ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel
  • »
  • Education and Science»
  • Life Sciences

Discovering DNA Packaging into the Nucleosome

Updated on July 4, 2011

Discovering DNA Packaging

Dna Packaging is the folding of DNA to fiit a cell’s limited space. This process differs greatly from Prokaryotic cells to Eukaryotic cells and is much better understood in Eukaryotes. The packaging unit of DNA is called the nucleosome which is basically 8 proteins with 2 DNA strands wrapped around it 2 times. These histone proteins include: H1, H2A, H2B, H3, and H4. When Chromatin (DNA that hasn’t condensed into chromosomes) is put into a low salt solution, it takes the form of “Beads on a string”. It literally looks like those Mardi gras necklaces. When Chromatin is put into a solution with 0.15M KCL, takes the form of the “30-nm fiber” where the DNA now looks like a long thick snake.

DNA packaging has a big problem:

1. The longest human chromosome has 3 X 10^8 base pairs (adenine, cytosine, guanine, thymine). That is equivalent to 10cm. The problem is fitting that much DNA into a cell. A typical cell is 10 micrometers and therefore DNA needs to be compacted 10,000X.

How was the nucleosome (packaging unit of DNA) discovered?

The Experiment:

1. The Nuclei was isolated

2. DNAse I (an enzyme which cuts DNA at random locations by breaking phosphodiester bonds) was used to partially digest the DNA (Chop the DNA into fragments).

3. Run the DNA fragments through an agarose gel (which separates the DNA by size)

Result: Scientists found that the DNA fragments were 150- 200 base pairs long (This is weird because DNAse I cuts the DNA at RANDOM places and DNA is VERY long. Because each fragment were about the same length as the next one it means something is blocking the DNA from being randomly chopped up.

Conclusion: This means something is protecting the DNA and that is the histones: H1, H2A, H2B, H3, and H4

To be more precise, the scientists did this:

4. Put in more DNAse so the DNA could be cut up further

5. Run the DNA through Acrylamide gel instead of agarose which provides a better separation

Result: They found that the DNA Fragments are now multiples of 10 – 11 base pairs long. VERY precise.

Conclusion: DNA must be wrapped around the outside of the nucleosome. This also shows that the DNA is bDNA because it is always around 10 base pairs.

Comments

    0 of 8192 characters used
    Post Comment

    • TFScientist profile image

      Rhys Baker 6 years ago from Peterborough, UK

      Excellent description of the nucleosome experiment. There are a number of visuals available for apoptosis that show CAD cutting between the nucleosomes during fragmentation of chromatin in...you guessed it...ladders of multiples of 11. Nice Hub.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com 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: "https://hubpages.com/privacy-policy#gdpr"

    Show Details
    Necessary
    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 googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    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)
    Marketing
    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.
    Statistics
    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)