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Questions and Answers
What is the primary structural feature of lipids?
What role do apolipoproteins play in lipoproteins?
Which lipoprotein is known as 'bad cholesterol'?
What process involves the hydrolysis of triglycerides?
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What is a consequence of oxidative rancidity in triglycerides?
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Which statement about chylomicrons is true?
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What results from the hydrogenation of unsaturated fatty acids?
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Which lipoprotein is primarily responsible for removing cholesterol from the bloodstream?
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Study Notes
Lipids
- Lipids are composed of a glycerol backbone with two fatty acid tails and a phosphate group.
- They are arranged in a bilayer manner, with hydrophilic heads facing outwards and hydrophobic tails inwards.
Lipoproteins
- Lipoproteins are made of protein and fat, and carry cholesterol throughout the bloodstream.
- Their structure includes triglycerides, cholesterol, and phospholipids.
- Apolipoproteins function as carrier proteins and serve as cofactors for enzymes that metabolize lipoproteins.
Examples of Lipoproteins
- Chylomicrons: Large, triglyceride-rich lipoproteins produced in enterocytes from dietary lipids (fatty acids and cholesterol). They have the highest triglyceride content.
- VLDL: Very-low-density lipoproteins are made in the liver, have a high lipid concentration, and eventually become LDL.
- IDL: Intermediate-density lipoproteins form from the degradation of VLDL and HDL, and enable fat and cholesterol to move within the bloodstream, potentially promoting atheroma.
- LDL: Low-density lipoproteins are considered "bad cholesterol" as they are the main transporter of cholesterol.
- HDL: High-density lipoproteins are considered "good cholesterol" as they absorb cholesterol and carry it to the liver to be flushed from the body.
Chemical Properties of Lipids
- Hydrolysis of Triglycerides: Reaction with water to form carboxylic acid and alcohol.
- Saponification: Triacylglycerols are hydrolyzed (through alkaline hydrolysis) to produce soap.
- Hydrogenation: C-C double bonds in unsaturated fatty acids are hydrogenated to produce saturated fatty acids.
- Halogenation: Unsaturated fatty acids in fats and oils react with halogens through addition at the double bonds, leading to decolorization of the halogen solution.
- Rancidity: Fats develop a disagreeable odour due to hydrolysis and oxidation reactions. Oxidative rancidity occurs in triacylglycerols containing unsaturated fatty acids.
Lipid Profile Values
- Normal total cholesterol: 240 mg/dL
- HDL-C (good cholesterol) is increased when fasting for up to 12 hours before testing.
- HDL-C is associated with heart disease:
- For men, higher values indicate a lower risk.
- For women, higher values indicate a lower risk.
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Description
Dive into the essential components of lipids and lipoproteins, exploring their structures and functions. Learn how lipoproteins like chylomicrons, VLDL, and IDL contribute to lipid transport in the body. This quiz will enhance your understanding of these vital molecules and their role in health.
