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Cell Division - Mitosis

Cell Division - Mitosis. So WHY do cells divide?. Smaller cells have a larger surface area (cell membrane) to volume (cytoplasm/organelles) ratio and therefore are more efficient in getting things in (nutrients) and out (wastes) of cells. When do cells divide by mitosis? a) during growth

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Cell Division - Mitosis

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  1. Cell Division - Mitosis

  2. So WHY do cells divide? Smaller cells have a larger surface area (cell membrane) to volume (cytoplasm/organelles) ratio and therefore are more efficient in getting things in (nutrients) and out (wastes) of cells.

  3. When do cells divide by mitosis? a) during growth b) for repair (regeneration) c) reproduction in single cell organisms

  4. During Growth

  5. For Repair (Regeneration)

  6. Reproduction- for single celled organisms

  7. MITOSIS Cell division in body/somatic cells

  8. One chromosome after duplication/replication has 2 chromatids! Sister chromatids made during S phase of Interphase It goes from B to C during Anaphase

  9. Some vocab • Chromosomes- long thread of DNA in nucleus - there are 46 chromosomes in each cell • Genes - small section of chromosome/DNA • Chromatids- each duplicated strand of chromosome. • Centromere- structure that holds the identical pairs of chromosomes (chromatids) together.

  10. Cell Cycle • Cell cycle includes interphase & mitosis • Interphase is the longest part of the cell cycle. • Interphase • G1 = first growth phase ~ 9 hrs • S = Synthesis phase ~ 10 hrs • G2 = second growth phase ~ 2 hrs

  11. Cell cycle memory aid • Intelligent People Meet At Three o’Clock • Intergalactic People Make A lot of Tiny Cars • Ian parties Mainly At Twelve o’Clock • Insane People Make A Terrific Casserole • Indecisive People Make A Terrifying Child • Interesting Peas Make (P)Terodactyl Clocks • Insects Poop Mega And Tough Cookies • Intelligent Prophets Make Amazing Turkey Casseroles • Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis

  12. Interphase • Parent Cell – “Resting Phase” • Cell is undergoing normal cell activities (Protein Synthesis, etc..) • Not really ‘at rest’, but not actively dividing! • The Chromosomes are in an extended form and seen as chromatin (DNA+protein) - dense mass. • The nucleus is visible. • Cell size increases • DNA of the chromosome is replicated.

  13. Prophase • Chromatin condense so that they are seen to consist of 2 chromatids joined by a centromere. • The centrioles move toward opposite poles of the cell. • Spindle fibers are produced & extend from each centrosomes. • Nuclear membrane starts to disappear • Nucleolus is no longer visible

  14. Metaphase • The chromosomes line up at the equatorial plate. • The spindle fibers from each centrioles are attached to the centromeres of the chromosomes. • The nuclear membrane has completely disappeared.

  15. Anaphase • The centromeres splits & the sister chromatids separate as each is pulled to an opposite pole. • Single strand chromatid are now called chromosomes

  16. Telophase • The chromosomes become longer, thinner, & less distinct • New nuclear membrane forms • The nucleolus reappears • Cytokinesis begins

  17. Cytokinesis • Cytoplasm divides • Cleavage furrow- cytokinesis in animal cells • Cell plate forms- cytokinesis in plant cells • Two daughter cells are formed with their own nucleus

  18. CELL IN INTERPHASE…. Daughter Cells – “Resting Phase” See the chromatin

  19. IN SUMMARY -Mitosis is: Nuclear Duplication -Cytokinesis Is Cytoplasmic division

  20. Mitosis & Chromosome Terms (ploidy = number) • Monoploid or haploid(n)- half the normal condition in animals (ie. Sex cells) • Diploid(2n)- normal chromosome condition • Tetraploid(4n)- 2times normal condition Humans: n=23 chromosome therefore… 46 chromosome in our body cells & 23 chromosomes in our sex cells If 23 = n; then 46 = 2n; and 92 = 4n

  21. Chromosome Chromosome Chromosome Interphase: The DNA Replicates & chromosomes are doubled Anaphase: the centromere splits and the 2 chromatids are now 2 chromosomes Chromatid

  22. Chromosome Condition: Interphase: 2n Prophase: 2n Metaphase: 2n Anaphase: 4n Telophase: 4n

  23. Whitefish Blastula LAB B-1-3 Drawings: METAPHASE INTERPHASE PROPHASE ANAPHASE METAPHASE ANAPHASE DAUGHTER CELLS TELOPHASE TELOPHASE

  24. http://www.iknow.net/CDROMs/cell_cdrom/cellmovies.shtml http://www.sci.sdsu.edu/multimedia/mitosis/mitosis_control.html http://www.cellsalive.com/mitosis.htm Mitosis Tutorial for Students http://www.biology.arizona.edu/Cell_bio/tutorials/cell_cycle/cells3.html http://hrsbstaff.ednet.ns.ca/bfougere/science9assist.htm

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