BIOL 320

1. BIOL 320 chp2set.ppt

2. CHROMATIN: EUCHROMATIN & HETEROCHROMATIN

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

4. TELOMERE p ARM CENTROMERE q ARM TELOMERE

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

6. 2n 2n 2n n 2n 2n 2n n 2n 2n 2n 2n Meiosis 2n Mitosis

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

8. unduplicated chromosome duplicated chromosome S Phase Mitosis S Phase Meiosis I Meiosis II daughter cells (somatic) parental cell (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. unduplicated chromosome duplicated chromosome S Phase Mitosis S Phase Meiosis I Meiosis II daughter cells (somatic) parental cell (somatic) parental cell (gonadal): “gonium” daughter cells (gonadal): “gametes”

12. CELL CYCLE and MEIOSIS

13. CELL CYCLE and MEIOSIS LEPTONEMA LEPTOTENE ZYGONEMA ZYGOTENE PACHYNEMA PACHYTENE DIPLONEMA DIPLOTENE DIAKINESIS DIAKINESIS