ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Carbohydrates - Part One

Updated on October 7, 2015

What are Carbohydrates?

This hub series serves to explain what carbohydrates are and what different kinds of them there are (including examples). Primarily, this hub will be used for revising the A Level Topics concerning carbohydrates by students who wish to know everything they need to about carbohydrates for their exams.

Any molecule that falls under the molecular formula Cm(H2O)n is classified as a carbohydrate.

To remember this, realise that the very word “carbohydrate” means hydrating (adding water to) carbons. That is, adding H2O to C, or 'CH2O'.

Carbohydrates have a total of 4 categories:

  1. Monosaccharides,
  2. Disaccharides,
  3. Oligosaccharides,
  4. Polysaccharides.

However, sometimes "oligosaccharides" are placed under "polysaccharides" to make things simpler. This is true for school exams such as the AS Edexcel exam where the term "oligosaccharides" will never be used.


Molecular structure of glucose.
Molecular structure of glucose. | Source


Molecular Structure of Galactose
Molecular Structure of Galactose | Source


Monosaccharides are single units of sugar and are the monomers (subunits) of bigger molecules called polymers.

You must know that these indeed are monosaccharides and the facts about them:

  • Glucose - The main sugar used by cells in respiration. Glycogen, starch and cellulose are all polymers of glucose and are broken down into it when energy is needed within an organism.
  • Fructose - Naturally occurs in fruit, honey and various vegetables. It has a sweet scent and is therefore used as part of seed dispersal, attracting animals to eat the fruit and defecate the seeds.
  • Galactose - Combines via condensation reaction to form the disaccharide 'lactose', an abundant sugar in milk.

    Note: The only difference between glucose and galactose is that the -OH on carbon 4 faces a different way. They both have the same molecular formula: C6H12O6.

Table Sugar - "Sucrose"
Table Sugar - "Sucrose" | Source


Disaccharides are compiled of two monosaccharides and are formed out of a condensation reaction (giving off water) between them.

The disaccharides that you must know about include:

  • Sucrose - 'The Table Sugar', a disaccharide consisting of one glucose and one fructose molecule. It is the form in which sugar is transported around the plant.
  • Maltose - A disaccharide of two glucose molecules. It is produced when amylase (found in saliva) breaks down starch, and then is itself broken down into glucose. It is found in germinating seeds which break down their starch reserves in order to access glucose for much needed respiration.
  • Lactose - A disaccharide of glucose and galactose. It is found in milk.

Starch is Everywhere!
Starch is Everywhere!


Polysaccharides are made up of many monosaccharides which join together via glycosidic bonds.

The following three polysaccharides are all polymers of glucose:

  • Starch
  • Glycogen
  • Cellulose

All 3 of these are not very soluble and do not taste sweet.

Carbohydrate Structure Explained by Video


    0 of 8192 characters used
    Post Comment
    • profile image


      8 years ago

      this is very helpful!

    • Philanthropy2012 profile imageAUTHOR


      9 years ago from London

      Very glad I could help :)

    • profile image


      9 years ago

      This is great! thanks it helped me study!!


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)