Sponsored Links

Poll: In this diagram of the process of DNA replication at a replication fork, the strand labeled B is the

Be advised that this is a public poll: other users can see the choice(s) you selected.

Results 1 to 2 of 2
  1. #1
    Anonymous is offline Unregistered Guest
    Join Date
    Jan 2003
    Posts
    10,092
    Downloads
    0
    Uploads
    0
    Thanks
    0
    Thanked 0 Times in 0 Posts

    The replication fork

    Advertisements



    The replication fork


    In this diagram of the process of DNA replication at a replication fork, the strand labeled B is the:






    DNA Replication

    • The two antiparallel strands are replicated simultaneously in both directions.

      RNA primers are used to initiate a new strand.

      The parent strand at the 3' end of the template determines the daughter or leading strand in continuous replication.

      The parent strand at the 5' end of the template produces the lagging strand as short pieces of DNA (100-200 nucleotides in eukaryotes and longer in prokaryotes).

      The lagging strand fragments are called Okazaki fragments after their discoverer, Reiji Okazaki.

      The RNA primers are removed by DNA polymerase and the fragments are joined by DNA ligase.



    Direction of replication




    New strands are always synthesized in the 5' to 3' direction. The 5' triphosphate can only be added to a free 3'OH of deoxyribose


    The replication fork










    ans:

    1. C leading strand


    The leading strand is the newly synthesized DNA with addition of nucleotides moving in the same direction as the replication fork. Since DNA replication is 5' to 3', this means that the leading strand will always have its 3' end towards the replication fork.





    Other problems:



    2. In this diagram of the process of DNA replication at a replication fork, the newly synthesized DNA strand labeled C is the:

    In this diagram of the process of DNA replication at a replication fork, the newly synthesized DNA strand labeled C is the:

    A coding strand

    B parental DNA

    C leading strand

    D lagging strand




    • ans: D lagging strand


      The lagging strand is the newly synthesized DNA where addition of nucleotides is on the end opposite or away from the replication fork. This fragment has its 5' end near the replication fork, and must be synthesized as short Okazaki fragments to fill in the spaces created by unwinding the DNA.


    3. In this diagram of the process of DNA replication at a replication fork, the black boxes labeled D and E are:

    A RNA primers
    B DNA template strands

    C Okazaki fragments

    D DNA polymerase

    E Newly synthesized DNA strand


    • ans:
      A RNA primers
      The initiation of replication always starts with a short RNA piece. The DNA replicating enzymes will only add nucleotides to the 3' end of DNA or RNA, and thus an RNA primase must start replication. The DNA polymerases must correct errors or "proof read", a function that is not compatible with initiation.

  2. #2
    adam is offline Junior Member
    Join Date
    Nov 2003
    Posts
    20
    Downloads
    0
    Uploads
    0
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Adam

    Great step 1. well done! thanks

Similar Threads

  1. tuning fork
    By tiggr06 in forum American University of Antigua (AUA)
    Replies: 1
    Last Post: 07-08-2011, 06:23 PM
  2. Stick a Fork In It.....It's Done
    By BabaOriley in forum The Relaxing Lounge
    Replies: 3
    Last Post: 04-09-2011, 02:15 PM
  3. viral replication
    By Asclepius1 in forum Microbiology And Immunology
    Replies: 0
    Last Post: 01-26-2005, 05:29 PM
  4. virus replication
    By FreeSpirit in forum Microbiology And Immunology
    Replies: 2
    Last Post: 12-19-2004, 11:48 PM
  5. Qn 2: Consider the process of DNA replication
    By Anonymous in forum USMLE Step 1 Forum
    Replies: 0
    Last Post: 06-03-2004, 08:28 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Site Meter