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Questions and Answers
Which statement correctly defines simple lipids?
Which statement correctly defines simple lipids?
Which of the following is a type of complex lipid?
Which of the following is a type of complex lipid?
What distinguishes sphingophospholipids from glycerophospholipids?
What distinguishes sphingophospholipids from glycerophospholipids?
Which of the following substances can be classified as derived lipids?
Which of the following substances can be classified as derived lipids?
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What distinguishes saturated fatty acids from unsaturated fatty acids?
What distinguishes saturated fatty acids from unsaturated fatty acids?
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Phospholipids primarily participate in which function?
Phospholipids primarily participate in which function?
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What type of alcohol is found in the structure of neutral fats?
What type of alcohol is found in the structure of neutral fats?
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Which of the following is considered an essential fatty acid?
Which of the following is considered an essential fatty acid?
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In terms of molecular weight, what characterizes the alcohols used in waxes?
In terms of molecular weight, what characterizes the alcohols used in waxes?
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What is the carbon chain length of medium-chain fatty acids?
What is the carbon chain length of medium-chain fatty acids?
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Which fatty acid is an example of a polyunsaturated fatty acid?
Which fatty acid is an example of a polyunsaturated fatty acid?
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What additional component is often present in phospholipids apart from fatty acids and alcohol?
What additional component is often present in phospholipids apart from fatty acids and alcohol?
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How are phospholipids further classified?
How are phospholipids further classified?
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What is the primary role of essential fatty acids in the body?
What is the primary role of essential fatty acids in the body?
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Which of the following is NOT considered a function of phospholipids?
Which of the following is NOT considered a function of phospholipids?
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What does the acid number in fats and oils indicate?
What does the acid number in fats and oils indicate?
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Which of the following fatty acids is an omega-6 fatty acid?
Which of the following fatty acids is an omega-6 fatty acid?
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What type of fatty acids are prostaglandins derived from?
What type of fatty acids are prostaglandins derived from?
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What characteristic is common among long-chain fatty acids?
What characteristic is common among long-chain fatty acids?
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What role do phospholipids play in preventing fatty liver?
What role do phospholipids play in preventing fatty liver?
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Which statement about arachidonic acid is accurate?
Which statement about arachidonic acid is accurate?
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What function do phospholipids serve in reverse cholesterol transport?
What function do phospholipids serve in reverse cholesterol transport?
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Which lipid type does not contain a phosphate group?
Which lipid type does not contain a phosphate group?
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What is a primary function of lipoproteins like HDL?
What is a primary function of lipoproteins like HDL?
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What is a characteristic of derived lipids?
What is a characteristic of derived lipids?
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Which of the following is NOT a function of lipids?
Which of the following is NOT a function of lipids?
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Which is the primary role of cephalins in the body?
Which is the primary role of cephalins in the body?
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Which statement accurately describes the properties of fats?
Which statement accurately describes the properties of fats?
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Which component is a key feature of glycolipids?
Which component is a key feature of glycolipids?
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What does a higher saponification number indicate about a fat or oil?
What does a higher saponification number indicate about a fat or oil?
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Which condition would lead to an increased acid number in oils?
Which condition would lead to an increased acid number in oils?
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What is the significance of a low iodine number in fats or oils?
What is the significance of a low iodine number in fats or oils?
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What are the final products of saponification?
What are the final products of saponification?
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What does the saponification number of human fat typically range from?
What does the saponification number of human fat typically range from?
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What does acid hydrolysis achieve in relation to fats?
What does acid hydrolysis achieve in relation to fats?
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Which of the following correctly describes the structure of soaps?
Which of the following correctly describes the structure of soaps?
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What does the iodine number help to determine in oils?
What does the iodine number help to determine in oils?
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Which of the following statements about refined oils is true?
Which of the following statements about refined oils is true?
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What reaction occurs when fatty acids are reacted with alcohols?
What reaction occurs when fatty acids are reacted with alcohols?
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Study Notes
Lipid Chemistry
- Lipids are organic compounds insoluble in water but soluble in organic solvents like chloroform, ether and benzene
- Classification of lipids is based on their chemical structures.
- Simple lipids are esters of fatty acids (FAs) with various alcohols.
- Neutral fats or oils are esters of FAs with the alcohol glycerol.
- Waxes are esters of FAs with higher molecular weight monohydric alcohols.
Complex Lipids
- Complex lipids are esters of FAs with alcohols containing additional prosthetic groups.
- Phospholipids contain FAs + an alcohol + phosphoric acid, often with nitrogen-containing bases.
- Glycerophospholipids have glycerol as the alcohol.
- Examples: Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, plasmalogens, cardiolipins
- Sphingophospholipids have sphingosine as the alcohol.
- Example: Spingomyelins
- Glycerophospholipids have glycerol as the alcohol.
- Glycolipids have FAs + the alcohol sphingosine + a carbohydrate with a nitrogen base.
- They do not contain a phosphate group.
- Examples: Cerebrosides, gangliosides
- Lipoproteins contain lipid with the prosthetic group protein.
- Examples: Chylomicrons, very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoprotein (HDL)
Derived Lipids
- Derived lipids are derivatives obtained from the hydrolysis of simple or complex lipids, with lipid characteristics.
- Examples: Fatty acids, steroids, cholesterol, vitamin A and D
Functions of Lipids
- Structural component of cell membranes.
- Storage form of energy.
- Precursor of many steroid hormones, vitamin D.
- Act as a thermal insulator.
- Protection of internal organs.
- Help in absorption of fat-soluble vitamins.
- Lipoproteins transport lipids.
- Fatty acids act as surfactants.
- Fatty acids improve taste and palatability.
- Fatty acids act as electric insulators in neurons.
Fatty Acids
- Fatty acids are naturally occurring carboxylic acids with an unbranched carbon chain and an even number of carbon atoms.
- Saturated fatty acids contain only carbon-carbon single bonds.
- Example: Palmitic acid
- Unsaturated fatty acids contain one or more double bonds.
- Example: Oleic acid
Essential Fatty Acids
- Essential fatty acids cannot be synthesized by the body and must be obtained from the diet.
- -linolenic acid (ALA): an omega-3 fatty acid.
- Linoleic acid (LA): an omega-6 fatty acid.
Functions of Essential Fatty Acids
- Membrane structure and function.
- Cholesterol transport.
- Lipoprotein formation.
- Prevention of fatty liver.
- Precursor for synthesis of eicosanoids.
Testing Purity of Fats and Oils
- Acid number: Measures free fatty acids in oil or fat.
- Higher acid number indicates spoilage or contamination.
- Saponification number: Measures the average molecular size of fatty acids present in oil or fat.
- Higher number indicates shorter chain fatty acids.
- Iodine number: Measures the degree of unsaturation in oil or fat.
- Lower iodine number indicates less unsaturation.
Chemical Reactions of Fatty Acids
Esterification
- Fatty acids react with alcohols to form esters and water.
Acid Hydrolysis
- Reverses esterification.
- Fatty acids are produced from esters.
Saponification
- Base-catalyzed hydrolysis of an ester.
- Products are alcohol and a soap (ionized salt).
- Soap forms micelles which dissolve oil and dirt particles.
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Description
Explore the fascinating world of lipid chemistry, including the classification of simple and complex lipids. Understand the structures and examples of various types of lipids, including phospholipids and glycolipids, and their significance in biological systems.
