pembelahan sel
TRANSCRIPT
![Page 1: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/1.jpg)
YANTI PUSPITA SARI
![Page 2: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/2.jpg)
Kontinuitas kehidupanDidasarkan atas reproduksi sel atau pembelahan sel
![Page 3: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/3.jpg)
Semua organisme kompleks berasal dari a single fertilized egg.
Melalui pembelahan sel, jumlah sel meningkat
Sel kemudian terspesialisasi dan berubah menjadi fungsinya masing2
![Page 4: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/4.jpg)
![Page 5: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/5.jpg)
Pembelahan sel mempunyai tujuan sbb :
◦ Regenerasi sel-sel yang rusak/mati
◦ Pertumbuhan dan perkembangan
◦ Berkembang biak (reproduksi)
◦ Variasi individu baru
![Page 6: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/6.jpg)
Pembelahan Sel (Reproduksi Sel)Amitosis : - Pembelahan sel secara langsung - terjadi pada sel prokaryot (bakteri, alga biru) - sel anak sama dengan sel indukMitosis : - Pembelahan sel melalui beberapa tahap (prophase, metaphase, anaphase dan telophase), - terjadi pada sel tubuh/Somatik - sel anak sama dengan sel induk Meiosis : - pembelahan sel melalui beberapa tahap (prophase, metaphase, anaphase dan telophase) - terjadi pada sel gamet (spermatogenesis,
oogenesis) - sel anak bersifat haploid (setengah dari kromosom
Induk)
![Page 7: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/7.jpg)
Pembelahan Amitosis
Pembelahan sel pada Eschericia coli
FOTO : TEM FOTO : SEM
![Page 8: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/8.jpg)
![Page 9: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/9.jpg)
Pembelahan sel pada eukariot terdiri dari:◦ Mitosis, the division of the nucleus◦ Cytokinesis, the division of the cytoplasm
Gamet diproduksi dalam pembelahan sel yang disebut meiosis
Meiosis menghasilkan sel anak yang tidak identik dengan induk yaitu hanya memiliki 1 set kromosom
![Page 10: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/10.jpg)
0.5 µm
Chromosomeduplication(including DNA synthesis)
Centromere
Separation of sister chromatids
Sisterchromatids
Centromeres Sister chromatids
A eukaryotic cell has multiplechromosomes, one of which is
represented here. Before duplication, each chromosome
has a single DNA molecule.
Once duplicated, a chromosomeconsists of two sister chromatids
connected at the centromere. Eachchromatid contains a copy of the
DNA molecule.
Mechanical processes separate the sister chromatids into two chromosomes and distribute
them to two daughter cells.
Figure 12.4
![Page 11: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/11.jpg)
Siklus sel
Interphase
G1 phase
Primary cell growth phase
S phase
DNA replication
G2 phase
Microtubule synthesis
Mitosis
Nuclear division
Cytokinesis
Cytoplasmic division
![Page 12: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/12.jpg)
Diatur pada checkpoint” tertentu Checkpoint : titik pengontrolan yang kritis
dimana sinyal berhenti dan sinyal terus dapat mengatur siklus.
Tdp 3 checkpoint yaitu pada G1, G2,M- Pada G1 : dianggap sbg titik restriksi (pembatasan) dlm sel. Jika sel menerima sinyal terus dari checkpoint G1, sel akan menyelesaikan siklusnya dan membelah. Jika tdk, sel keluar dari siklus dan beralih ke keadaan tidak membelah (fase G0)- Protein kinase tertentu memberi sinyal terus pada checkpoint G1 dan G2
![Page 13: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/13.jpg)
- Kinase dalam sel dlm bentuk tdk aktif. Agar aktif kinase harus dilekatkan pd siklin (suatu protein) _____ kinase tergantung siklin (cyclin dependent kinase – Cdk)
- Cdk –siklin yg pertama kali ditemukan MPF (maturation promoting factor) : memicu jalan sel melewati checkpoint G2 ke fase M.
Pada akhir fase M, MPF akan membantu meng-off-kan dirinya dgn menginisiasi proses yg mengarah ke pengrusakan siklinnya oleh enzim proteolitik (penghidrolisis protein).
![Page 14: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/14.jpg)
The sequential events of the cell cycle◦ Are directed by a distinct cell cycle control system,
which is similar to a clock
Figure 12.14
Control system
G2 checkpoint
M checkpoint
G1 checkpoint
G1
S
G2M
![Page 15: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/15.jpg)
The clock has specific checkpoints◦Where the cell cycle stops until a go-ahead
signal is received
G1 checkpoint
G1G1
G0
(a) If a cell receives a go-ahead signal at the G1 checkpoint, the cell continues on in the cell cycle.
(b) If a cell does not receive a go-ahead signal at the G1checkpoint, the cell exits the cell cycle and goes into G0, a nondividing state.
