Fatty-Acids

What is Fatty Acids? Definition, Classification, Sources etc.

Fatty Acids

Fats are carboxylic acids with hydrocarbon chains (– CH2– CH2– CH2–) and are represented by a chemical formula R-COOH, where R stands for hydrocarbon chain.

The fatty acids are amphipathic in nature, i.e., each has hydrophilic (COOH) and hydrophobic (hydrocarbon chain) groups in the structure.

Classification of Fatty Acids

Fats are categorized into 4 significant classes:

  1. Straight chain fatty acids
  2. Branched-chain fatty acids
  3. Substituted fatty acids
  4. Cyclic fatty acids.

Classification-Fatty-A

Straight Chain Fatty Acids

Fatty acids, in which the carbons are organized linearly,are subclassified into 2 classes:

  1. Saturated fatty acids
  2. Unsaturated fatty acids
Saturated fatty acids

There is no double bond in the hydrocarbon chain of these fatty acids. Saturated fatty acids are subclassified into two classes:

  1. Even carbon acids bring even number of carbons, e.g., palmitic acid and stearic acid.
  2. Odd carbon acids carry odd number of carbons, e.g., propionic acid.
Unsaturated fatty acids

These contain double bonds in their hydrocarbon chains. These are subclassified according to the number of double bonds present in the structure as follows:

  1. Monoenoic or monounsaturated fatty acid
  2. Polyenoic or polyunsaturated fatty acid
  • Monoenoic or monounsaturated fats carry a single double bond in the molecule, e.g., oleic acid.
  • Polyenoic or polyunsaturated fats consist of two or more double bonds; for instance:
  • Dienoic acids have two double bonds, e.g., linoleic acid present in soyabean, sunflower, saffola and groundnut oil.
  • Trienoic acids have three double bonds, e.g., Linolenic acid present in poppyseed oil, linseed oil.
  • Tetraenoic acid with four double bonds, e.g., acid present in groundnuts.
Branched Chain Fatty Acids

These are less abundant than straight chain acids in animals and plants, e.g.

  • Isovaleric acid
  • Isobutyric acid
Substituted Fatty Acids

In substituted fatty acids one or more hydrogen atoms have been changed by another group, e.g.

– Lactic acid of blood

– Cerebronic acid and oxynervonic acids of brain glycolipids

– Ricinoleic acid of castor oil.

Cyclic Fatty Acids

Fatty acids bearing cyclic groups are present in some bacteria and seed lipids, e.g., hydnocarpic acid (Chaulmoogric acid) of chaulmoogra seed.

Numbering of Fatty Acid Carbon Atoms

Fatty acids carbon atoms are numbered beginning at the carboxyl terminus.Carbon atoms 2 and 3 are frequently referred to as a and ß respectively.The methyl carbon atom at the distal end of the chain is called omega (ω) carbon.

Carbon-Atoms

Representation of Double Bonds of Fatty Acids

Two systems are utilized to designate the position of double bond:

  • C-system
  • ω- or n-system
C-System

In C-system (i.e., C1 being the carboxyl carbon) the position of double bond is represented by the signΔ(delta), followed by a superscript number. For instance, oleic acid is a C18 fat with one double bond in between carbon number 9 and 10 is represented as C: 18:1Δ9.

ω– or n- System

In this system, ‘ω’ or ‘n’ describes the carbon of their terminal methyl group in a fat. Inω- system or n-system, the oleic acid is denoted as C: 18:1:ω -9to indicate that:

  • ω -9 represents the double bond position which is present in between 9th and 10th carbon atoms, the first carbon atom being that of the terminal methyl group. This technique is widely utilized by nutritionists. Naturally taking place unsaturated fats belong toω -9,ω -6 andω -3 series. For instance,
  • ω -9: Oleic acid (C: 18:1:ω -9).
  • ω -6: Linoleic acid (C: 18:2:ω -6).
  • Arachidonic acid (C: 20:4:ω -6).
  • ω-3: Linolenic acid (C: 18:3:ω -3).
Further Reading:  Covalent Bond, Types, Polar and Non-polar Bond
Sources of Fatty Acids

Almost all foods contain many different fats, consisting of saturated-, monounsaturated- and polyunsaturated omega-6 and omega-3 fatty acids. However, the amount of the various fatty acids varies from one food to another, making it possible to alter the intake of fatty acids by changing foods. These are the typical sources of fatty acids.

  • Milk and milk items; such as butter, cream, ice cream, sour cream, yoghurt, cheese and more.
  • Red meat and products made from red meat.
  • Coconut and coconut oil.
  • Avocado and products made from avocado.
  • Numerous nuts such as almonds, peanuts and brazil nuts.
  • Wheat and products made from wheat.
Functions of Fatty Acids

Fatty acids have three major physiological functions.

