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Questions and Answers
A monoterpene contains 10 carbons and has three isoprene units.
A monoterpene contains 10 carbons and has three isoprene units.
False
Terpenes are classified based on the number of isoprene units they contain.
Terpenes are classified based on the number of isoprene units they contain.
True
All terpenes are synthesized from glucose and fatty acids.
All terpenes are synthesized from glucose and fatty acids.
False
Steroids have a structure consisting of three six-membered rings and one five-membered ring.
Steroids have a structure consisting of three six-membered rings and one five-membered ring.
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Both SN1 and E1 processes are involved in terpene formation mechanisms.
Both SN1 and E1 processes are involved in terpene formation mechanisms.
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A tetraterpene contains 40 carbons and has six isoprene units.
A tetraterpene contains 40 carbons and has six isoprene units.
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The biosynthesis of terpenes is inefficient because different reactions are required for each compound.
The biosynthesis of terpenes is inefficient because different reactions are required for each compound.
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Isoprene units are found in the structure of certain terpenes and can be identified using a four-carbon chain with a one-carbon branch.
Isoprene units are found in the structure of certain terpenes and can be identified using a four-carbon chain with a one-carbon branch.
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Steroids typically have a rigid structure where all four rings lie in the same plane due to their all trans arrangement.
Steroids typically have a rigid structure where all four rings lie in the same plane due to their all trans arrangement.
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Cis-decalin has its two fused rings lying roughly in the same plane.
Cis-decalin has its two fused rings lying roughly in the same plane.
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Cholesterol is synthesized in the human body from squalene (C30), and does not need to be ingested.
Cholesterol is synthesized in the human body from squalene (C30), and does not need to be ingested.
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Trans arrangements of fused rings are always higher in energy than their cis counterparts.
Trans arrangements of fused rings are always higher in energy than their cis counterparts.
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Cholesterol has eight stereogenic carbons and can theoretically exist in 256 different stereoisomer forms.
Cholesterol has eight stereogenic carbons and can theoretically exist in 256 different stereoisomer forms.
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The two angular methyl groups in steroids are typically oriented parallel to the plane of the molecule.
The two angular methyl groups in steroids are typically oriented parallel to the plane of the molecule.
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The primary action of cholesterol-lowering drugs is to enhance cholesterol synthesis in the liver.
The primary action of cholesterol-lowering drugs is to enhance cholesterol synthesis in the liver.
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Synthetic analogues of natural steroids have no significant applications in medicine.
Synthetic analogues of natural steroids have no significant applications in medicine.
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Terpenes can only be formed as acyclic structures with no branch points.
Terpenes can only be formed as acyclic structures with no branch points.
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Isoprene units, which are the building blocks of terpenes, consist of a chain of four carbons with a one-carbon branch on a middle carbon.
Isoprene units, which are the building blocks of terpenes, consist of a chain of four carbons with a one-carbon branch on a middle carbon.
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The classification of terpenes does not include variations based on the number of isoprene units present.
The classification of terpenes does not include variations based on the number of isoprene units present.
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Cis-trans isomerism can occur in terpenes due to the presence of double bonds in their structures.
Cis-trans isomerism can occur in terpenes due to the presence of double bonds in their structures.
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The structure of steroids is primarily derived from terpene biosynthesis processes.
The structure of steroids is primarily derived from terpene biosynthesis processes.
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Biosynthesis of terpenes involves multiple enzymatic reactions that form isoprene units.
Biosynthesis of terpenes involves multiple enzymatic reactions that form isoprene units.
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All terpenes are structurally identical and share the same functions in biological systems.
All terpenes are structurally identical and share the same functions in biological systems.
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The carbon arrangement in terpenes can affect their pharmacological properties and interactions in biological systems.
The carbon arrangement in terpenes can affect their pharmacological properties and interactions in biological systems.
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Study Notes
Lipids
- Lipids are biomolecules soluble in organic solvents.
- Their identity is based on physical properties, not functional groups.
- They share properties with hydrocarbons, containing many C-C and C-H bonds.
- Hydrolyzable lipids can be broken down by hydrolysis with water.
- Many hydrolyzable lipids contain an ester unit.
- Examples include waxes, triacylglycerols, and phospholipids.
- Nonhydrolyzable lipids cannot be broken down by aqueous hydrolysis.
- Examples include fat-soluble vitamins, eicosanoids, terpenes, and steroids.
Waxes
- Waxes are esters formed from high molecular weight alcohols and fatty acids.
- Lanolin, a wax, coats wool fibers.
- Spermaceti wax, found in sperm whales, is largely CH3(CH2)14COO(CH2)15CH3.
Triacylglycerols (Triglycerides)
- Triacylglycerols are triesters that produce glycerol and three fatty acids upon hydrolysis.
- Simple triacylglycerols have three identical fatty acids.
- Mixed triacylglycerols have two or three different fatty acids.
Fatty Acids in Triacylglycerols
- Fatty acids in triacylglycerols are typically 12-20 carbons long.
- Saturated fatty acids have no C=C double bonds.
- Unsaturated fatty acids have one or more C=C double bonds.
- Double bonds in naturally occurring fatty acids have the Z configuration.
- The melting point of a fatty acid is inversely related to the degree of unsaturation.
- Common saturated fatty acids include lauric, myristic, palmitic, stearic, and arachidic acids.
- Common unsaturated fatty acids include palmitoleic, oleic, linoleic, linolenic, and arachidonic acids.
Fats vs. Oils
- Fats are typically solid at room temperature.
- Oils are typically liquid at room temperature.
- Fats have a higher percentage of saturated fatty acids and are generally of animal origin.
- Oils have a higher percentage of unsaturated fatty acids and are generally of vegetable origin.
