1. BIOL 320 chp2set.ppt

2. CHROMATIN: EUCHROMATINHETEROCHROMATIN EUCHROMATIN & HETEROCHROMATIN

3. unduplicated chromosome duplicated chromosome NUCLEUS PREPARING TO DIVIDE CHROMOSOME DUPLICATION DNA REPLICATION S PHASE OF CELL CYCLE NUCLEUS DURING DIVISION RESTING (NONDIVIDING) CELL QUIESCENCE INTERPHASE DECONDENSATION CONDENSATION CHROMOSOMEAPPEARANCE

4. CENTROMERE TELOMERE q ARM p ARM

5. unduplicated chromosome duplicated chromosome Homologous pair of duplicated chromosomes Sister chromatids sister chromatids Sister chromatids non-sister chromatids Homologues

6. 2n n n Mitosis Meiosis

7. unduplicated chromosome duplicated chromosome DNA Replication in anticipation of cell division

8. MitosisS Phase Meiosis IMeiosis II unduplicated chromosomeduplicated chromosome parental cell (somatic) daughter cells (somatic) parental cell (gonadal): “gonium” daughter cells (gonadal): “gametes”

9. Chromatin condensation Initial pairing of homologues Chromomeres appear Homology search begins Chromosomes shorten & thicken initial alignment, 300 nm Lateral elements appear Synaptonemal complex begins “bivalents,” duplicated but not apparent # bivalents = n Chromosomes shorten & thicken Synaptonemal complex developed b/w bivalents “synapsis,” 100 nm Bivalents resolve to “tetrads” Crossing over begins Crossing over apparent Sister chromatids separate Nonsister chromatids exchange “chiasmata” “Terminalization” begins Nonsister chromatids loosely attached Terminalization complete Nucleolus & nuclear envelope break down Centromeres are equatorial

10. Emerging Molecular Biology of Chromosome Junctioning and Nondisjunction

11. MitosisS Phase Meiosis IMeiosis II unduplicated chromosomeduplicated chromosome parental cell (somatic) daughter cells (somatic) parental cell (gonadal): “gonium” daughter cells (gonadal): “gametes”

12. CELL CYCLE and MEIOSIS

13. LEPTONEMA LEPTOTENE ZYGONEMA ZYGOTENE PACHYNEMA PACHYTENE DIPLONEMA DIPLOTENE DIAKINESIS