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REPRODUKSI SEL

REPRODUKSI SEL. Reproduksi protista berbeda dengan sel hewan lainnya Jamur → spora Tanaman → biji Hewan → telur Protista → sel tunggal. Sel anak → mempunyai membran, sitoplasma dan inti Inti mengandung DNA yang identik. Salah satu protista adalah amoeba

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REPRODUKSI SEL

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  1. REPRODUKSI SEL

  2. Reproduksi protista berbeda dengan sel hewan lainnya Jamur → spora Tanaman → biji Hewan → telur Protista → sel tunggal Sel anak → mempunyai membran, sitoplasma dan inti Inti mengandung DNA yang identik

  3. Salah satu protista adalah amoeba Amoebas → sangat tipis, membran sel fleksibel Bergerak dengan menjulurkan sitoplasma keluar membran dan membentuk pseudopods ("false feet") Di dalam sel terdapat ruang sbg organ percernaan

  4. REPRODUKSI SEL • MITOSIS → sel somatik • MEIOSIS → sel seks atau gamet (spermatozoa dan ovum)

  5. MITOSIS Interfase Metafase Anafase Profase Telofase • Terjadi sintesis protein; kromatin dan inti nampak jelas; replikasi DNA • Kromatin tebal → kromosom; membran inti melebur; sentriol bergerak pada sisi yang berlawanan dan serabut spindel mulai terbentuk • Kromosom yang dihubungkan spindel ada di tengah • Kromosom memisah menuju ke kutub yang berlawanan • Kromosom kembali berbentuk kromatin; speindel melebur; membran inti nampak; sentriol replikasi; terbentuk membran sel baru

  6. Cell ReproductionInterphase (before Mitosis) Early Prophase Prophase Late Prophase Transition to Metaphase Metaphase Anaphase Telophase

  7. MEIOSIS : Terdiri dari 2 fase : • Meiosis I : merupakan pembelahan yang memisahkan 2 kromosom homolog (kromatid), terjadi reduksi kromosom • Meiosis II : merupakan pemisahan kromatid melalui pembelahan sentromer. Hasilnya : sel diploid menghasilkan 4 sel anakan yang haploid Tahap-tahapnya sbb :

  8. PROPHASE I • SYNAPSIS - the pairing and bonding together of homologous chromosomes to form tetrads • Homologous chromosomes consist of one maternal and one paternal chromosome

  9. PROPHASE I CROSSING-OVER: • Exchange of chromatid segments within tetrads to produce new allele combinations • Nonsisters cross over, break, and rejoin • Increases genetic variety VIEW OF NUCLEUS AND TETRADS

  10. CROSSING -OVER • Notice the exchange of segments that has happened in two places on the larger homologous pair • This is crossing over

  11. METAPHASE I • Tetrads line up in the middle of the cell in a straight line at equator • Spindle fibers attach to only 1 kinetochore of each centromere

  12. ANAPHASE I • Tetrads are separated as homologous chromosomes are pulled to opposite poles of the cell • (Remember: the chromosomes are still actually sister chromatids)

  13. TELOPHASE I • Cytokinesis may occur and two HAPLOID cells containing sister chromatids are produced • A brief period of interkinesis occurs

  14. INTERKINESIS A short interphase like stage between divisions TELOPHASE I PROPHASE II

  15. Fase I Fase II MEIOSIS SEPARATES SISTER CHROMATIDS

  16. PROPHASE II • Nuclear membranes disappear • Nucleoli disappear • Spindle fibers form • Chromatin coils to form chromosomes • What does this remind you of ? • Prophase II is basically the same as mitosis prophase x 2

  17. METAPHASE II • In metaphase II the two cells line up their chromosomes in the middle of the cell in a straight line at equator • Again this is the same as mitosis metaphase - only two cells are doing it • Each cell is doing it with only 1 chromosome of each kind, not pairs

  18. ANAPHASE II • During this phase the centromeres of the chromosomes in the two cells divide and sister chromatids move to opposite poles of the cells • Very mitosis-like again

  19. TELOPHASE II • Final act of meiosis • Nuclear membranes reappear • Nucleoli reappear • Chromosomes uncoil to chromatin • Spindle fibers disappear • Cytokinesis occurs to produce a total of 4 haploid cells (N)

  20. Meiosis : Summary of reduction division

  21. Phases of spermatogenesis (i.e., meiosis in males)

  22. TERIMA KASIH

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