Figure 12.15 A, B
![Page 16: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/16.jpg)
![Page 17: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/17.jpg)
![Page 18: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/18.jpg)
• The mitotic spindle– mikrotubul yang mengontrol pergerakan kromosom
selama mitosis
• Spindle muncul dari sentrosom– spindle microtubules – asters
![Page 19: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/19.jpg)
Perakitan spindle microtubules dimulai dari sentrosom - microtubule organizing center
Sentrosom bereplikasi membentuk dua sentrosom yang bermigrasi ke kutub yang berlawanan, dan spindle microtubules tumbuh dari sentrosom
Aster (a radial array of short microtubules) muncul dari tiap sentrosom
![Page 20: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/20.jpg)
Some spindle microtubules◦ Berikatan dengan kinetochores chromosomes
CentrosomeAster
Sisterchromatids
MetaphasePlate
Kinetochores
Overlappingnonkinetochoremicrotubules
Kinetochores microtubules
Centrosome
ChromosomesMicrotubules 0.5 µm
1 µm
Figure 12.7
![Page 21: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/21.jpg)
![Page 22: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/22.jpg)
![Page 23: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/23.jpg)
![Page 24: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/24.jpg)
◦Prophase◦Prometaphase
G2 OF INTERPHASE PROPHASE PROMETAPHASE
Centrosomes(with centriole pairs) Chromatin
(duplicated)
Early mitoticspindle
AsterCentromere
Fragmentsof nuclearenvelope
Kinetochore
Nucleolus Nuclearenvelope
Plasmamembrane
Chromosome, consistingof two sister chromatids
Kinetochore microtubule Figure 12.6
Nonkinetochoremicrotubules
![Page 25: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/25.jpg)
![Page 26: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/26.jpg)
![Page 27: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/27.jpg)
◦Metaphase◦Anaphase◦Telophase
Centrosome at one spindle pole
Daughter chromosomes
METAPHASE ANAPHASE TELOPHASE AND CYTOKINESIS
Spindle
Metaphaseplate Nucleolus
forming
Cleavagefurrow
Nuclear envelopeforming
Figure 12.6
![Page 28: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/28.jpg)
![Page 29: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/29.jpg)
Pada sel hewan◦ Cytokinesis terjadi oleh proses yang disebut cleavage,
membentuk sebuah a cleavage furrow (alur pembelahan)
Cleavage furrow
Contractile ring of microfilaments Daughter cells
100 µm
(a) Cleavage of an animal cell (SEM)
![Page 30: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/30.jpg)
Pada sel tumbuhan, selama cytokinesis◦ Terbentuk plat sel (cell plate)
Daughter cells
1 µmVesiclesforming cell plate
Wall of patent cell Cell plate New cell wall
(b) Cell plate formation in a plant cell (SEM)Figure 12.9 B
![Page 31: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/31.jpg)
Mitosis in a plant cell
1 Prophase. The chromatinis condensing. The nucleolus is beginning to disappear.Although not yet visible in the micrograph, the mitotic spindle is staring to from.
Prometaphase.We now see discretechromosomes; each consists of two identical sister chromatids. Laterin prometaphase, the nuclear envelop will fragment.
Metaphase. The spindle is complete,and the chromosomes,attached to microtubulesat their kinetochores, are all at the metaphase plate.
Anaphase. Thechromatids of each chromosome have separated, and the daughter chromosomesare moving to the ends of cell as their kinetochoremicrotubles shorten.
Telophase. Daughternuclei are forming. Meanwhile, cytokinesishas started: The cellplate, which will divided the cytoplasm in two, is growing toward the perimeter of the parent cell.
2 3 4 5
NucleusNucleolus
ChromosomeChromatinecondensing
Figure 12.10
![Page 32: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/32.jpg)
Berbeda-beda pada beberapa jenis sel yang berbeda
Beberapa sel membelah cepat, sel lain membutuhkan waktu yang lebih lama
Sel kanker pembelahan cepat, sel anakan akan terus membelah sebelum dewasa secara fungsonal
![Page 33: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/33.jpg)
Pertumbuhan dan metastasis tumor ganas pada payudara
Cancer cells invade neighboring tissue.
2 A small percentage of cancer cells may survive and establish a new tumor in another part of the body.
4Cancer cells spread through lymph and blood vessels to other parts of the body.
3A tumor grows from a single cancer cell.
