Transcript
Pembelahan Sel II : Meiosis
Reproduksi Seksual : Meiosis
Tjd pada sel gamet ( sel ovum & sel sperma) Meiosis mereduksi jumlah kromosom dr diploid
menjadi haploid Pembelahan sel tjd 2 kali 4 sel anak
memiliki kromosom setengah dr sel induk
Meiosis 1
Saat tjd pembelahan pertama (meiosis 1), kromosom homolog berpasangan
Selama kromosom homolog b'pasangan terjadi pertukaran genetik (CROSS OVER)
Pasangan kromosom homolog b'pisah & menghasilkan 2 sel anak
Meiosis 1
MEIOSIS I: Homologous chromosomes separate
INTERPHASE PROPHASE I METAPHASE I ANAPHASE I
Centrosomes(withcentriolepairs)
Nuclearenvelope
Chromatin
Sites of crossing over
Spindle
Sisterchromatids
Tetrad
Microtubules attached tokinetochore
Metaphaseplate
Centromere(with kinetochore)
Sister chromatidsremain attached
Homologouschromosomes separate
Meiosis II
Meiosis 2 pada intinya sama dengan mitosis: Sister kromatid pada masing2 kromosom
b'pisah Menghasilkan 4 sel anak yg haploid
Meiosis II
MEIOSIS II: Sister chromatids separate
TELOPHASE IAND CYTOKINESIS PROPHASE II METAPHASE II ANAPHASE II
Cleavagefurrow
Sister chromatidsseparate
TELOPHASE IIAND CYTOKINESIS
Haploiddaughter cellsforming
Review: Perbandingan Mitosis & Meiosis
Figure 8.15
MITOSIS MEIOSIS
PARENT CELL(before chromosome replication)
Site ofcrossing over
MEIOSIS I
PROPHASE ITetrad formedby synapsis of homologous chromosomes
PROPHASE
Duplicatedchromosome(two sister chromatids)
METAPHASE
Chromosomereplication
Chromosomereplication
2n = 4
ANAPHASETELOPHASE
Chromosomes align at the metaphase plate
Tetradsalign at themetaphase plate
METAPHASE I
ANAPHASE ITELOPHASE I
Sister chromatidsseparate duringanaphase
Homologouschromosomesseparateduringanaphase I;sisterchromatids remain together
No further chromosomal replication; sister chromatids separate during anaphase II
2n 2n
Daughter cellsof mitosis
Daughter cells of meiosis II
MEIOSIS II
Daughtercells of
meiosis I
Haploidn = 2
n n n n
Review:Perbandingan Mitosis & Meiosis
Kejadian Mitosis Meiosis
Replikasi DNA Tjd 1 kali selama interfase sblm pembelahan nukleus dimulai
Tjd 1 kali selama interfase sblm meiosis 1 dimulai
Jumlah pembelahan 1 kali : Profase, metafase, anafase & telofase
2 kali, masing2 tmsk Profase, metafase, anafase & telofase
Sinapsis kromosom homolog
Tidak terjadi Tjd pd profase 1: kromosom homolog bergabung m'btk tetrad (kel.4 kromatid), tjd pindah silang (cross over)
Jumlah sel anak & komposisi genetik
2, masing2 diploid (2n), identik dgn sel indul
4, haploid, mengandung separuh jumlah kromosom sel induk, tdk identik dgn sel induk
Peran dlm tubuh Mjd organisme dewasa multiseluler, m'hsl sel utk pertumbuhan & perbaikan jaringan
M'hsl gamet , mengurangi jumlah kromosom separuh nya & tjd variabilitas genetik diantara gamet
MEIOSIS PADA MANUSIA
GOOD LUCK & ENJOY YOUR STUDY
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