1. Mitosis and the Cell Cycle
Cell reproduction

2. Some Definitions Somatic Cells – body cells
Produced through mitosis
Has 46 chromosomes (23 pairs)
Homolog – each member of a chromosome pair
Diploid (2n) – total of 46 chromosomes in people – zygote & somatic cells
Haploid (n) – total of 23 chromosomes in people, gametes (sperm & egg)

3. The mitotic phase alternates with interphase in the cell cycle: an overview
The mitotic (M) phase of the cell cycle alternates with the much longer interphase.
The M phase includes mitosis and cytokinesis.
Interphase accounts for 90% of the cell cycle.
Fig. 12.4
Boehm 2011
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

4. Interphase Interphase has three subphases:
the G1 phase (“first gap”) centered on growth,
the S phase (“synthesis”) when the chromosomes are copied, (longest phase of cell cycle)
the G2 phase (“second gap”) where the cell completes preparations for cell division, (shortest phase of interphase)
and divides (M).

5. Mitosis
Happens in all cells
Cell division process
5 major stages

6. Prophase Nuclear envelope disappears
Chromosomes condense – can see sister chromatids
and centromere
Spindle forms

7. Metaphase Chromosomes move to the equator of spindle
Each chromatid is attached to spindle with centromere

8. Anaphase Centromeres split
Sister chromatids are pulled apart to opposite poles of the cell
Each chromatid is now a separate chromosome

9. Telophase
Nuclear envelopes (2) reform
Chromosomes begin to uncoil

10. Cytokinesis
Cytoplasm divides
Two new daughter cells are now separate

11. Fig left
Boehm 2011
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

12. Fig right
Boehm 2011
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings