Pembelahan Sel Sistem Reproduksi AP Biology Cell division

Pembelahan Sel & Sistem Reproduksi AP Biology

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? AP Biology

Pembelahan sel secara meiosis AP Biology

How does corn make sperm & egg? § reduce 20 chromosomes 10 chromosomes u half the number of chromosomes 10 20 10 Egg nuclei meiosis 20 AP Biology 20 10 10 Sperm nuclei fertilization

Meiosis: menghasilkan gamet § Alternating processes, alternating stages u chromosome number must be reduced § diploid haploid § meiosis reduces chromosome number u fertilization restores chromosome number § haploid diploid § n 2 n AP Biology

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

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

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

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

Preparing for meiosis § 1 st division of meiosis separates homologous pairs synapsis tetrad AP Biology 2 n = 4 single stranded prophase 1 2 n = 4 double stranded metaphase 1 2 n = 4 double stranded telophase 1 1 n = 2 double stranded

Meiosis 2 § 2 nd division of 1 n = 2 double stranded meiosis separates sister chromatids What does this division look like? prophase 2 1 n = 2 double stranded metaphase 2 1 n = 2 single stranded AP Biology telophase 2

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

Mitosis vs. Meiosis AP Biology

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

Pindah Silang (Crossing over) § Selama Prophase 1 Bagian pasangan homolog berganda u sister chromatid bersentuhan u crossing over u tetrad AP Biology synapsis

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

§ Pindah Silang u AP Biology Membentuk kombinasi sifat bawaan baru pada generasi berikutnya

Apa kelemahan reproduksi seksual? Atau ada pertanyaan ? ? AP Biology