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Questions and Answers
Which type of lipid primarily makes up the majority of nutritional lipids?
Which type of lipid primarily makes up the majority of nutritional lipids?
What characteristic distinguishes saturated fatty acids from unsaturated fatty acids?
What characteristic distinguishes saturated fatty acids from unsaturated fatty acids?
Why do saturated fatty acids typically have high melting points?
Why do saturated fatty acids typically have high melting points?
What type of fatty acid contains only one double bond?
What type of fatty acid contains only one double bond?
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Which of the following statements about lipids is incorrect?
Which of the following statements about lipids is incorrect?
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What is produced in small amounts in the stomachs of ruminating animals?
What is produced in small amounts in the stomachs of ruminating animals?
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Which of the following statements about cholesterol is true?
Which of the following statements about cholesterol is true?
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How is cholesterol transported in the bloodstream?
How is cholesterol transported in the bloodstream?
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Which of the following options contributes to higher cholesterol levels?
Which of the following options contributes to higher cholesterol levels?
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What is a characteristic of trans fats compared to cis fats?
What is a characteristic of trans fats compared to cis fats?
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What type of fats are solid at room temperature?
What type of fats are solid at room temperature?
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Which of the following fatty acids is considered essential for humans?
Which of the following fatty acids is considered essential for humans?
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What process is used to convert unsaturated fats into saturated fats?
What process is used to convert unsaturated fats into saturated fats?
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What is the result of saponification of a triglyceride?
What is the result of saponification of a triglyceride?
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Which fatty acid is primarily found in fish oils and has a polyunsaturated structure?
Which fatty acid is primarily found in fish oils and has a polyunsaturated structure?
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Cis and trans fatty acids differ in what way?
Cis and trans fatty acids differ in what way?
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What term is used to describe fatty acids that cannot be synthesized by the human body?
What term is used to describe fatty acids that cannot be synthesized by the human body?
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Which of the following oils is typically liquid at room temperature?
Which of the following oils is typically liquid at room temperature?
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What is the characteristic behavior of whale oil at different depths while swimming?
What is the characteristic behavior of whale oil at different depths while swimming?
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Which statement about soaps and detergents is correct?
Which statement about soaps and detergents is correct?
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Why is water at 4°C considered the most dense?
Why is water at 4°C considered the most dense?
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What causes curd formation in soaps when used in hard water?
What causes curd formation in soaps when used in hard water?
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What property of ice makes it unique compared to most substances?
What property of ice makes it unique compared to most substances?
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What structural feature distinguishes unsaturated fatty acids from saturated fatty acids?
What structural feature distinguishes unsaturated fatty acids from saturated fatty acids?
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Which of the following fatty acids has the highest melting point?
Which of the following fatty acids has the highest melting point?
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What characterizes triacylglycerols?
What characterizes triacylglycerols?
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Why do unsaturated fatty acids generally have lower melting points than saturated fatty acids?
Why do unsaturated fatty acids generally have lower melting points than saturated fatty acids?
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How are fats typically characterized in terms of their physical state at room temperature?
How are fats typically characterized in terms of their physical state at room temperature?
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What is a consequence of increasing unsaturation in fatty acids?
What is a consequence of increasing unsaturation in fatty acids?
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Which fatty acid is classified as polyunsaturated and has a melting point of -11 °C?
Which fatty acid is classified as polyunsaturated and has a melting point of -11 °C?
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What type of reaction is described by the hydrolysis of fatty acids?
What type of reaction is described by the hydrolysis of fatty acids?
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What is the primary function of High Density Lipoproteins (HDLs)?
What is the primary function of High Density Lipoproteins (HDLs)?
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Which statement differentiates Low Density Lipoproteins (LDLs) from High Density Lipoproteins (HDLs)?
Which statement differentiates Low Density Lipoproteins (LDLs) from High Density Lipoproteins (HDLs)?
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Which food item has the highest cholesterol content?
Which food item has the highest cholesterol content?
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What type of fatty acids are more prevalent in LDLs compared to HDLs?
What type of fatty acids are more prevalent in LDLs compared to HDLs?
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What role does 7-dehydrocholesterol play in the body?
What role does 7-dehydrocholesterol play in the body?
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How is lecithin classified in terms of its chemical composition?
How is lecithin classified in terms of its chemical composition?
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What characteristic do all phospholipids share with regard to their structure?
What characteristic do all phospholipids share with regard to their structure?
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Which of the following statements is true about the role of lecithin in food products?
Which of the following statements is true about the role of lecithin in food products?
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Which nutrient is needed for the biosynthesis of phospholipids?
Which nutrient is needed for the biosynthesis of phospholipids?
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What property allows phospholipids to form a bilayer in cell membranes?
What property allows phospholipids to form a bilayer in cell membranes?
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Study Notes
Lipids
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Lipids are organic substances found in living systems.
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They are insoluble in water but soluble in organic solvents.
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Lipids have mostly carbon and hydrogen atoms. Some also have a few polar atoms/functional groups.
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Lipids include fats, oils, steroids, and waxes.
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Fats and oils make up 95% of nutritional lipids; the remaining 5% are steroids and other functional lipids.
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Fats are solid triglycerides.
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Oils are liquid triglycerides.
