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Transcript of All cells come from pre-existing cells New cells are produced for growth and to replace damaged or...
![Page 1: All cells come from pre-existing cells New cells are produced for growth and to replace damaged or old cells New cells are produced for growth and to.](https://reader038.fdocuments.us/reader038/viewer/2022103023/56649efa5503460f94c0cf34/html5/thumbnails/1.jpg)
Cell Division (Mitosis)
102 BOT
Lab 3
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• All cells come from pre-existing cells• New cells are produced for growth
and to replace damaged or old cells• It is required for growth in
multicellular organisms• It is necessary for reproduction in
unicellular or multicellular organisms
Cell division is a fundamental process
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• Life cycle requires two distinct types of cell division processes:
mitosis and meiosis• Cell division: is the process that
results in the multiplication of cells (one cell becomes two cells during an organism’s life cycle)
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Mitosis and Meiosis
• Mitosis:-division of somatic (body) cells
• Meiosis-division of gametes (sex cells)
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Mitosis Some haploid & diploid cells divide by mitosis. Each new cell receives one copy of every
chromosome that was present in the original cell.
Produces 2 new cells that are both genetically identical to the original cell.
DNA duplication during interphase
Mitosis
Diploid Cell
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Mitosis can be divided into stages
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
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InterphaseThe cell prepares for division
– DNA replicated– Organelles replicated– Chromosomes are not clearly discerned in the
nucleus– Cell increases in size
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ProphaseThe cell prepares for nuclear
division– Chromosomes thicken and shorten (become
visible)– Chromatids joined by a centromere– Nucleolus disappears– Nuclear membrane disintegrate– The mitotic spindle begins to form
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MetaphaseThe cell prepares chromosomes for
division– Chromosomes line up at the center of the cell– Spindle fibers attach from daughter cells to
chromosomes at the centromere
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AnaphaseThe chromosomes divide
– The spindle fibres begin to contract– This starts to pull the sister chromatids apart– Spindle fibres contract pulling chromatids to
the opposite poles of the cell
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TelophaseThe cytoplasm divides
– In telophase the cell actually divides.–The nuclear envelope re-forms
around the two sets of chromatids.–Nucleolus reappears
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Cytokinesis
– In plant cells, Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.
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Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
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Overview of Mitosis
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MeiosisMeiosis is the type of cell division by
which germ cells (eggs and sperm) are produced .
One parent cell produces four daughter cells .
Daughter cells have half the number of chromosomes found in the original
parent cell
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Overview of Meiosis
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Differences in Mitosis & Meiosis
• Meiosis– Sexual– Cell divides twice– Four haploid
daughter cells– Genetic
information is different
• Mitosis– Asexual– Cell divides once– Two daughter
cells– Genetic
information is identical
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Comparison of Mitosis & Meiosis
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Munirah Al-Dossari