  1. They work as building blocks of phospholipids and glycolipids. These amphipathic molecules are essential components of biological membranes.
  2. Fat derivatives function as hormones, e.g., prostaglandins.
  3. Fats function as a significant fuel for many cells.

The industrial uses are:

  1. Fats are primarily used in the production of soap, both for cosmetic purposes and, in the case of metallic soaps, as lubricants. Fats are also converted, by means of their methyl esters, to fatty alcohols and fatty amines, which are precursors to surfactants, detergents, and lubricants.
  2. Other applications include their use as emulsifiers, texturizing agents, moistening agents, anti-foam agents, or stabilizing agents.

 

MCQs with Answers: Fatty Acids

  1. What is the chemical formula for fats representing the hydrocarbon chain?
    • A) R-CH2
    • B) R-COOH
    • C) R-OH
    • D) R-CH3

    Answer: B) R-COOH

  2. What term describes the amphipathic nature of fatty acids?
    • A) Hydrophilic
    • B) Hydrophobic
    • C) Amphiphilic
    • D) Bipolar

    Answer: C) Amphiphilic

  3. How many major classes are fats categorized into?
    • A) 2
    • B) 3
    • C) 4
    • D) 5

    Answer: C) 4

  4. Which subclass of straight-chain fatty acids contains double bonds in the hydrocarbon chain?
    • A) Saturated fatty acids
    • B) Unsaturated fatty acids
    • C) Branched-chain fatty acids
    • D) Substituted fatty acids

    Answer: B) Unsaturated fatty acids

  5. What type of fatty acids have no double bonds in the hydrocarbon chain?
    • A) Polyunsaturated fatty acids
    • B) Saturated fatty acids
    • C) Monounsaturated fatty acids
    • D) Branched-chain fatty acids

    Answer: B) Saturated fatty acids

  6. Which fatty acid subclass consists of oleic acid?
    • A) Polyenoic fatty acids
    • B) Monoenoic fatty acids
    • C) Branched-chain fatty acids
    • D) Even carbon fatty acids

    Answer: B) Monoenoic fatty acids

  7. What is the main characteristic of polyenoic or polyunsaturated fats?
    • A) Single double bond
    • B) Two or more double bonds
    • C) Branched structure
    • D) Even number of carbons

    Answer: B) Two or more double bonds

  8. Which system uses the sign Δ to designate the position of a double bond in a fatty acid?
    • A) ω- or n-system
    • B) C-system
    • C) δ-system
    • D) β-system

    Answer: B) C-system

  9. How is the position of a double bond represented in the ω- or n-system?
    • A) Δ followed by a superscript number
    • B) Ω followed by a subscript number
    • C) ω followed by a superscript number
    • D) δ followed by a subscript number

    Answer: C) ω followed by a superscript number

  10. Where does numbering of fatty acid carbon atoms begin?
    • A) Hydrocarbon terminus
    • B) Methyl terminus
    • C) Carboxyl terminus
    • D) Omega terminus

    Answer: C) Carboxyl terminus

  11. What are the physiological functions of fatty acids?
    • A) Building blocks of nucleotides
    • B) Precursors to enzymes
    • C) Building blocks of phospholipids and glycolipids
    • D) Structural components of carbohydrates

    Answer: C) Building blocks of phospholipids and glycolipids

  12. What is the primary fuel function of fats?

    Answer: C) Energy storage

  13. In industrial uses, what are fats primarily converted into for soap production?
    • A) Fatty alcohols
    • B) Fatty amines
    • C) Fatty acids
    • D) Fatty esters

    Answer: A) Fatty alcohols

  14. Which term describes the ability of fats to function as emulsifiers, detergents, and lubricants?
    • A) Moistening agents
    • B) Amphiphilic properties
    • C) Hydrophilic nature
    • D) Surfactants

    Answer: D) Surfactants

  1. What term is used to describe fatty acids with a single double bond in the molecule?
    • A) Monoenoic
    • B) Polyenoic
    • C) Saturated
    • D) Branched

    Answer: A) Monoenoic

  2. Which of the following is an example of a trienoic fatty acid?
    • A) Linoleic acid
    • B) Oleic acid
    • C) Linolenic acid
    • D) Palmitic acid

    Answer: C) Linolenic acid

  3. In the C-system, how is the position of a double bond represented?
    • A) Ω followed by a superscript number
    • B) Δ followed by a superscript number
    • C) α followed by a subscript number
    • D) β followed by a subscript number

