1. The SDN iPhone App is back and free through November! Get it today and please post a review on the App Store!
    Dismiss Notice
  2. Dismiss Notice
  3. Guest, be sure to check out How To Get Into Dental School, our free downloadable PDF with step-by-step details for dental school applicants!
    Dismiss Notice
  4. Dismiss Notice
Dismiss Notice

Interview Feedback: Visit Interview Feedback to view and submit interview information.

Interviewing Masterclass: Free masterclass on interviewing from SDN and Medical College of Georgia

bio question

Discussion in 'DAT Discussions' started by ekl1984, Dec 2, 2008.

  1. ekl1984

    2+ Year Member

    Joined:
    Nov 19, 2008
    Messages:
    10
    Likes Received:
    0
    Status:
    Dental Student
    So I know that an egg cell and a sperm cell are each haploid (with 23 chromosomes and 23 chromatids). Then when they fuze they create a diploid zygote with 46 chromosomes. But when are the chromatids of each chromosome duplicated?
     
  2. Note: SDN Members do not see this ad.

  3. 911dds

    2+ Year Member

    Joined:
    Jul 9, 2008
    Messages:
    56
    Likes Received:
    0
    Status:
    Pre-Dental
    Once the sperm and egg meet they continue with meiosis II. Remember the egg stopped at Prophase I of meiosis. Ovulation completed Meiosis I and once the egg and sperm join it continues with Meiosis II the duplication portion. Am I correct? Anyone?
     
  4. ekl1984

    2+ Year Member

    Joined:
    Nov 19, 2008
    Messages:
    10
    Likes Received:
    0
    Status:
    Dental Student
    I think you have things confused. There is no "duplication portion" in meiosis II. When the egg and sperm fuze they have each gone through meiosis II and are haploid with 1 chromatid on each chromosome. The zygote is diploid, but i think each chromosome still had only 1 chromatid. so my question is, when do the chromosomes duplicate their chromatids?
     
  5. chessxwizard

    7+ Year Member

    Joined:
    Jul 28, 2007
    Messages:
    291
    Likes Received:
    0
    Status:
    Pre-Dental
    They duplicate their chromatids prior to mitosis that occurs after fertilization.
     

Share This Page