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Homework Help: DNA family tree: who is the grandmother, mother, and daughter?

  1. Apr 22, 2007 #1
    1. The problem statement, all variables and given/known data
    By running a DNA blast, we need to identify who is the grandmother, mother, and daughter. And how/why do we know their relationship.

    The tree is attached.

    2. Relevant equations

    Here are some of the results from blast, I'm not sure if they will help:
    Group 1: Sequences: 2 Score:7298
    Group 2: Sequences: 2 Score:7245
    Group 3: Sequences: 3 Score:7127
    Group 4: Sequences: 4 Score:7118
    Group 5: Sequences: 2 Score:7448
    Group 6: Sequences: 3 Score:7448
    Group 7: Sequences: 4 Score:7354
    Group 8: Sequences: 8 Score:7075
    Group 9: Sequences: 10 Score:7108
    Group 10: Sequences: 11 Score:7029
    Group 11: Sequences: 12 Score:6977

    3. The attempt at a solution

    Just by looking at the tree, my guess will be 4 is the grandmother, 6 is the mother, and either 9 or 13 is the daughter. However, I can't justify it.
    Where should I look?

    Any help is appreciated.

    Thank you all.

    Attached Files:

    Last edited: Apr 22, 2007
  2. jcsd
  3. Apr 25, 2007 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    I don't know enough about this method to help you all the way through the problem, but one thing to keep in mind is that the distance between any two individuals in the tree indicates their relative relatedness. In other words, if the line connecting two individuals is very short, they are closely related, and if it's very long, they are very distantly related.

    As an example, 5 and 11 are very closely related, while 5 and 8 are more distantly related.
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