Lecture_8 - EEMB 129 LECTURE 8 2010 I Linkage(Chapter 5 X2...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
EEMB 129 - LECTURE 8 2010 1 I. Linkage (Chapter 5) X2 Test Tetrad Analysis X 2 Test When testing for linkage, how different from 50% do the recombinant classes need to be before we conclude that two genes are linked? X 2 = sum of the (Obs - Exp) 2 Exp As the Obs approaches the value of the expected, then the X 2 value is small If the Obs is fairly different than the expected, then the X 2 value will be larger AaBb x aabb Expected if independently OBS assorting O - E (O - E) 2 (O-E) 2 /E AaBb (AB) 18 12.5 5.5 30.25 2.42 Aabb (Ab) 7 12.5 -5.5 30.25 2.42 aaBb (aB) 10 12.5 -2.5 6.25 0.5 aabb (ab) 15 12.5 2.5 6.25 0.5 50 50 5.84 degrees of freedom: # of freely varying parameters. If you examine 50 individuals, any three classes can vary freely, but once you specify how many individuals are in three classes, the last class is fixed. for 3 degrees of freedom, we can then look at a X 2 table Now look at a Chi-square table: Find the row for the degrees of freedom Look across to see where your X 2 value lies Look up to the probability to see between which values your value lies X 2 , df = 3 2.37 < 5.84 < 6.25 corresponding P 0.50 p 0.10 Therefore IF the genes truly were independent (the null hypothesis), THEN you would have between 10-50% chance of obtaining a X 2 value of 5.84
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
EEMB 129 - LECTURE 8 2010 2 Tetrad Analysis: There are a number of questions about meiosis that cannot be answered by traditional genetic methods (i.e., with diploid organisms such as fruit flies).
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern