Questions and Answers
What is the main characteristic of lipids that makes them insoluble in water?
What is the function of lipids in the absorption of vitamins?
What is the term for fatty acids that cannot be synthesized in the body?
What is the term for the bond that forms between fatty acids and alcohols?
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What is the classification of lipids that includes fats and waxes?
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What is the term for fatty acids with less than 10 carbon atoms?
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What is the system of numbering carbon atoms in fatty acids starting from the carboxyl group?
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What is the biomedical importance of lipids as structural components of membranes?
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What does the delta (Δ) numbering system indicate in fatty acid notation?
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Which of the following is a characteristic of saturated fatty acids?
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What is a characteristic of essential fatty acids?
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What is the function of the enzyme system in the human body regarding fatty acids?
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What is the difference between monounsaturated and polyunsaturated fatty acids?
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What is the use of nitroglycerol?
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What does the omega (ω) system indicate in fatty acid notation?
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What is the characteristic of simple lipids?
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What is an example of a polyunsaturated fatty acid?
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What is the systemic name of palmitic acid?
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What is true about waxes?
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What are nonessential fatty acids?
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What is the source of energy provided by each gram of body fat?
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What is the characteristic of ω3 polyunsaturated fatty acids?
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What is an example of a dietary source of triacylglycerols?
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What is a characteristic of simple triacylglycerols?
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Which of the following lipoproteins is responsible for transporting exogenous lipid from the intestine to all cells?
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Which of the following lipoprotein classes contains mainly cholesterol and is involved in the transport of cholesterol from cells back to the liver?
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Which of the following lipoproteins is formed from VLDLs and carries cholesterol to cells?
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What is the primary reason for the milky appearance of plasma after a fatty meal?
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Which of the following is NOT a characteristic of derived lipids?
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What is the main difference between phospholipids and glycolipids?
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Which of the following statements about lipoproteins is TRUE?
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Which of the following is NOT a type of lipoprotein?
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What enzyme is stimulated by heparin to manage chylomicrons in the bloodstream?
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Which of the following describes the fate of glycerol after its conversion in the metabolic pathway?
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What is one of the fates of fatty acids during oxidation for energy production?
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Which tissue is not capable of undergoing β-oxidation of fatty acids?
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What product is formed from the oxidation of odd-numbered fatty acids?
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Which of the following is a synthesis product of fatty acid metabolism?
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Study Notes
Lipid Chemistry
- Lipids are organic compounds formed from alcohol and fatty acids combined together by ester bonds.
- Lipids are insoluble in water but soluble in organic solvents such as ether, benzene, acetone, and chloroform.
- The hydrophobic nature of lipids is due to the predominance of hydrocarbon chains (-CH2-CH2-CH2-) in their structure.
Biomedical Importance of Lipids
- Lipids are a source of energy with a high energy value.
- They are structural components of membranes (phospholipids and cholesterol).
- Lipids are metabolic regulators (e.g., steroid hormones).
- They help in the absorption of fat-soluble vitamins (A, D, E, and K).
- Lipids provide a cushioning effect to protect internal organs.
- They provide insulation against changes in external temperature (subcutaneous fat).
- Lipids act as electric insulators in neurons.
Classification of Lipids
- Simple lipids are esters of fatty acids with various alcohols.
- Fatty acids are water-insoluble "long chain hydrocarbons".
- Fatty acids may be saturated or unsaturated.
- They are classified as essential or nonessential based on whether they can be synthesized in the body.
Fatty Acids
- Fatty acids have a general formula of CH3-(CH2)n-COOH where n is the number of methylene groups.
- They can be saturated (no double bonds) or unsaturated (one or more double bonds).
- The naming of fatty acids is based on the number of carbons and the position of double bonds.
- Omega-3, omega-6, and omega-9 fatty acids are classified based on the position of the first double bond.
Alcohols
- Alcohols associated with lipids include glycerol, cholesterol, and higher alcohols.
- Glycerol is an alcohol containing three (-OH) groups.
- It can combine with one fatty acid to form monoacylglycerol.
Simple Lipids
- Simple lipids are formed only from alcohols and fatty acids.
- There are two classes of simple lipids: acylglycerols and waxes.
- Acylglycerols are esters of one, two, or three fatty acids with glycerol.
- Waxes are combinations of fatty acids and long-chain alcohols.
Triacylglycerols (Triglycerides)
- Triacylglycerols are called neutral fats because they carry no charge.
- They are stored mainly in the cytoplasm of adipose tissue cells.
- Each gram of fat gives 9.3 calories.
- Dietary sources of triacylglycerols include animal and plant sources.
Compound Lipids
- Compound lipids contain, in addition to esters of fatty acids with alcohols, other groups.
- They are classified into phospholipids, glycolipids, sulfolipids, and lipoproteins.
Lipoproteins
- Lipoproteins are complexes of lipids with proteins that transport lipids in body fluids.
- They can be classified into five main groups: chylomicrons, VLDL, IDL, LDL, and HDL.
- Each type has a specific function in lipid transport and metabolism.
Derived Lipids
- Derived lipids are formed when simple and compound lipids undergo hydrolysis.
- Examples of derived lipids include cholesterol, carotenes, steroids, prostaglandins, ketone bodies, and fat-soluble vitamins.
Lipid Metabolism
- Lipid metabolism involves the breakdown and synthesis of lipids in the body.
- Lipoprotein lipase enzyme acts on triacylglycerols of chylomicrons, converting them into glycerol and free fatty acids.
- Glycerol and fatty acids are taken up by different tissues for energy production, storage, or synthesis of other compounds.
Fatty Acid Oxidation
- Fatty acid oxidation occurs in three different pathways: α, β, and ω.
- β-Oxidation occurs in the mitochondria of liver, kidney, heart, and skeletal muscles.
- The brain and red blood cells do not have mitochondria, so β-oxidation does not occur in these tissues.
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Description
Learn about the definition and properties of lipids, including their solubility and hydrophobic nature. This quiz covers the basics of lipid chemistry.