Fatty Acids

Fatty acids, along with glycerol, are building blocks of lipids in our bodies and food. The first thing that comes to your mind when you read fatty acids may be that they are fat or made of fat. They are, in fact, the building blocks of fats and other lipids such as waxes. The structure of fatty acids allows for the different types to emerge: saturated and unsaturated fatty acids. 

Get started Sign up for free
Fatty Acids Fatty Acids

Create learning materials about Fatty Acids with our free learning app!

  • Instand access to millions of learning materials
  • Flashcards, notes, mock-exams and more
  • Everything you need to ace your exams
Create a free account

Millions of flashcards designed to help you ace your studies

Sign up for free

Convert documents into flashcards for free with AI!

Table of contents

    Fatty acids are acids belonging to the carboxylic acid group, meaning they consist of a carboxyl group ⎼COOH (carbon-oxygen-hydrogen).

    The structure of fatty acids

    Fatty acids are, like the lipids that they build, organic molecules. This means they contain carbon and hydrogen. They contain oxygen as well.

    They are often referred to as long molecules, as they consist of a long, straight chain of carbon and hydrogen atoms, with a carboxyl acid group (―COOH) at one end and a methyl group -CH3 at the other. The simple formula is RCOOH, where R is the hydrocarbon chain, including the methyl group. The R-group may be saturated or unsaturated.

    In addition, fatty acids can vary in terms of the length of the hydrocarbon chain (12 to 20 carbon atoms).

    The sheer length of the hydrocarbon chain means that there are many carbon and hydrogen atoms but far fewer oxygen atoms as a part of the COOH. This makes these fatty acids hydrophobic.

    The two types of fatty acids

    There are two different types of fatty acids: saturated and unsaturated.

    Saturated fatty acids

    Saturated fatty acids have only single bonds between carbon atoms in the hydrocarbon chain. As you already know, carbon can form four bonds with other atoms. You also know that the hydrocarbon chain is composed of carbon atoms, to which hydrogen atoms attach. They attach to two of the four bonds of carbon atoms. This means that there are a lot of hydrogen atoms attached to each carbon, so you can say that there is a maximum number of hydrogen atoms in the chain and that the fatty acid is saturated with hydrogen.

    Saturated fatty acids are primarily present in food and products from animal sources, such as beef, lamb, butter, cream, etc., and oils derived from plant sources, such as coconut and palm oil.

    They are solid at room temperature because the hydrocarbon chain is straight, which in turn allows molecules of saturated fatty acids to pack closely together.

    The most common saturated fatty acid is palmitic acid.

    Fatty Acids, Chemical structure of isopalmitic acid saturated fatty acid, StudySmarterFig. 1 - Simplified chemical structure of isopalmitic acid, a saturated fatty acid. It consists of single bonds between carbon and hydrogen atoms in the long hydrocarbon chain

    Unsaturated fatty acids

    Unsaturated fatty acids have single bonds between carbon atoms but double bonds as well. As there are double bonds between some carbon atoms in the hydrocarbon chain, not as many hydrogen atoms can attach to carbon atoms. So you can say that these fatty acids are not saturated or unsaturated with hydrogen.

    Double bonds make them liquid at room temperature. As they cause the molecule to bend, they prevent unsaturated fatty acids from packing together as closely as saturated fatty acids.

    Depending on how many double bonds are present, there are two different types: mono-unsaturated and poly-unsaturated.

    Mono-unsaturated fatty acids

    Mono-unsaturated fatty acids have only one double bond between two carbon atoms in the hydrocarbon chain.

    Fatty Acids, Chemical structure of lumequeic acid monounsaturated fatty acid, StudySmarterFig. 2 - Simplified chemical structure of lumequeic acid, a mono-unsaturated fatty acid. It consists of single bonds between carbon and hydrogen atoms but one double bond as well

    Poly-unsaturated fatty acids

    Poly-unsaturated fatty acids have two or more double bonds between carbon atoms in the hydrocarbon chain.

    Fatty Acids, Chemical structure of colneleic acid polyunsaturated fatty acid, StudySmarterFig. 3 - Simplified structure of colneleic acid, a poly-unsaturated fatty acid. It consists of two or more double bonds in the hydrocarbon chain

    Essential fatty acids

    In your lipids and fatty acids studies, you will undoubtedly come across essential fatty acids. They are called essential because they are extremely important for our health, especially the heart and the brain, but they cannot be synthesized (made) by our body. Therefore, we need to consume food high in essential fats: fish and other seafood, seeds such as hemp and pumpkin seeds, leafy vegetables, etc.

    In humans, there are two: alpha-linolenic acid or ALA and linoleic acid or LA.

    ALA is an omega-3, while LA is an omega-6 fatty acid. Both are poly-unsaturated.

    Two other omega-3 acids are of great importance for our bodies: eicosapentaenoic (EPA) and docosahexaenoic (DHA). Our bodies can produce these by converting the ALA but in a very limited amount.

    The names are quite complicated, and you are not required to learn them by heart. They are mentioned here only to familiarise you with the acronyms ALA, LA, EPA, and DHA.

