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It’s all in the Chromosomes!

It’s all in the Chromosomes!. Bringing together Meiosis, Mendelian Genetics, and Gene Linkage!. Meiosis holds to key to why we observe the things we do in the field of Genetics. Let’s revisit it to find out why!. Back to Basics- Meiosis!. ?. ?. Karyotypes. ?.

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It’s all in the Chromosomes!

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  1. It’s all in the Chromosomes! Bringing together Meiosis, Mendelian Genetics, and Gene Linkage!

  2. Meiosis holds to key to why we observe the things we do in the field of Genetics. Let’s revisit it to find out why! Back to Basics- Meiosis!

  3. ? ? Karyotypes ? What’s the difference between these two?

  4. Prophase I of Meiosis I Formation of Tetrad and Crossing Over

  5. Anaphase I of Meiosis I What does this mean? The matching chromosomes from the male and female paired up and exchanged information (Alleles!). Now they separate so that both pairs of chromosomes are no longer traveling together!

  6. The End Result of Meiosis I Why are the two daughter cells haploid?? Think about what makes something Diploid or Haploid!

  7. Both cells created in Meiosis I enter Meiosis II! This is why the result of Meiosis is FOUR daughter cells (also, haploid!)

  8. Anaphase II of Meiosis II What’s the difference? Why are the resulting daughter cells still HAPLOID after two “pullings”? Vs.

  9. The Principle of Independent Assortment States: • Alleles for one trait segregate independently of those for another trait • Ex. Alleles for seed color separate independently of those for seed shape– This is why we get combinations not found in either parent! Back to Basics- MENDEL! Here we’re crossing two heterozygous round yellow plants. The offspring have phenotypic combinations not seen in the parents! Because of Independent Assortment of Alleles!

  10. Which phase of Meiosis best explains the Law of Independent Assortment? Work independently and turn over your work when you are finished.

  11. Gene Linkage When Genes are on the Same Chromosome

  12. Thomas Hunt Morgan identified more than 50 genes in the fruit fly • Some of those genes appeared to “stick together” more than others • A fly with Red eyes would often have miniature wings – the genes for those traits were often inherited together • (GAH! How is that possible?!) Breaking the Law

  13. The Law of Independent Assortment applies to Chromosomes, not to Genes! Breaking the Law? The Chromosomes assort independently, but not necessarily the genes on them! YES YES NO

  14. Genes on the chromosome are often “Linked” together • Linked genes are often inherited together, like the fly’s red eyes and miniature wings! Gene Linkage!

  15. The closer together two genes are on a chromosome, the more likely they are to be inherited together! • If they are located farther apart on the same chromosome, they may still be separated by Crossing Over! Gene Linkage! Critical Thinking: Why is this significant?

  16. Fact: This is super exciting! • BECAUSE the closer together two genes are on a chromosome, the more likely they are to be inherited together (and the farther apart they are, the more likely they are to be segregated), we can use the frequency of trait inheritance to make a GENE MAP! • Tells us WHERE GENES ARE on the chromosome! Gene Mapping! OMG!!!! If traits A and B are always inherited together, we would know that they are located close together on the chromosome!

  17. Gene Mapping

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