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Lipids are classified as simple, complex, and derived lipids.
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Simple lipids include fats and oils (triglycerides), waxes, steroids, and fat-soluble vitamins.
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Complex lipids include phospholipids and glycolipids.
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Derived lipids include steroids, fat-soluble vitamins, and others.
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Simple lipids are esters of fatty acids (FAs) with various alcohols.
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Neutral fats/oils: The alcohol is glycerol.
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Waxes: The alcohol is any alcohol other than glycerol.
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Complex lipids are products of hydrolysis that have FAs and an alcohol with additional prosthetic groups.
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Examples of complex lipids: Phospholipids, Glycolipids, Lipoproteins
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Lipids have several important functions:
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Storage form of energy
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Structural component of cell membranes
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Precursor of many steroid hormones
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Protection of internal organs
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Vitamin D precursor
Fatty Acids
- Fatty acids are long-chain carboxylic acids.
- They typically have 12-18 carbon atoms.
- They are insoluble in water.
- They are either saturated or unsaturated.
- Saturated fatty acids have only single bonds between carbon atoms.
- Monounsaturated fatty acids have one double bond between carbon atoms.
- Polyunsaturated fatty acids have two or more double bonds between carbon atoms.
Saturated Fatty Acids
- Molecules fit closely together in a regular pattern
- Strong attractions (dispersion forces) between fatty acid chains
- High melting points, making them solids at room temperature.
- Some examples are capric acid (10 C atoms), lauric acid (12 C atoms), myristic acid (14 C atoms), palmitic acid (16 C atoms), stearic acid (18 C atoms), and arachidic acid (20 C atoms).
Unsaturated Fatty Acids
- Fatty acid chains are non-linear; the molecules do not pack closely together
- Weak attractions (dispersion forces) between chains
- Lower melting points, hence are liquids at room temperature.
- Oleic acid and linoleic acid are examples.
Triacylglycerols
- Also known as triglycerides
- Major form of fatty acid storage in plants and animals
- Fats are solid at room temperature
- Oils are usually liquid at room temperature
Reactions (Metabolic)
- Fatty acids, when oxidized, decompose into smaller carbon molecules (C2 pieces) releasing CO2, water, and energy.
Reactions (Synthetic)
- Unsaturated fatty acids can be converted to saturated fatty acids through hydrogenation.
- Oxidation to decomposition is an easy process in unsaturated fatty acids and more difficult in saturated fatty acids
Saponification/Hydrolysis
- Treating triglycerides with a strong base (e.g., sodium hydroxide) breaks the ester bonds to produce glycerol and soap.
- Hydrolysis is the breakdown of a compound into other substances through the action of water.
Omega-3 Fatty Acids
- Mostly found in fish oils
- Contain mostly 20 and 22 carbons polyunsaturated fatty acids
- The first double bond is 3 carbons away from the omega end.
- Examples include EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), and Alpha linolenic acid
Cis vs Trans Fatty Acids
- Almost all natural unsaturated fatty acids have cis geometry in their double bonds.
- Small amounts of trans fatty acids are found in ruminating animals.
Cholesterol
- A steroidal alcohol.
- Found in animal fats and dairy products.
- Important component of cell membranes
- Can lead to atherosclerosis if levels are too high
Properties of Cholesterol
- Very insoluble in water
- Solid at room temperature.
- Compact, stiff, rigid structure
Cell Membrane Structure (Lipid Bilayer)
- A key structural component of cells
- Cholesterol participates in this structure.
Cholesterol Transport
- Cholesterol is not water-soluble; therefore, it is transported via lipoproteins.
- High-density lipoproteins (HDLs) transport cholesterol to the liver for removal ("good cholesterol").
- Low-density lipoproteins (LDLs) and very-low-density lipoproteins (VLDLs) can deposit cholesterol in arterial walls ("bad cholesterol").
Structural Features (HDL vs LDL)
- HDLs contain unsaturated cis fatty acids;
- LDLs contain more saturated and trans fatty acids.
- Both contain apolipoproteins and phospholipids.
Phospholipids
- Phospholipids are composed of polar heads and nonpolar tails for cell membranes.
- Phospholipids act like surfactants, which help solubilize fats in water.
- Lecithins are a type of phospholipid.
- Phospholipids are biosynthesized by humans from phosphatidic acids and fatty acids. ATP is also needed as a phosphorylating agent.
Waxes
- Fatty acid esters with long-chain alcohols.
- Used for waterproofing and other protective purposes by various organisms.
- Examples include beeswax, palm wax, and others.
Soaps & Detergents
- Soaps and detergents have nonpolar tails and polar heads.
- The nonpolar portion interacts with grease, facilitating removal.
- The polar portion interacts with water.
- Synthetic surfactants are categorized into anionic, nonionic, and cationic detergents.
Soaps in Hard Water
- Hard water contains high amounts of metal ions (Fe, Ca, Mg).
- These ions form insoluble salts with soap, resulting in a curd.
- Detergents function well in hard water because sulfonates are soluble in hard water.
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Description
Test your knowledge on the various types of lipids and fatty acids with this quiz. Explore questions about nutritional lipids, the characteristics of saturated vs unsaturated fatty acids, and the role of cholesterol in the body. Ideal for nutrition or biology students.
