Chapter 26. Lipids
Recommended Article: 【Organic Chemistry】 Organic Chemistry Table of Contents
1. Fatty Acids
2. Steroids
a. Composition of Living Organisms
1. Fatty Acids
⑴ Characteristics
① Serum albumin aids in the movement of fatty acids in the blood plasma.
② Unsaturated fatty acids: Used in the synthesis of new substances, incapable of beta oxidation.
⑵ Type 1. Saturated Fatty Acids
① 1-1. Lauric Acid (12:0)
○ 12 carbons, 0 double bonds
② 1-2. Myristic Acid (14: 0)
○ 14 carbons, 0 double bonds
③ 1-3. Palmitic Acid (16:0)
○ 16 carbons, 0 double bonds
④ 1-4. Stearic Acid (18:0)
○ 18 carbons, 0 double bonds
⑶ Type 2. Unsaturated Fatty Acids
① 2-1. Palmitoleic Acid (16:1)
○ 16 carbons, 1 double bond
○ ω-7: Alkene formation starting from the 7th carbon from the methyl end
② 2-2. Oleic Acid (18:1)
○ 18 carbons, 1 double bond
○ ω-9: Alkene formation starting from the 9th carbon from the methyl end
③ 2-3. Linoleic Acid (18:2)
○ 18 carbons, 2 double bonds
○ ω-6: Alkene formation starting from the 6th carbon from the methyl end
④ 2-4. α-Linolenic Acid (18:3)
○ 18 carbons, 3 double bonds
○ ω-3: Alkene formation starting from the 3rd carbon from the methyl end
○ Found in vegetables and plant oils (corn oil)
○ Prevents skin diseases and possesses growth factors
⑤ 2-5. Arachidonic Acid (20:4)
○ 20 carbons, 4 double bonds
○ ω-6: Alkene formation starting from the 6th carbon from the methyl end
○ Present in animal fats and prevents skin diseases
⑥ Omega-3 Fatty Acids
○ Unsaturated fatty acids that form the first alkene from the 3rd carbon from the methyl end
○ Promotion of red blood cell aggregation and prostaglandin production to prevent heart disease: It is also said to be capable of preventing cancer.
○ EPA and DHA: Omega-3 fatty acids abundant in fish.
○ DHA: Beneficial for young children’s brain development
⑦ Linoleic Acid → Arachidonic Acid
⑧ Arachidonic Acid → PG, Thromboxane
○ Mediating enzyme: C.O.X
○ PG: Increases blood clotting, causes headaches, uterine contractions, raises the set point, promotes gastric mucosal formation
○ Thromboxane: Blood clotting
○ Arachidonic Acid → Leukotrienes
○ PG, Thromboxane, Leukotrienes: Self-degrade.
2. Steroids
⑴ Cholesterol: 3 hexagonal rings + 1 pentagonal ring + -OH
① Distributed regularly in and out of membranes
② Stabilizes membranes
③ Precursor
○ Adrenal cortex hormones, Vitamin D
○ Vitamin D: Activates calcium pumps in the intestine, increasing calcium absorption
④ Cholesterol is absent in the cell membrane of E. coli
3. Phospholipids
⑴ Four major components of animal cell membranes, accounting for over 50%, Phosphatidylcholine, Phosphatidylethanolamine, Phosphatidylserine, Sphingomyelin
⑵ Asymmetry of Phospholipids involves flippase and floppase
① Charge imbalance: Outside of the cell membrane is positively charged, inside is negatively charged
② Ligand imbalance: Phosphatidylcholine, Phosphatidylinositol, Phosphatidylserine, etc.
⑶ Type 1. Glycerophospholipids: Glycerol skeleton + Phospholipid × 2 + Phosphate × 1 + Substituent × 1
① Phosphatidylcholine: Extracellular phospholipid, positively charged.
② Phosphatidylethanolamine: Intracellular phospholipid
③ Phosphatidylinositol: Intracellular phospholipid, negatively charged.
④ Phosphatidylserine: Intracellular phospholipid, neutral. Cell apoptosis occurs when asymmetry is destroyed.
⑷ Type 2. Sphingolipids: Sphingosine skeleton + Sphingosine tail × 1 + Phospholipid × 1 + Phosphate × 1 + Substituent × 1, Extracellular Phospholipid.
① Synthesis
○ Step 1. Amino group of sphingosine is acylated
○ Step 2. Ceramide
○ Step 3. Sphingomyelin, cerebroside, ganglioside
② Role 1. The low-fluidity phospholipid used to anchor receptor and carrier-dense areas (lipid rafts).
○ Lipid raft: High cholesterol, High sphingolipids, High saturated fatty acids, High fatty acid chain length, Having caveolin.
○ Major recognition glycoproteins are also distributed in lipid rafts
③ Role 2. Formation of neuron myelins
④ Role 3. ABO blood type antigens
⑸ Type 3. Micelle
⑹ Type 4. Liposomes: Applied in drug delivery
① General size: Diameter of 90 nm
⑺ Type 5. Platelet Activating Factor (PAF): Ether-linked
⑻ Glycolipids are also located in extracellular phospholipids for cell-cell recognition.
4. Lipid Metabolism
Input: 2019.01.14 18:57