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Questions and Answers
What are triacylglycerols primarily composed of?
What are triacylglycerols primarily composed of?
Waxes are simple lipids that consist of esters of long-chain fatty acids and alcohols.
Waxes are simple lipids that consist of esters of long-chain fatty acids and alcohols.
True
Name two types of complex lipids.
Name two types of complex lipids.
Phospholipids and Sphingophospholipids
Fatty acids are carboxylic acids containing carbon, hydrogen, and oxygen in the proportions of _____%, _____%, and _____% respectively.
Fatty acids are carboxylic acids containing carbon, hydrogen, and oxygen in the proportions of _____%, _____%, and _____% respectively.
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Match the following types of lipids to their characteristics:
Match the following types of lipids to their characteristics:
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Which of the following is NOT a function of waxes?
Which of the following is NOT a function of waxes?
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Saturated fatty acids contain one or more double bonds.
Saturated fatty acids contain one or more double bonds.
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What is the primary structural function of phospholipids in biological systems?
What is the primary structural function of phospholipids in biological systems?
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Which fatty acid is classified as a saturated fatty acid?
Which fatty acid is classified as a saturated fatty acid?
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All unsaturated fatty acids have at least one double bond in their structure.
All unsaturated fatty acids have at least one double bond in their structure.
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What is the trivial name for the fatty acid with the formula 18:2 Δ9,12?
What is the trivial name for the fatty acid with the formula 18:2 Δ9,12?
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The melting point of __________ acid is -5.00°C.
The melting point of __________ acid is -5.00°C.
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Match the following fatty acids with their classification:
Match the following fatty acids with their classification:
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Which factor increases the melting point of fatty acids?
Which factor increases the melting point of fatty acids?
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Cis configuration is the most common form of double bonds found in naturally occurring unsaturated fatty acids.
Cis configuration is the most common form of double bonds found in naturally occurring unsaturated fatty acids.
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What is the general effect of double bonds on the solubility of fatty acids?
What is the general effect of double bonds on the solubility of fatty acids?
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Phospholipids can help in the removal of cholesterol from the body.
Phospholipids can help in the removal of cholesterol from the body.
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What are the main structural components of cell membranes?
What are the main structural components of cell membranes?
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Lipids are soluble in __________ solvents like ether and chloroform.
Lipids are soluble in __________ solvents like ether and chloroform.
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Match the types of lipids with their primary functions:
Match the types of lipids with their primary functions:
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Essential fatty acids are important because they:
Essential fatty acids are important because they:
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What are the detrimental effects of fat accumulation in the liver?
What are the detrimental effects of fat accumulation in the liver?
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Lipids are mainly water-soluble bio-molecules.
Lipids are mainly water-soluble bio-molecules.
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Study Notes
Biomolecules - Lipids
- Lipids are a diverse group of fat-like substances, acting as concentrated energy stores.
- They are water-insoluble but soluble in organic solvents like ether, benzene, and chloroform.
- Lipids are esters of long-chain fatty acids and alcohols.
- They function as fuel, signaling molecules, and components of membranes, hormones and intracellular messengers.
- Lipids insulate, protect internal organs, and contribute to the body's shape and smoothness.
- Phospholipids prevent fat accumulation in the liver.
Lipid Function in Cells
- Lipids build cell membranes, regulating permeability.
- Vitamins K and Q are coenzymes crucial for blood clotting and ATP production respectively in cells.
- Paracrine hormones act locally affecting specific cellular processes.
- Steroid hormones affect the whole body.
- Growth factor molecules stimulate cell division and growth.
- Pigments like those in tomatoes, carrots, pumpkins and some birds impart color.
- Some lipids act as antioxidants.
Classification of Lipids
- Storage Lipids: These include fats and oils (triacylglycerols), the body's primary energy source. Waxes also fall under this category.
- Structural Lipids: Building blocks of biological membranes (phospholipids, sphingolipids).
- Derived Lipids: Formed through hydrolysis of simple and complex lipids like alcohols, fatty acids, and steroid hormones. They also include ketone bodies and hydrocarbons.
- Miscellaneous Lipids: These encompass compounds with varied characteristics, including squalene, terpenes, hydrocarbons, and carotenoids.
Triacylglycerol (TAG)
- TAGs are esters of glycerol with three fatty acids.
- They are hydrophobic and insoluble in water.
- TAGs function as energy storage molecules.
- Adipocytes (fat cells) store TAGs in animals, and endosperm and cotyledon cells in plants.
- Mammals store approximately 85-95% of their dietary storage lipids as TAGs.
Basic Phospholipid Structure
- Phospholipids form a bilayer structure critical to cell membranes.
- The hydrophilic head groups face the aqueous environment.
- The hydrophobic tails are positioned inwards, facing each other.
- These components are essential for the fluidity of the membrane.
Wax
- Waxes are esters of long-chain fatty acids with long-chain alcohols.
- They act as storage compounds, preventing water loss in plants, and as protective coatings for skin and hair in various organisms.
Fatty Acids
- Fatty acids consist of carbon, hydrogen, and oxygen atoms.
- They are carboxylic acids with hydrocarbon chains varying in length (4 to 36 carbons).
- Fatty acids are categorized into saturated and unsaturated.
- Saturated fatty acids lack double bonds and have higher melting points; unsaturated fatty acids have one or more double bonds and have lower melting points.
Physical Properties of Fatty Acids
- The length and unsaturation of the hydrocarbon chain determine their physical properties like melting point and water solubility.
- Longer chains, lower unsaturation, and higher melting points; shorter chains, higher unsaturation and lower melting points.
- The presence of double bonds lowers the melting point of fatty acids.
- Trivial names of fatty acids link them to natural sources like seed oils.
Nomenclature of Fatty Acids
- Fatty acids are named according to the number of carbon atoms and the presence of double bonds.
- No double bonds are marked with a ':0'.
- One double bond is marked as ':1'.
- Multiple double bonds are indicated thusly '20:4'.
Types of Compound Lipids
- Phosphoglycerides: This class includes phosphatidylcholine (lecithin), phosphatidylethanolamine (cephalin), phosphatidylinositol, and phosphatidylserine.
- Sphingolipids: Sphingomyelins, cerebrosides, and gangliosides are major examples.
- Cholesterol: A crucial component of animal cell membranes, precursor for steroid hormones, and involved in bile acid synthesis.
Lipoproteins
- HDL (High-Density Lipoproteins): Transport cholesterol from tissues to the liver. Often referred to as 'good' cholesterol.
- LDL (Low-Density Lipoproteins): Transport cholesterol from the liver to the tissues. Often referred to as 'bad' cholesterol.
- VLDL (Very Low-Density Lipoproteins): Transport triglycerides from the liver to the tissues. Often referred to as a type of chylomicron.
Effect of Fats on Blood
- Saturated fats raise total and LDL ('bad') cholesterol levels.
- Polyunsaturated fats lower total and LDL cholesterol, but might slightly reduce HDL cholesterol ('good').
- Monounsaturated fats are often linked to lower LDL cholesterol while raising HDL cholesterol.
- Trans fats raise total and LDL ('bad') cholesterol, and lower HDL ('good') cholesterol.
- Omega-3 fats lower total and LDL cholesterol and increase HDL cholesterol.
Atherosclerosis
- The build-up of plaque (cholesterol and other substances) in the arteries causing gradual narrowing.
- Leads to increased risk of heart attack or stroke.
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Description
This quiz covers the essential functions and characteristics of lipids, a vital class of biomolecules. Explore their roles in energy storage, cell membrane composition, and hormonal signaling. Understand how lipids contribute to various cellular processes and overall body functions.
