1. Mitosis

2. What is Mitosis? Division of the nucleus plus division of the cell itself (cytokinesis)Division of the nucleus plus division of the cell itself (cytokinesis) Produces two identical daughter cells during prophase, metaphase, anaphase, and telophase.Produces two identical daughter cells during prophase, metaphase, anaphase, and telophase.

3. Stages of the cell cycle An ordered set of events, culminating in cell growth and division into two daughter cells.An ordered set of events, culminating in cell growth and division into two daughter cells. Non-dividing cells not considered to be in the cell cycle.Non-dividing cells not considered to be in the cell cycle.

4. Stages of the cell cycle INTERPHASEINTERPHASE – G1 stage = "GAP 1” cell growth – S stage = "Synthesis” DNA replicationDNA replication – G2 stage = "GAP 2” organelle production MITOSISMITOSIS – M phase = nucleus divides CYTOKINESISCYTOKINESIS – cytoplasm divides  daughter cells

6. Regulation of the Cell Cycle Very complexVery complex Errors can lead to cancer.Errors can lead to cancer. –In cancer, regulation of the cell cycle goes awry –Normal cell growth & behavior is lost.

7. Ploidy Number of sets of chromosomes in a cellNumber of sets of chromosomes in a cell Haploid (n)-- one set chromosomesHaploid (n)-- one set chromosomes Diploid (2n)-- two sets chromosomesDiploid (2n)-- two sets chromosomes Most plant and animal adults are diploid (2n)Most plant and animal adults are diploid (2n) Eggs and sperm are haploid (n)Eggs and sperm are haploid (n)

8. Chromosome Characteristics Diploid set for humans; 2n = 46Diploid set for humans; 2n = 46 Autosomes = body chromosomesAutosomes = body chromosomes Female-sex chromosomes = homologous (XX)Female-sex chromosomes = homologous (XX) Male-sex chromosomes = non-homologous (XY)Male-sex chromosomes = non-homologous (XY)

9. Interphase The cell is metabolizing, growing and preparing for mitosisThe cell is metabolizing, growing and preparing for mitosis

10. Interphase Chromosomes are not clearly seenChromosomes are not clearly seen Nucleolus may be visibleNucleolus may be visible In animal cells ONLY, a pair of centrioles may start moving into position.In animal cells ONLY, a pair of centrioles may start moving into position.

11. Prophase Chromatin begins to condense and becomes visible.Chromatin begins to condense and becomes visible. Nucleolus disappears.Nucleolus disappears. Centrioles begin moving to opposite ends of the cellCentrioles begin moving to opposite ends of the cell

12. Prophase (con’t) Nuclear membrane dissolvesNuclear membrane dissolves Microtubules attach and chromosomes begin moving.Microtubules attach and chromosomes begin moving.

13. Metaphase Spindle fibers align the chromosomes along metaphase plate.Spindle fibers align the chromosomes along metaphase plate. Helps to ensure each new nucleus will receive one copy of each chromosome.Helps to ensure each new nucleus will receive one copy of each chromosome.

14. Anaphase Paired chromosomes separate and move to opposite sidesPaired chromosomes separate and move to opposite sides

15. Telophase Chromatids arrive at opposite polesChromatids arrive at opposite poles Membranes re-form around daughter nuclei.Membranes re-form around daughter nuclei. Chromosomes & spindles disperse and are no longer visible.Chromosomes & spindles disperse and are no longer visible. Cytokinesis may beginCytokinesis may begin

16. Cytokinesis: Animals Fiber ring of protein called actin around center of cell contractsFiber ring of protein called actin around center of cell contracts Pinches cell into two daughter cellsPinches cell into two daughter cells

17. Plants In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.

18. Asexual Reproduction Uses only mitosisUses only mitosis Cells duplicate to form 2 exact copies (clones) of each otherCells duplicate to form 2 exact copies (clones) of each other Most primitive form of reproductionMost primitive form of reproduction –NO GENETIC VARIATION Used by higher organisms when conditions are not favorable for sexual reproductionUsed by higher organisms when conditions are not favorable for sexual reproduction

19. Types of Asexual Reprod. Binary fissionBinary fission BuddingBudding FragmentationFragmentation RegenerationRegeneration Spore formationSpore formation ParthenogenesisParthenogenesis