REPRODUKSI SEL

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REPRODUKSI SEL
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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
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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
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REPRODUKSI SEL

• MITOSIS ? sel somatik
• MEIOSIS ? sel seks atau gamet (spermatozoa dan
  ovum)

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MITOSIS
Interfase
Metafase
Anafase
Profase
Telofase

1. Terjadi sintesis protein kromatin dan inti
   nampak jelas replikasi DNA
2. Kromatin tebal ? kromosom membran inti melebur
   sentriol bergerak pada sisi yang berlawanan dan
   serabut spindel mulai terbentuk
3. Kromosom yang dihubungkan spindel ada di tengah
4. Kromosom memisah menuju ke kutub yang berlawanan
5. Kromosom kembali berbentuk kromatin speindel
   melebur membran inti nampak sentriol replikasi
   terbentuk membran sel baru

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

• Terdiri dari 2 fase
• Meiosis I merupakan pembelahan yang memisahkan
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• 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

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PROPHASE I

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

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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
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CROSSING -OVER

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

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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

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ANAPHASE I

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

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TELOPHASE I

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

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INTERKINESIS
A short interphase like stage between
divisions
TELOPHASE I
PROPHASE II
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MEIOSIS
SEPARATES SISTER CHROMATIDS
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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

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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

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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

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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)

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MEIOSIS II
PROPHASE II
MEIOSIS II
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Meiosis Summary of reduction division
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Phases of spermatogenesis (i.e., meiosis in
males)
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TERIMA KASIH