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Genetic Linkage

Genetic Linkage. Genetic patterns can be altered when genes are: On sex chromosomes On the same chromosome. Sex-Linkage. Genes are on the X chromosome. Sex Linkage.

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Genetic Linkage

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  1. Genetic Linkage Genetic patterns can be altered when genes are: On sex chromosomes On the same chromosome

  2. Sex-Linkage • Genes are on the X chromosome

  3. Sex Linkage • A white-eyed male Drosophila and a red eyed female produce equal numbers of offspring of each eye color. Can you rule out sex linkage with this data? Why or why not? • A red eyed male whose father had white eyes mates with a white eyed female. All of the daughters (56) have red eyes and all of the son’s (47) have white eyes. • Use a chi square analysis to reject the hypothesis that eye color is located on an autosome.

  4. Linkage • Genes that are on the same chromsome are linked. Because of crossing over ratios differ from independent assortment.

  5. How are these patterns different than expected?

  6. For the previous cross… • Use a Punnett Square to determine the expected results from a test cross. • Use a chi square to determine if the data corresponds with the null hypothesis that the genes assort independently.

  7. Linkage maps can determine location of genes on a chromosome • Crossover frequencies: • b-cn = 9% • b-vg = 17% • cn-vg = 9.5%

  8. Linkage Map

  9. Another linkage map: • Crossover frequencies: • bz-c = 4.6 cM • c-sh = 3.0 cM • What is a possible way to map these genes? • What additional information would help confirm your map?

  10. Inheritance Patterns Quiz • Most genetic disorders show this inheritance pattern.

  11. Quiz • This inheritance pattern would alter the phenotypic ratio of the offspring and in some cases you might not see individuals with the recessive trait.

  12. Quiz • The term used to describe the fact that skin color is based on the cumulative effects of 3 different genes.

  13. Quiz • Carriers, heterozygous and this term all refer to genotypes such as Bb!

  14. Quiz • Some diseases are not caused by DNA mutations but are caused by chromosomal mutations which can be observed through a karyotype. Name an example of one of these diseases.

  15. Quiz • In blood types, if an individual carries the allele for type A and the allele for type B both markers are present on their blood cells. This is an example of.

  16. Quiz • The production of melanin can be influenced by the environment which a person lives in. If a person lives at the North Pole, they will produce less melanin than an individual with the same genotype who lives at the equator. This trait is considered.

  17. Quiz • Most albino’s have inherited a hair color. Often, however, they have the phenotype of white hair. Usually pigment product is a pathway, and one of the transcription factors that controls that pathway is causing the albinism. This type of inheritance is considered.

  18. Quiz • Cystic fibrosis is a recessive disorder that affects many body systems including the respiratory system and the digestive system. It is a single gene mutation, and it is considered…

  19. Quiz.. • Hemophelia occurs more often in males. This disease is inherited…

  20. Quiz • An individual heterozygous for two traits is test crossed. The offspring that look like either of the parental phenotypes are 200 and the offspring that are recombinants are 50. This data suggests that the genes are…

  21. Mutations • Types of mutations are: • Point • Silent • Missense • Nonsense • Insertions/Deletions without frameshift • Insertions/Deletions with frameshift Mutate the DNA sequence below with each of the above. Then explain how each might affect the protein function. TAC CCA GAC CCC TTT AAA AUC

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