1. Chromosomal basis of inheritance cell division – mitosis and meiosis

2. double helix nucleosomes chromosome (metaphase) ‘supercoil’ DNA is normally dispersed in cell; condensed prior to cell division

3. Location of DNA in cells:

4. Chromosomes structure: two chromatids connected at the centromere

5. each species has a characteristic set of chromosomes individual chromosomes vary in size and shape number and size is unrelated to complexity of organism karyotype Chromosomes

6. Mitosis – cell replication interphase prophase metaphase anaphase telophase

7. Mitosis – cell replication interphase: DNA replication occurs to produce double-chromatid chromosomes prophase: DNA condenses metaphase: chromosomes align in center of cell anaphase: chromatids separate, move toward opposite poles telophase: nuclear membranes reform; cell splits into two (cytokinesis)

8. Meiosis – cell division with chromosome # reduction reductional division equational division interphase prophase I metaphase I anaphase I metaphase II anaphase II telophase II

9. crossing-over Meiosis – cell division with chromosome # reduction

10. Segregation of chromosomes Meiosis I Meiosis II

11. Oogenesis vs. spermatogenesis sperm – many, with small cellular investment mitochondria rarely transferred to zygote ova – few, with large cellular investment many mitochondria inherited

12. Oogenesis vs. spermatogenesis sperm – many, with small cellular investment mitochondria rarely transferred to zygote ova – few, with large cellular investment many mitochondria inherited (remember mitochondrial DNA?)

13. polar bodies (3)

14. each species has a characteristic set of chromosomes N = number of unique chromosomes (haploid number) 2N = number of chromosomes in somatic cells of diploid species number and size of chromosomes is unrelated to complexity of organism (e.g., nematode N varies from 1 to 48) Chromosomes