1
Tumor
Glandulartissue
Cancer cell
Bloodvessel
Lymphvessel
MetastaticTumor
Figure 12.19
![Page 34: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/34.jpg)
![Page 35: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/35.jpg)
Centrosomes(with centriole pairs)
Sisterchromatids
Chiasmata
Spindle
Tetrad
Nuclearenvelope
Chromatin
Centromere(with kinetochore)
Microtubuleattached tokinetochore
Tertads line up
Metaphaseplate
Homologouschromosomesseparate
Sister chromatidsremain attached
Pairs of homologouschromosomes split up
Chromosomes duplicateHomologous chromosomes
(red and blue) pair and exchangesegments; 2n = 6 in this example
INTERPHASE MEIOSIS I: Separates homologous chromosomes
PROPHASE I METAPHASE I ANAPHASE I
Interphase and meiosis I
Figure 13.8
![Page 36: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/36.jpg)
PADA MIOSIS I, I. fase profase tdd:
a. Leptoten : kromatin berkondensasi menjadi kromosom, bgn ujung msg”melekat ke selaput inti (plaque), kromosom mengganda jd 2 tp sentromer ttp satub. Zigoten : kromosom homolog bersinapsis, lengan setiap kromatid sdh merenggang shg kromosom homolog tampak tdd serangkaian 4 / tetrad.Sinapsis: pergandengan kromosom homolog- Pd bbrp tmp tjd persilangan antara kromosom yg bergandengan (chiasma)Persilngan dibbrp tmp : chiasmata
![Page 37: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/37.jpg)
c. Pakhiten : tjd chisma disusul dgn tjdnya pindah silang (crossing over) antara kromosom homolog.
d. Diploten : pergandengan kromosom homolog merenggang meskipun msh tjd chiasma dibbrp tmp (tjd aktivitas transkripsi yg meningkat utk sintesa RNA
e. Diakenesis : kromosom makin berkondensasi, ujung”nya lepas dari selaput inti. Transkripsi berhenti. Chiasma msh tjd antara kromosom homolog. Selaput inti hancur, terbentuk serat gelendong (mikrotubul)
![Page 38: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/38.jpg)
Kromosom bergerak ke bid ekuator, kromosom homolog ttp bergandengan, chiasma tdk ada, selaput inti hilang, serat gelendong terbentuk sempurna.
III. Anafase : kromosom homolog berpisah, bergerak ke kutub bersebrangan. Chiasma dan pindah silang selesai dan terlepas
IV. Telofase : Tjd Cytokenesis shg terbentuk 2 sel, msg”dgn 1 inti dgn sebelah kromosom homolog. Tiap kromosom tdd 2 kromatid yg centromernya msh bergabung. Terbentuk selaput inti
![Page 39: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/39.jpg)
a. Profase : wkt singkat, mikrotubul terbentuk. Kromosom tersebar di kutub bersebrangan (kromosm tdk mengganda)
b. Metafase : kromosom pindah ke bidang ekuator
c. Anafase: Kromatid berpisah, msg”dgn sentromer sendiri bergerak ke kutub berlawanan. Disini terbentuk kromosom hasil rekombinasi
d. Telofase : Kromosom mengalami dekondensasi mjd kromatindan terbentuk selaput inti disekeliling kromatin. Tjd cytokenesis shg terbentuk 4 sel
![Page 40: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/40.jpg)
TELOPHASE I ANDCYTOKINESIS
PROPHASE II METAPHASE II ANAPHASE II TELOPHASE II ANDCYTOKINESIS
MEIOSIS II: Separates sister chromatids
Cleavagefurrow Sister chromatids
separate
Haploid daughter cellsforming
During another round of cell division, the sister chromatids finally separate;four haploid daughter cells result, containing single chromosomes
Two haploid cellsform; chromosomesare still doubleFigure 13.8
Telophase I, cytokinesis, and meiosis II
![Page 41: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/41.jpg)
Pembelahan Meiosis
Interphase Prophase I Metaphase I Anaphase I Telophase I
Prophase II Metaphase II Anaphase II Telophase II
![Page 42: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/42.jpg)
![Page 43: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/43.jpg)
![Page 44: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/44.jpg)
Karakteristik Mitosis Meiosis
Tipe sel yang membelah
Sel somatik Sel gamet
Kromosom sel anak
2n (diploid) n kromosom (haploid)
Sifat sel anak Sama dengan induk
Bervariasi dari induk
Jumlah sel anak 2 sel 4 sel
Bangaknya pembelahan
1 kali 2 kali
Tujuan pembelahan
Memperbanyak jumlah sel
Keanekaragaman/variasi
Perbandingan Mitosis dan Meiosis
![Page 45: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/45.jpg)
Gangguan Pembelahan Meiosis Kesalahan selama pembelahan meiosis dapat
merubah :1. Jumlah kromosom per sel2. Struktur tiap kromosom
Kedua kesalahan diatas bisa berakibat pada fenotip (sifat yang muncul pada individu).
Ad 1 : Terdapat 2 gangguan jumlah kromosom : 1. Aneuploid
Trisomik (2n+1) Monosomik (2n-1) 2. Poliploid
Triploid (3n) Tetraploid (4n)
![Page 46: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/46.jpg)
◦ Delesi◦ Duplikasi◦ Inversi◦ Translokasi
a. Delesi
![Page 47: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/47.jpg)
b. Duplikasi
![Page 48: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/48.jpg)
c.Inversi
![Page 49: Pembelahan Sel](https://reader035.vdokumen.com/reader035/viewer/2022062221/55cf98e7550346d0339a5a88/html5/thumbnails/49.jpg)
d. