (3) antigenic properties - receptors for toxins, viruses, and microbes

Fxn:

1. Structural: cell mem and lipoproteins
2. Signaling: precursors for secondary messengers

Question 6

Steroids

Answer 6

*ABCD ring structure
*sterols- subgroup w/ -OH at C3 of A ring
1. Cholesterol
A) free: -OH group on C3 of A ring
*animal cell membrane - important for fluidity
2. Cholesterol ester: ester at C3 of A ring
*storage and transport form
*Fxns:
1. Structural: animal cell mem (fluidity, integrity, signaling), lipoproteins (plasma lipid transport)
2. Precursor for: bile acids and salts, steroid hormones, and vitamin D

Question 7

Eicosanoids

Answer 7

• derived from arachidonic acid
  1. Prostaglandins: most tissues, vasoconstriction/dilation, smooth muscle contraction/relaxation, induce labor, required for fever response
  2. Prostacyclins: vessel endothelium, vasodilation
  3. Thromboxanes: in platelets, vasoconstriction
  4. Leukotriens: immune cells, mediate immune response