Phospholipids
- Phospholipids are hydrolyzable lipids containing a phosphorus atom.
- Common types include phosphoacylglycerols and sphingomyelins.
- They're major components of cell membranes.
- Phospholipids are organic derivatives of phosphoric acid.
- The remaining OH group on phosphorus typically has a negative charge.
Phosphoacylglycerols (Phosphoglycerides)
- Phosphoacylglycerols are the second most abundant type of lipid.
- They're major components of cell membranes.
- Their structure resembles triacylglycerols with only two of the hydroxy groups esterified with fatty acids.
- The third OH group is part of a phosphodiester bonded to a low-molecular-weight alcohol.
- Two main types are phosphatidylethanolamine (cephalin) and phosphatidylcholine (lecithin).
- The middle carbon of glycerol is stereogenic.
Sphingomyelins
- Sphingomyelins are derivatives of sphingosine.
- They have a phosphodiester at C1 and an amide formed with a fatty acid at C2.
- They are major components of the myelin sheath surrounding nerve cells.
Hydrolysis of Triacylglycerols
- Hydrolysis cleaves the three ester units from the triacylglycerol.
- The products are glycerol and three fatty acids.
Hydrogenation and Oxidation
- Hydrogenation converts a liquid oil into a solid fat.
- Oxidation can occur at allylic carbons.
- Oxidation products are unstable and leads to rancidity.
Energy Storage in Lipids
- Triacylglycerols are the primary form of energy storage in the body.
- Complete oxidation yields CO2, H2O, and a large amount of energy.
Fat-Soluble Vitamins
- Fat-soluble vitamins are a group of organic compounds needed in small amounts.
- They must be obtained from the diet.
- Examples are vitamins A, D, E, and K.
- Excess vitamins are stored in fat cells.
Fat-Soluble Vitamins (A and D)
- Vitamin A (retinol) is synthesized from beta-carotene.
- It is essential for vision and mucous membrane health.
- Vitamin D3 is not a true vitamin, but is synthesized from cholesterol.
- It regulates calcium and phosphorus metabolism.
Fat-Soluble Vitamins (E and K)
- Vitamin E (alpha-tocopherol) is an antioxidant.
- Vitamin K is essential for blood clotting.
Eicosanoids
- Eicosanoids are potent biological compounds derived from arachidonic acid.
- Examples include prostaglandins, thromboxanes, prostacyclins, and leukotrienes.
- Eicosanoids are local mediators acting as hormones in the body.
Use of Prostaglandins
- Prostaglandins, such as Dinoprostone (PGE2), have clinical uses.
- They can be used to induce labor or terminate pregnancies.
- Prostaglandin analogs are used due to prostaglandin instability.
Synthetic Hormone Steroids
- Steroid analogs can be used as oral contraceptives.
- Synthetic androgen analogs, called anabolic steroids, promote muscle growth but use is not permitted in competitive sports.
Adrenal Cortical Steroids
- Adrenal cortical steroids, such as cortisone, cortisol, and aldosterone, are synthesized in the adrenal glands.
- Cortisone and cortisol are anti-inflammatory agents and regulate carbohydrate metabolism.
- Aldosterone regulates blood pressure by controlling Na+ and K+ concentration in body fluids.
Terpenes
- Terpenes are lipids composed of repeating isoprene units.
- Isoprene units have five carbons.
- Terpenes can be cyclic or acyclic, and may contain heteroatoms.
- Examples include myrcene, menthol, and limonene.
Terpene Biosynthesis
- Terpenes are synthesized from dimethylallyl diphosphate and isopentenyl diphosphate.
- The same reaction is used repeatedly to synthesize progressively more complex compounds.
Steroids
- Steroids are tetracyclic lipids with diverse biological activity.
- Steroids consist of three 6-membered rings and one 5-membered ring.
Cholesterol
- Cholesterol is an essential steroid.
- It is essential for cell membranes and is a precursor for other steroids.
- Cholesterol is synthesized in the body from squalene.
Cholesterol-Lowering Drugs
- Drugs like atorvastatin (Lipitor) and simvastatin (Zocor) block cholesterol synthesis early.
Steroidal Sex Hormones
- Steroid hormones regulate secondary sex characteristics.
- Estrogens (estradiol, estrone) control the menstrual cycle.
- Progesterone is important in pregnancy.
- Androgens (testosterone, androsterone) control male characteristics.
### Identifying Isoprene Units in Terpenes
- Identify four-carbon chains with one-carbon branches.
- Each five-carbon unit is one isoprene unit.
Classification of Terpenes
- Terpenes are classified by the number of isoprene units they contain.
- Monoterpenes (10 carbons, 2 units)
- Sesquiterpenes (15 carbons, 3 units)
- Diterpenes (20 carbons, 4 units), etc.
3D Structure of Steroids
- Steroid rings are usually arranged in a planar, all-trans arrangement.
3D Structure of Phosphoacylglycerols
- Phosphoacylglycerols (phosphoglycerides) have a polar head and two nonpolar tails extending from the glycerol backbone.
- Tails are typically long-chain fatty acids.
### NSAIDS
- NSAIDs (Nonsteroidal Anti-inflammatory Drugs) inhibit prostaglandin synthesis.
- Inactivating COX-1 and COX-2 enzymes causes increased gastric secretions.
- COX-2 inhibitors are specifically targeted to block COX-2, leading to less or no gastric issues.
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Description
This quiz covers the essential concepts related to lipids, focusing on waxes and triacylglycerols. You'll explore the properties, types, and examples of these biomolecules. Test your understanding of hydrolyzable and nonhydrolyzable lipids, along with their significance in biology.
