5.1: The Cell Cycle

1. 5.1: The Cell Cycle • Mitosis: cell division that results in duplicate copy of an original cell containing the exact amount of genetic information. • Happens in all somatic cells • A cell’s total inherited amount of DNA is called its genome.

2. The Cell Cycle • Interphase  Mitosis  Cytokinesis • Interphase: the growth phase in which cells make new molecules to increase its volume and mass • Further subdivided into the G1, S, and G2 phases • G1 phase: Gap 1  Rapid growth and metabolic activity • S phase: Synthesis phase  DNA synthesis and replication • G2 phase: Gap 2  Centrioles replicate, cell prepares for cell division

3. Mitosis • Division of the cell’s nucleus where the daughter cells receive the exact number of chromosomes and genetic makeup as the parent cell • Consists of the four phases: prophase, metaphase, anaphase, telophase

4. Stages of Mitosis • (Interphase) • Prophase • Metaphase • Anaphase • Telophase These 5 stages can also be subdivided into early and late stages. ex: Early telophase, late telophase

6. http://www.cellsalive.com/cell_cycle.htm

7. Interphase • During this time, the nucleus is NOT actively dividing • The growth phase in which cells make new molecules to increase its volume and mass • Chromosomes are spread out in a delicate network called chromatin • Replication of chromosomes and centrioles

8. Prophase • Centrioles move to opposite sides of the nucleus • Chromosomes start to shorten and thicken • Nuclear membrane begins to breakdown • Spindle fibres form (pathway for chromatids)

9. Metaphase • Paired chromatids line up at the EQUATOR of the cell • The centromere of each chromosome attaches to its respective spindle fibre • Nuclear membrane no longer apparent

10. Early Anaphase • Spindle fibres contract (shorten) • Centromere splits between chromatids Mid Anaphase • Chromatids separate and move to opposite poles (centrioles) Late Anaphase • Chromatids arrive at opposite sides of cell

11. Early Telophase • Nuclear membrane reappears • Chromosomes look less thick and appear as thin threads of chromatin again • Spindle fibres disappear • Nuclear division complete: daughter cell Late Telophase • Cytokinesis occurs and cytoplasm divides • Cell membrane pinches the 2 cells apart at theequator

12. http://www.sumanasinc.com/webcontent/animations/content/mitosis.htmlhttp://www.sumanasinc.com/webcontent/animations/content/mitosis.html

13. Cytokinesis • Cell division • The separation of the cytoplasm by a new cell membrane or cell wall to form two new daughter cells http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120073/bio14.swf::Mitosis and Cytokinesis Cdck- cell division activity

14. Mitosis Animation

15. Errors in Mitosis • Mutations • Cause a permanent error, or change, in the normal DNA molecules • Can be caused by various mutagens such as toxic compounds, radiation, or viruses • Mutations are passed on during anaphase and therefore are found in a localized group of cells

16. FHIT • Found on chromosome 3 • Mutation causes the FHIT gene to undergo mitosis much more rapidly causing the formation of a tumour • Oncogenes • Genes that can be activated by a mutation • Retinoblastoma, Wilms tumour, breast cancer http://nobelprize.org/educational_games/medicine/2001/cellcycle.html