    You may wonder why these acids are called omega-3 and omega-6. This is because, in the long hydrocarbon chain, the carbon atoms are numbered 1, 2, 3, etc. They are numbered starting from the end that has the methyl group. The last letter of the Greek alphabet, the omega (ω), is used to indicate the double bonds in the chain.

    The similarities and differences between saturated and unsaturated fatty acids

    Fatty AcidsSaturatedUnsaturated
    mono-unsaturatedpoly-unsaturated
    StructureLong hydrocarbon chain with a methyl group + a carboxyl group = RCOOHLong hydrocarbon chain with a methyl group + a carboxyl group = RCOOHLong hydrocarbon chain with a methyl group + a carboxyl group = RCOOH
    Hydrocarbon chainstraightbentbent
    Bondssingle bondsone double bondmultiple double bonds
    State at room temperaturesolidliquidliquid
    Visual of the structure

    Figure 1

    Figure 2

    Figure 3

    Fatty Acids - Key takeaways

    • Fatty acids are, along with glycerol, building blocks of lipids.

    • Fatty acids consist of a long, straight chain of carbon and hydrogen atoms, with a carboxyl acid group (―COOH) at one end and a methyl group CH3 at the other. The simple formula is RCOOH, where R is the hydrocarbon chain. The R-group may be saturated or unsaturated.

    • Saturated fatty acids have only single bonds between carbon atoms in the hydrocarbon chain. These acids are solid at room temperature. A straight hydrocarbon chain allows for them to pack together closely.

    • Unsaturated fatty acids have single bonds between carbon atoms but double bonds as well. They are liquid at room temperature due to the bend in the hydrocarbon chain caused by double bonds.

    • Mono-unsaturated fatty acids have only one double bond between two carbon atoms in the hydrocarbon chain. Poly-unsaturated fatty acids have two or more double bonds between carbon atoms in the hydrocarbon chain.

    • Essential fatty acids are extremely important for our health, especially the heart and the brain, but they cannot be synthesised (made) by our body. Alpha-linolenic acid or ALA and linoleic acid or LA are essential fatty acids. ALA is an omega-3, while LA is an omega-6 fatty acid.

    Fatty Acids Fatty Acids
    Learn with 0 Fatty Acids flashcards in the free StudySmarter app

    We have 14,000 flashcards about Dynamic Landscapes.

    Sign up with Email

    Already have an account? Log in

    Frequently Asked Questions about Fatty Acids

    What is the structure of a fatty acid?

    Fatty acids consist of a long, straight chain of carbon and hydrogen atoms, with a carboxyl acid group (―COOH) at one end and a methyl group -CH3 at the other.

    What are the three main types of fatty acids?

    The three main types of fatty acids are saturated, mono-unsaturated, and poly-unsaturated.

    What are fatty acids used for?

    Fatty acids are used for the formation of lipids. They are building blocks of lipids, which are essential biological macromolecules. 

    What are examples of fatty acids?

    Palmitic acid (saturated), alpha-linolenic acid or ALA (omega-3) and linoleic acid or  LA (omega-6).

    What are essential fatty acids?

    Essential fatty acids are polyunsaturated fatty acids vital for our health, especially the heart and the brain, but they cannot be synthesised (made) by our body. Therefore, we need to consume food high in essential fats: fish and other seafood, hemp and pumpkin seeds, leafy vegetables, etc. In humans, there are two: alpha-linolenic acid or ALA and linoleic acid or LA. ALA is an omega-3, while LA is an omega-6 fatty acid. Two other omega-3 acids of great importance for our bodies are: eicosapentaenoic (EPA) and docosahexaenoic (DHA). 

    Discover learning materials with the free StudySmarter app

    Sign up for free
    1
    About StudySmarter

    StudySmarter is a globally recognized educational technology company, offering a holistic learning platform designed for students of all ages and educational levels. Our platform provides learning support for a wide range of subjects, including STEM, Social Sciences, and Languages and also helps students to successfully master various tests and exams worldwide, such as GCSE, A Level, SAT, ACT, Abitur, and more. We offer an extensive library of learning materials, including interactive flashcards, comprehensive textbook solutions, and detailed explanations. The cutting-edge technology and tools we provide help students create their own learning materials. StudySmarter’s content is not only expert-verified but also regularly updated to ensure accuracy and relevance.

    Learn more
    StudySmarter Editorial Team

    Team Biology Teachers

    • 6 minutes reading time
    • Checked by StudySmarter Editorial Team
    Save Explanation Save Explanation

    Study anywhere. Anytime.Across all devices.

    Sign-up for free

    Sign up to highlight and take notes. It’s 100% free.

    Join over 22 million students in learning with our StudySmarter App

    The first learning app that truly has everything you need to ace your exams in one place

    • Flashcards & Quizzes
    • AI Study Assistant
    • Study Planner
    • Mock-Exams
    • Smart Note-Taking
    Join over 22 million students in learning with our StudySmarter App
    Sign up with Email

    Get unlimited access with a free StudySmarter account.

    • Instant access to millions of learning materials.
    • Flashcards, notes, mock-exams, AI tools and more.
    • Everything you need to ace your exams.
    Second Popup Banner