Understanding Chromosome Movements in Meiosis and Mitosis

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3. Introduction: Biological significance Non-disjunction- the failure of homologous chromsomes to separate Aneuplody: Down Syndrome Application to human health: problems in embryonic development Use your noodle: Understanding the role of chromosome movements in meiosis and mitosis. Chromosomal movement during mitosis results in the formation of two identical daughter cells Chromosomal movement during meiosis results in four haploid gametes with half the number of chromosomes as the diploid mother cell

4. ACTIVITY I, II, III - MEIOSIS STRIP SEQUENCE WITH CHROMOSOME DANCE Learning Goals Students will be able to explain the movement of chromosomes during mitosis, meiosis, and predict the products. Active learning includes a strip sequence that will direct a visual demonstration of chromosome movement. This will be followed by clicker questions. Diversity This activity addresses a varietyof learning styles, including auditory, visual, kinesthetic and analytical. Students will also work cooperatively.

5. ACTIVITY 4- Case study of a Down syndrome baby with with multiple abnormalities. Learning Goal Students will learn to formulate hypotheses, and design models to test their hypotheses using data from a case study. Active learning Think-pair-share groups will formulate models to explain causes of Down syndrome, and will predict karyotypes consistent with their models. Diversity This activity includes students that can learn by visual, analytical and interactive styles.

6. Students by this point will have seen a mini-lecture on the following: - chromosomes, chromosome replication, chromatids, centromeres - homologous chromosomes - diploid, haploid - gametes, zygotes - chromosome movements in mitosis - the life cycle: 2n  n  2n - spindle, poles - the salient features of meiosis

7. MEIOSIS Chromosome from father Chromosome from mother 2n Before DNA replication

8. MEIOSIS centromere centromere Sister chromatids Sister chromatids After DNA replication

9. MEIOSIS Pairing of homologous chromosomes

10. MEIOSIS n n End of meiosis I Two cells

11. MEIOSIS gametes n n n n End of meiosis II Four cells

12. Group Activity: Place the following events in the order they occur in meiosis: • 2n cell completes DNA replication • Sister chromatids separate • Homologous chromosomes separate to opposite poles and cells divide • Homologous chromosomes pair and align in the middle of the cell • Gametes contain a single set of chromosomes • Daughter cells contain a single set of chromosomes, each chromosome consists of two sister chromatids A B C D E F

13. Group Activity: Place the following events in the order they occur in meiosis: • 2n cell completes DNA replication • Homologous chromosomes pair and align in the middle of the cell • Homologous chromosomes separate to opposite poles and cells divide • Daughter cells contain a single set of chromosomes, each chromosome consists of two sister chromatids • Sister chromatids separate • Gametes contain a single set of chromosomes A D C F B E

14. Acknowledgements Group 5 Members University of California, Riverside Richard Cardullo Morris Maduro University of Alabama Katrina Ramonell Jane Rasco Stony Brook University Neta Dean Gene Katz Louisiana State University Pat DiMario Group Facilitator – Brian Manske Pool Noodle Facilitator – Sandy Gossens

16. Fusion of gametes + sperm 2n zygote egg

17. MEIOSIS - nondisjunction n n-1 n n+1

18. Fusion of gametes + sperm 2n+1 zygote egg (aneuploid)

19. Fusion of gametes + sperm 2n-1 zygote egg (aneuploid)

21. Use your noodle: Understanding the role of chromosome movements in meiosis and mitosis.

22. 1 Developmental delay -- All children with Down syndrome are delayed, although this may not be apparent until the child is beyond infancy. IQ scores range from 20 (severe mental retardation) to 85 (low normal). Overall learning abilities are usually equivalent to a 6 to 8 year old child without Down syndrome. 2 Gastrointestinal abnormalities -- 2 percent to 5 percent of children have complete obstruction of the small bowel known as duodenal atresia. Another 2 percent have poor movement abilities of the colon and / or rectum known as Hirschsprung disease. 3 Hearing loss -- Some degree of hearing loss is present in 40 percent to 75 percent of children with Down syndrome. Malformations may affect either the middle or inner ear structures. Ear infections can be a frequent, often difficult problem to treat. 4 Eye disorders -- 60 percent of children have eye disorders that need monitoring and treatment. Congenital cataracts (loss of transparency of the lens of the eye), glaucoma (increased pressure within the eye), strabismus (cross-eyed) and major refractory errors (far sighted or near sighted) are the common problems. 5 Leukemia -- Leukemia occurs in one of every 150 children with Down Syndrome. This is 20 times higher than the general population. 6 Thyroid disorders -- Low thyroid levels are seen in approximately 5 percent of children with Down syndrome.

28. Application: A karyotype is a display of condensed chromosomes arranged in pairs.

29. MITOSIS Chromosome from father Chromosome from mother 2n Before cell division and replication

30. MITOSIS alignment

31. MITOSIS centromere centromere Sister chromatids Sister chromatids After replication

32. MITOSIS segregation

33. MITOSIS 2n 2n Daughter cells