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Cell division - mitosis

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Presentation on theme: "Cell division - mitosis"— Presentation transcript:

1 Cell division - mitosis

2 Cell division Cell division is needed for:
reproduction in unicellular organisms growth in multicellular organisms replacement of damaged or dying cells repair of damaged organs or tissues

3 Mitosis Involves: replication of DNA
controlled division of the nuclear material so new each cell has the same DNA or number of chromosomes division of cytoplasm and organelles so each new cell has similar contents

4 Chromosomes Chromosomes are only visible during cell division
They consist of two strands (chromatids) of tightly coiled DNA joined at the centromere They hold all the genetic information that controls the activities of cells

5 DNA replication Occurs in interphase – before mitosis starts
One set of enzymes split the strands Another set of enzymes join new nucleotides to each strand Nucleotides match up by the base pairing rule (C – G, A - T) The end result is two identical strands, joined at a point called the centromere

6 Cell cycle

7 Stages of mitosis

8 Interphase Phase of growth and normal metabolism
Nucleus and nucleolus visible DNA replication occurs just before cell division occurs

9 Prophase First stage of division Nucleus and nucleolus disappear
Spindle starts to form DNA condenses and becomes visible as chromosomes Centrioles move to opposite poles (animal cells)

10 Metaphase Chromosomes line up on spindle at the equator of the cell

11 Anaphase Chromatids pull apart at the centromere
One chromatid from each chromosome moves to each end of the cell

12 Telophase Chromosomes uncondense and a new nucleus forms around them
The cytoplasm splits (cytokinesis) to form two new cells identical to the original except smaller

13 Interphase Phase of growth and normal metabolism
Nucleus and nucleolus visible

14 Identify the stages of mitosis
telophase anaphase interphase metaphase early prophase early prophase metaphase early prophase

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