BIOL 234 - One gene three alleles worksheet(1)

BIOL 234 - One gene three alleles worksheet(1) - BIOL 234...

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

View Full Document Right Arrow Icon
BIOL 234 Summer 2017 Genetic analysis with one gene, three alleles (Yes, you are responsible for knowing this, and yes, this could be on an exam) Good news: with diploid organisms, and independent assortment (genes of interest on separate chromosomes), there are only so many possible F1/F2 ratios that we can observe. Individuals are still either homozygous or heterozygous, and alleles are still dominant/co-dominant/recessive (it depends): there are just more alleles to choose from. Activity 1 – blood types Consider the example of blood type, with which you are probably familiar. The ABO blood groups are determined by the presence or absence of sugar molecules on the surface of red blood cells. These sugars are called antigens, which means that they are recognized by cells of the immune system. There are 3 possible alleles: I A (antigen type A) I B (antigen type B) i (no antigen produced – type O) Write out all of the possible genotypes that could result in each blood type (A, B, AB, and O). What are the dominance relationships between the alleles? Now try some crosses. In cases where you can’t tell whether an individual is true-breeding, leave one allele blank at first. Then, fill in the blank with possible options for the second allele. Predict F1 phenotypic ratios for each cross, including multiple possible outcomes in cases where you don’t know if an individual is true-breeding. Cross 1: type AB x type O Cross 2: type B x type A Cross 3: type O x type A Cross 4: type AB x type B
Image of page 1

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

View Full Document Right Arrow Icon
Activity 2 – design your own problem Try this activity – it will help you to understand why you see certain ratios in the F1/F2, given certain parents. 1. Consider how many genes are involved, and how many alleles of each gene (e.g. 2 genes, one with 2 alleles, and the other with 3 alleles).
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