Lipids Introduction: Dr. Abdah

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Where is a centre of asymmetry in triacylglycerols?

Carbon-4 of the glycerol backbone

Carbon-3 of the glycerol backbone

Carbon-1 of the glycerol backbone

Carbon-2 of the glycerol backbone (correct)

Which of the following is NOT a source of triacylglycerols?

Storage depots in adipocytes

Digestion of dietary carbohydrates (correct)

De novo synthesis in liver

Nomenclature of simple triacylglycerides

What is the difference between oils and fats?

Oils are derived from plants while fats are derived from animals

Oils are liquid at room temperature while fats are solid (correct)

Oils are solid at room temperature while fats are liquid

Oils contain saturated fatty acids while fats contain unsaturated fatty acids

Why do triacylglycerols release more energy when degraded compared to carbohydrates?

Because they are less oxidized Signup and view all the answers

What is a characteristic of triacylglycerols that helps prevent heat loss?

They are poor conductors of heat Signup and view all the answers

What is the major function of triacylglycerols in the body?

To store and transport fatty acids Signup and view all the answers

What is the composition of monoterpenes?

Composed of two isoprene units Signup and view all the answers

Which compound is a monoterpene found in the oil of geranium?

Geraniol Signup and view all the answers

What is the defining characteristic of steroids in terms of structure?

Has four tetracyclic rings Signup and view all the answers

Which compound is a carotenoid, known for its orange-colored pigment?

Squalene Signup and view all the answers

What is the main role of eicosanoids?

Inflammatory response Signup and view all the answers

Which compound is classified under isoprenoids and is a key component in Lipid vitamins?

Phosphoglycerides Signup and view all the answers

Which type of molecules are lipids?

Small molecules Signup and view all the answers

Which fatty acid is abundant and is commonly an important component of lipid molecules?

Myristic acid Signup and view all the answers

What type of interactions are involved in the association of lipid molecules?

Hydrogen bonds Signup and view all the answers

What makes fatty acids important metabolic fuels?

They yield more energy than proteins or carbohydrates Signup and view all the answers

Which types of fatty acids contain zero to three double bonds?

Saturated fatty acids Signup and view all the answers

What is the range of saturated fatty acids that have been found in nature?

C2 to C30 Signup and view all the answers

What is the main role of cholesterol in plasma membranes?

Maintaining membrane fluidity Signup and view all the answers

Which class of hormones does cholesterol serve as a precursor for?

Steroid hormones Signup and view all the answers

Which plant-derived compound is a time-honored stimulator of cardiac muscle contraction?

Cardiac glycosides Signup and view all the answers

What structural feature is common among all major human plasma lipoprotein classes?

Spherical shape Signup and view all the answers

What is the main function of plasma lipoproteins in mammals?

Transporting lipid molecules through the bloodstream Signup and view all the answers

What is the systematic name of the fatty acid with the numerical symbol 18:3(9,12,15)?

Cis,cis-9,12Octadecenoic Signup and view all the answers

Which lipid-soluble antioxidant molecules are found in plasma lipoproteins?

Alpha tocopherol Signup and view all the answers

Which fatty acid is the biosynthetic precursor of prostaglandins?

Arachidonic acid Signup and view all the answers

What is the trivial name for the compound with the systematic name cis-9-Hexadecenoic?

Palmitoleic Signup and view all the answers

In what biological fluid do prostaglandins act on smooth muscles?

Seminal fluid Signup and view all the answers

Which fatty acid is primarily found in the lipids of the nervous system?

Nervonic acid Signup and view all the answers

What is the numerical symbol for the fatty acid named Hexadecanoic with the trivial name Palmitic?

16:0 Signup and view all the answers

Study Notes

Lipids

Lipids are a group of naturally occurring compounds that are readily soluble in organic solvents such as hydrocarbons, chloroform, benzene, ethers, and alcohols.
They are water-insoluble organic molecules that are not polymers.
Lipids have a strong tendency to associate through noncovalent forces, including ionic bonds, hydrogen bonds, van der Waals forces, and hydrophobic interactions.

Classification of Lipids

Simple lipids: fatty acids, waxes, and triacylglycerols
Complex lipids: phospholipids, sphingolipids, isoprenoids, and lipoproteins

Fatty Acids

Fatty acids are monocarboxylic acids that contain hydrocarbon chains of variable lengths.
They are important components of several types of lipid molecules.
Fatty acids are important metabolic fuels, with the oxidation of fatty acids yielding more energy (37 kJ/g) than the oxidation of proteins or carbohydrates (16 kJ/g).
Common saturated fatty acids include:
- C16: palmitic acid (hexadecanoic acid)
- C18: stearic acid (octadecanoic acid)
Common unsaturated fatty acids include:
- C16:1: palmitoleic acid (cis-9-hexadecenoic acid)
- C18:1: oleic acid (cis-9-octadecenoic acid)
- C18:2: linoleic acid (cis,cis-9,12-octadecadienoic acid)
- C18:3: linolenic acid (cis,cis,cis-9,12,15-octadecatrienoic acid)
- C20:4: arachidonic acid (cis,cis,cis,cis-5,8,11,14-eicosatetraenoic acid)

Triacylglycerols

Triacylglycerols are composed of a glycerol moiety with each hydroxyl group esterified to a fatty acid.
They are the major storage and transport form of fatty acids.
Examples of triacylglycerols include:
- Tristearin (contains 3 residues of stearic acid)
- Tripalmitin (contains 3 residues of palmitic acid)
- Triolein (contains 3 residues of oleic acid)

Phospholipids

Phospholipids are complex lipids that contain a phosphate group and are amphipathic, meaning they have both hydrophobic and hydrophilic regions.
Examples of phospholipids include:
- Phosphatidic acid
- Sphingomyelin

Steroids

Steroids are complex derivatives of triterpenes that are composed of four fused rings.
They are distinguished from each other by the placement of carbon-carbon double bonds and various substituents.
Examples of steroids include:
- Cholesterol
- Steroid hormones (e.g. glucocorticoids, mineralocorticoids, androgens, estrogens, progestins)

Lipoproteins

Lipoproteins are any protein that is covalently linked to lipid groups.
They are found in blood plasma and transport lipid molecules through the bloodstream from one organ to another.
Examples of lipoproteins include:
- Chylomicron
- VLDL (very low-density lipoprotein)
- IDL (intermediate-density lipoprotein)
- LDL (low-density lipoprotein)
- HDL (high-density lipoprotein)

Eicosanoids

Eicosanoids are unsaturated fatty acids of 20 carbon atoms that contain 5-membered rings.
They are precursors of prostaglandins and other eicosanoids.
Examples of eicosanoids include:
- Arachidonic acid (20:4(n-6))
- Prostaglandins (e.g. PGA, PGB, PGD, PGE, PGF)

Terpenes

Terpenes are a class of lipids that are composed of isoprene units.
They are found in essential oils of plants and are classified based on the number of isoprene units they contain.
Examples of terpenes include:
- Monoterpenes (e.g. geraniol)
- Sesquiterpenes (e.g. farnesene)
- Diterpenes (e.g. phytol)
- Triterpenes (e.g. squalene)
- Tetraterpenes (e.g. carotenoids)
- Mixed terpenoids (e.g. vitamin E, ubiquinone, vitamin K)

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about the introduction to lipids as a group of naturally occurring compounds that are water-insoluble organic molecules. Understand the characteristics of lipids and how they differ from proteins, nucleic acids, and polysaccharides.