5 1 mitosis n.
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5.1 MITOSIS PowerPoint Presentation
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  2. THE NECESSITY FOR THE REPRODUCTION OF NEW CELLS ORGANISMS. • Mitosis is the process of cell division that produces two daughter cells which are genetically to each other and to their parent cell. • The significance of mitosis in living things: • Repair and replace the damaged or dead cells • Increases the number of unicellular organisms. • Ensures that new cell are genetically identical to the parent • Preserve the diploid number of chromosomes • Increases the number of cells in individuals(single-celled organisms) • Aids in growth process(multi-celled organisms)

  3. The phases in the cell cycle • Cell cycle-the life of a cell from the time it is produced until it completely divides into two new daughter cells. • Activity of the cell during mitotic division: • Preparing for the division • Produce cytoplasm and organelles-formation of daughter cells. • Two major phases: • Interphase • Mitotic cell division(M Phase)

  4. Phase in Cell cycle

  5. Interphase

  6. This is the resting or non-mitotic of the cell cycle It comprise G1,S and G2 stage of the cell cycle DNA is replicated during the S phase of interphase Interphase

  7. PROPHASE If the first stage of mitosis The chromosomes condense and become visible The centrioles form and move toward opposite ends of the cell(the pole) The nuclear membrane dissoves and the mitotic spindle thread is formed(from the centrioles) Spindle fibers from each centriole attach to each sister chromatid at the kinetochore Chromatids are connected at the centromere The M phase(mitosis and cytokinesis)

  8. METAPHASE The chromosomes lined up on the cell equator which is the metaphase plate The spindle fibres are formed completely

  9. ANAPHASE Spindle attached to kinetochores begin to shorten This exerts a force on the sister chromatids and pulls them apart Spindle fibres continue to shorten,pulling chromatids to opposite poles of the cell Early anaphase Late anaphase

  10. TELOPHASE Both chromosomes have reached the opposite poles The chromosomes decondensed The nuclear enveloped is formed Nucleus reformed The spindle fibres dissappear Once separate,the chromatds are again called chromosomes Two daughter nuclei are formed with identical set of chromosomes

  11. Cytokinesis is the process of the cytoplasm division after the separation of chromosomes Cytokinesis

  12. The importance controling mitosis • To ensure that organism can function properly • To ensure that organisms can grow and develop normally • To help in repairing damage cells and tissues for the survival of life

  13. The effects of uncontrolled mitosis in living things • It due to the changes of gene which control the cell cycle e,g:The growth of cancerous cell • Cancerous cells could lead to the death of the organism if it is not prevented from invanding and destroying neighbouring cells • This condition can be caused by certain virus,toxic chemical susbtances • The cells divide very fast and unregulated.(Tumour) • Benign tumour-Abnormal cells that remain at the original site and be removed by surgery • Malignant tumour-becomes invasive and spreads to neighbouring tissues and cells (cancer)

  14. The application of knowledge on mitosis in cloning • Production of genetically identical individuals Cloning of sheep

  15. Producing genetically identical organisms which carry a useful gene • A piece of DNA carrying a gene of interest and a gene for antibiotic resistance • The cells is grown on a medium containing the antibiotic so that only the cells with the inserted DNA will survive • The nuclei from surviving cells is inserted into unnucleated egg cells • The egg cells is implanted into the surrogate mother • Clone which carry the useful gene are born

  16. Application of cloning technology is important to: • Produce genetically identical organs for transplantation • Produce human tissues • Repopulate endangered species

  17. The advantages and disadvantages of cloning