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Mitosis: Cell Division

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Presentation on theme: "Mitosis: Cell Division"— Presentation transcript:

1 Mitosis: Cell Division

2 Why do cells divide? Growth Repair Replace dead cells

3 What cells divide often?
Skin Stomach lining Red Blood cells Embryo Plant roots Hair Nails

4 What cells rarely/never divide?
Nervous System Liver

5 Why do we age? Eventually cells stop being replaced “Apoptosis”
Cell death “We die because out cells die.” William R. Clark

6 “C” Terms Chromosomes Chromatid Long threads of genetic material
Found in nucleus Chromatid One side of a duplicated chromosome

7 “C” Terms Centromere NOTE
Structures that hold sister chromatids together NOTE 2 sister chromatids = 1 duplicated chromosome

8 “C” Terms Chromatin DNA tnagled around a histone (a protein)
Condensed chromatin = chromosome

9 Huh? C. Duplicated chromosome A. DNA B Chromatin histone

10 “C” Terms Centrioles Small protein bodies In cytoplasm
Animal cells only

11 Cell Division in a Nutshell
Before: Chromosome duplicates = 2 sister chromatids During: Sister chromatids separate After: 2 “daughter” cells Genetically identical

12 Cell Cycle Mitotic phase 10% Interphase 90%

13 Interphase Made up of three phases: What happens? G1, S, G2
Things necessary to divide

14 Interphase G1 Phase S Phase G2 Phase More Cell Growth
8-10 hours S Phase DNA replication Chromosome replication 6-8 hours G2 Phase More Cell Growth Centriole replication 4-6 hours

15 Mitotic Phase Mitosis Cytokinesis Division of nucleus (chromosomes)
Occurs after interphase Cytokinesis Division of cytoplasm Creates 2 daughter cells Occurs at the end of mitosis

16 Mitosis Phases IPPMAT Interphase Prophase Prometaphase Metaphase
Anaphase Telophase IPPMAT

17 Task IPPMAT Draw a diagram of mitosis
Label 6 phases & give each a short description IPPMAT

18 Interphase “Resting Phase” Precedes mitosis Prepares cell for division
Cell NOT dividing Precedes mitosis Prepares cell for division How?

19 Early Prophase Centrioles: Chromosomes now visible Make spindle fibres
Move towards opposite plates Chromosomes now visible

20 Late Prophase Centrioles reach poles
Nuclear membrane (envelope) & nucleolus start to disappear

21 Metaphase Spindle fibres attach to centromeres
Duplicate chromosomes line up at equator Guided by spindle fibers

22 Anaphase Spindle fibers retract Pull sister chromatids apart
Towards opposite polls

23 Telophase Chromatin reappears Nuclear membrane & nucleolus reappear
Cytokinesis occurs Result Two daughter cells

24 What phases do you see? B A C D

25 Cytokinesis Why would it occur differently in animal and plant cells?
Plant cells have a rigid cell wall!

26 Cytokinesis Animal Cells Cell membrane pinches inward
Creates cleavagefurrow Think: Pull a string around a balloon Plant Cells Cell Plate forms between two new nuclei Becomes cell wall

27 Cytokinesis

28 Cytokinesis

29 Plant vs. Animal – Another Difference?
Centrioles not present in plant cells What makes spindle fibers in plant cells? Form from cytoskeleton



32 Concept Map

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