29 - Recessive lethals(two copies of mutant allele are...

Info icon This preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Recessive lethals (two copies of mutant allele are lethal) YY = lethal (usually embryonic lethal) Yy = can survive (no lethality) *Note that mutant allele can be dominant Dominant lethals (one copy of mutant allele is lethal) YY = lethal (usually embryonic lethal) Yy = can survive for awhile, but eventually lethal *very rare in a population
Image of page 1

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

View Full Document Right Arrow Icon
The forward genetic approach to identifying a mutation and revealing gene interactions Step 1: Create many single-gene purebred homozygous mutant lines (with identical or similar phenotypes) and the appropriate wild type line. Step 2: Test for dominance. Step 3: Test the mutants for allelism - are they at one or several loci? Step 4: Combine the mutants in pairs to form double mutants to see if the genes interact. NOTE: To establish the chromosomal location of the gene and linkage characteristics, you would do two-factor and three-factor crosses, combined with physical mapping techniques.
Image of page 2
Phenotypic ratios in progeny reveal the type of cross
Image of page 3

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

View Full Document Right Arrow Icon
What can you conclude from a 9:3:3:1 phenotypic ratio in a dihybrid cross? two genes are involved the genes are on different chromosomes two alleles for each gene, one is dominant the other one recessive the genes act independently all alleles are completely penetrant
Image of page 4
o + / _ ; b + / _ camouflaged o + / _ ; b / b orange o / o ; b / b albino (hemoglobin of blood is visible) o / o ; b + / _ black Corn snakes have independently synthesized and inherited pigments How many genes are determining these two colors? Are they linked? Are they interacting with each other? What is the predicted F 2 phenotypic ratio if you crossed two dihybrids together?
Image of page 5

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

View Full Document Right Arrow Icon
What is the difference? linkage with recombination independent assortment Independent assortment and linkage (with recombination) results in the same number of gametes with the same genotypes. (4 different gametes) (4 different gametes) What was the meiocyte genotypes from which these gametes were derived?
Image of page 6
linkage with recombination independent assortment All four gametes occur with the same frequency .
Image of page 7

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

View Full Document Right Arrow Icon
Image of page 8
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