    Answer: B) Δ followed by a superscript number

  4. What is the methyl carbon atom at the distal end of the fatty acid chain called?
    • A) Alpha (α) carbon
    • B) Beta (β) carbon
    • C) Gamma (γ) carbon
    • D) Omega (ω) carbon

    Answer: D) Omega (ω) carbon

  5. Which fatty acids are less abundant in animals and plants compared to straight-chain fatty acids?
    • A) Saturated fatty acids
    • B) Branched-chain fatty acids
    • C) Unsaturated fatty acids
    • D) Substituted fatty acids

    Answer: B) Branched-chain fatty acids

  6. What is the unit of measurement for dipole moments of simple heteronuclear diatomic molecules?
    • A) Coulomb/meter (C/m)
    • B) Ampere (A)
    • C) Debye (D)
    • D) Farad (F)

    Answer: C) Debye (D)

  7. What does the dipole moment provide information about in molecular structure?
    • A) Atomic mass
    • B) Bond strength
    • C) Percentage ionic character
    • D) Electron configuration

    Answer: C) Percentage ionic character

Further Reading:  Alkenes: Structure, Physical Characteristics, and Uses of Alkenes

 

FAQs related to Fatty Acids

1. What are fatty acids?

  • Fats are carboxylic acids with hydrocarbon chains, represented by the chemical formula R-COOH, where R stands for a hydrocarbon chain.

2. How are fatty acids classified?

  • Fats are categorized into four significant classes: straight chain fatty acids, branched-chain fatty acids, substituted fatty acids, and cyclic fatty acids.

3. What is the distinction between saturated and unsaturated fatty acids?

  • Saturated fatty acids have no double bonds in the hydrocarbon chain, while unsaturated fatty acids contain double bonds.

4. Can you provide examples of polyenoic fatty acids?

  • Yes, polyenoic fatty acids consist of dienoic acids with two double bonds, trienoic acids with three double bonds, and tetraenoic acids with four double bonds.

5. Which fatty acids have a single double bond in the molecule?

  • Monoenoic or monounsaturated fatty acids carry a single double bond in the molecule, such as oleic acid.

6. What are branched-chain fatty acids?

  • Branched-chain fatty acids are less abundant than straight-chain acids in animals and plants, and examples include isovaleric acid and isobutyric acid.

7. How are double bond positions represented in the C-system?

  • In the C-system, the position of a double bond is represented by the sign Δ (delta), followed by a superscript number.

8. What does ω or n in the ω- or n-system signify?

  • In the ω- or n-system, ω or n represents the carbon of the terminal methyl group in a fat.

9. What are common sources of fatty acids?

  • Common sources of fatty acids include milk and milk products, red meat, coconut and coconut oil, avocado, various nuts, and wheat and its products.

10. What functions do fatty acids serve in the body?

  • Fatty acids serve as building blocks of phospholipids and glycolipids in biological membranes, function as hormones (e.g., prostaglandins), and serve as a significant fuel for many cells.

11. What are the industrial uses of fats?

  • Fats are used in the production of soap, as lubricants, and can be converted to fatty alcohols and amines for the production of surfactants, detergents, and lubricants.

 

Further Reading:  Determination of the Rate of a Chemical Reaction

Summary

The tutorial on Fatty Acids delves into the definition, classification, sources, and functions of these essential compounds. Fatty acids, characterized by amphipathic nature, consist of hydrophilic (COOH) and hydrophobic (hydrocarbon chain) groups. They are classified into straight-chain, branched-chain, substituted, and cyclic fatty acids.

Straight chain fatty acids are further categorized into saturated and unsaturated types, with unsaturated fatty acids containing double bonds. Polyenoic fatty acids, such as dienoic and trienoic acids, exemplify multiple double bonds. Branched-chain fatty acids, like isovaleric acid, exhibit less abundance in animals and plants.

The tutorial explores substituted fatty acids, where hydrogen atoms are replaced by other groups, and cyclic fatty acids found in bacteria and seed lipids. Additionally, it covers the numbering of fatty acid carbon atoms and the representation of double bonds using C-system and ω- or n-system.

Understanding the dietary sources of fatty acids is crucial, and the tutorial lists common foods containing saturated, monounsaturated, and polyunsaturated omega-6 and omega-3 fatty acids. Fatty acids serve pivotal roles as building blocks of biological membranes, hormones (e.g., prostaglandins), and a significant fuel for cells.

The summary concludes with insights into the industrial applications of fats, highlighting their use in soap production, lubricants, and conversion to fatty alcohols and amines for surfactants, detergents, and lubricants. Overall, the tutorial provides a comprehensive overview of fatty acids, elucidating their biochemical, nutritional, and industrial significance.