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The Continuity of Life

Dive into the world of chromosomes and mitosis, exploring the cell cycle, stages of mitosis, and the significance of DNA replication. Discover how binary fission drives reproduction in prokaryotes.

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The Continuity of Life

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  1. The Continuity of Life Mrs Tagore

  2. Key words: • Histone proteins • Centromere • Karyotype • Homologous • Autosome • Heterosome • Sex chromosomes • Haploid • Diploid • Somatic cell • Locus/loci • Alleles • Homologous chromosomes • Plasmid • nucleoid

  3. Chromosomes and Eukaryotes Read pages 15-16

  4. Chromosomes and Eukaryotes Read pages 15-16

  5. Chromosomes and Eukaryotes Read pages 17-18

  6. Chromosomes of Prokaryotes Read pages 18-19

  7. Questions • Complete questions 1-10 for tomorrow. • We will be discussing these in class, so I’ll be checking that you have done it!!

  8. Title: Mitosis Learning question: What are the names of the stages of mitosis? Hook: What connects these pictures? (Can you write more than one word?!)

  9. Lesson Aims • Describe the cell cycle • Understand that mitosis is only one small part of the overall cell cycle • State the events that occur at each phase of the cell cycle • Describe each stage of mitosis • Identify each stage of mitosis from diagrams and micrographs

  10. Key words… • Mitosis • Prophase • Metaphase • Anaphase • Telophase • Microtubules • Cytokinesis • Chromatid • Chromasome • Centromere • Centriole • Diploid

  11. Cell division • All complex organisms originated from a single fertilised egg. • Every cell in your body started here, through cell division the numbers are increased. • Cells then specialise and change into their various roles

  12. Mitosis • Mitosis is the process by which new body cell are produced for: • Growth • Replacing damaged or old cells. This is a complex process requiring is to be split into different stages to understand it.

  13. DNA • ‘Blueprint of life’ • Codes for all the proteins needed for life • Describes that characteristics of every living thing • Every cell with a nucleus contains ALL the instructions to make the organism • http://www.pbs.org/wgbh/nova/photo51/media/journey.swf

  14. Chromosomes • Each DNA strand is split into chromosomes • All sexually reproducing animals have pairs of chromosomes. One set of each pair comes from each parent • Humans have 23 pairs • Lions have 19 pairs • African wild dogs have 39 pairs • Mosquito have 3 pairs • Some ferns have 500-600 pairs

  15. This (imaginary, example) animal has just two pairs of chromosomesRed = Maternal Blue = Paternal 1p 1m 2p 2m

  16. During Interphase, each chromosome replicates and produces an exact copy of itself: 1p + copy 1m + copy 2p + copy 2m +copy

  17. There are four stages to Mitosis • Prophase • Metaphase • Anaphase • Telophase • Remember though that this is a continuous process P M A T

  18. Interphase • Standard condition of cell • DNA replicates • Cell enters reproductive cycle with 2 copies of each chromosome

  19. Prophase • DNA super coils and chromosomes become visible • Nuclear membrane breaks down • Centrioles migrate to poles

  20. Metaphase • Chromosomes line up centromeres on equator of cell • Centrioles form spindles

  21. Anaphase • Spindles ‘grip’ centromeres and chromosomes migrate to poles

  22. Telophase • Nuclear membranes reform • Chromosomes disperse • Cytokinesis begins

  23. Interphase • Both daughter cells are exact copies of the parent cell

  24. INTERPHASE MITOSIS

  25. Stages of Mitosis • http://www.cellsalive.com/mitosis.htm

  26. In humans, each cell (except sex cells) has how many chromosomes? ______ • After mitosis, how many daughter cells are produced?  _______.  After mitosis (in a human cell), each daughter cell has how many chromosomes? _____ • How many phases are in MITOSIS? ___________ • Which phase of the cell cycle is the longest?  _________ • During which phase does cytokinesis begin?  __________ • What cell parts migrate to the poles during prophase? __________________. • What structure holds the two chromatids together? ____________________ • During which phase does the nuclear membrane dissolve? __________________ • What structure moves the chromosomes into position and then pulls them apart? ___________________ • What is the overall purpose of mitosis? _________________________

  27. Name the stages!

  28. Binary fission

  29. Binary fission • Prokaryotes reproduce by binary fission • No nucleus, centromere or chromosomes, therefore no mitosis • Two daughter cells produced • Cell replication>new DNA attaches itself to different part of cell membrane>cell pulls apart separating replicate and original DNA> wall forms dividing cells into two cells with identical genetic composition • Mitochondria and chloroplasts also use binary fission to form new organelles

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