Pembelahan Sel & Sistem Reproduksi.

Presentasi berjudul: "Pembelahan Sel & Sistem Reproduksi."— Transcript presentasi:

1 Pembelahan Sel & Sistem Reproduksi

2 Cell division / Reproduksi Asexual
Mitosis Menghasilkan sel dengan informasi sama identical daughter cells Selnya sama betul (exact copies) clones Jumlah DNA sama Jumlah chromosome sama Informasi genetik sama Peran : pertumbuhan dan perkembangan organisme Apa kebaikan reproduksi aseksual?

3 Pembelahan sel secara meiosis

4 How does corn make sperm & egg?
reduce 20 chromosomes  10 chromosomes half the number of chromosomes 10 20 10 20 Egg nuclei 10 meiosis 20 10 fertilization Sperm nuclei

5 Meiosis: menghasilkan gamet
Alternating processes, alternating stages chromosome number must be reduced diploid  haploid meiosis reduces chromosome number fertilization restores chromosome number haploid  diploid n  2n

6 Chromosome Homologous
Chromosome Berpasangan Pasangan chromosome yang membawa gen sama Mengatur sifat bawaan yang sama homologous = sama informasi diploid 2n Chromosom homolog Pasangan ganda chromosom homolog

7 Making gametes for the next generation
- 2 copies - diploid - 2n - 1 copy - haploid - 1n

8 Double division of meiosis
Replikasi DNA 1st division of meiosis separates homologous pairs 2nd division of meiosis separates sister chromatids

9 Menjelang meiosis 1st step of meiosis Duplikasi DNA Why bother?
meiosis evolved after mitosis convenient to use “machinery” of mitosis DNA disintesis pada fase S saat interphase MEIOSIS 2n = 6 single stranded 2n = 6 double stranded M1 prophase

10 2n = 4 single stranded Preparing for meiosis 1st division of meiosis separates homologous pairs 2n = 4 double stranded prophase1 2n = 4 double stranded metaphase1 synapsis telophase1 tetrad 1n = 2 double stranded

11 What does this division look like?
Meiosis 2 2nd division of meiosis separates sister chromatids 1n = 2 double stranded What does this division look like? prophase2 1n = 2 double stranded metaphase2 1n = 2 single stranded telophase2

12 Steps of meiosis Meiosis 1 Meiosis 2 interphase prophase 1 metaphase 1
anaphase 1 telophase 1 Meiosis 2 prophase 2 metaphase 2 anaphase 2 telophase 2 1st division of meiosis separates homologous pairs (2n  1n) 2nd division of meiosis separates sister chromatids (1n  1n) * just like mitosis *

13 Mitosis vs. Meiosis

14 Mitosis vs. Meiosis Mitosis Meiosis 1 division
daughter cells genetically identical to parent cell produces 2 cells 2n  2n produces cells for growth & repair no crossing over Meiosis 2 divisions daughter cells genetically different from parent produces 4 cells 2n  1n produces gametes crossing over

15 Pindah Silang (Crossing over)
Selama Prophase 1 Bagian pasangan homolog berganda sister chromatid bersentuhan crossing over tetrad synapsis

16 Crossing over 3 steps Kombinasi sifat baru cross over (pindah silang)
breakage of DNA (Pemutusan gugus DNA) re-fusing of DNA (Penyambungan gugus DNA) Kombinasi sifat baru

17 Pindah Silang Membentuk kombinasi sifat bawaan baru pada generasi berikutnya

18 Apa kelemahan reproduksi seksual? Atau ada pertanyaan ??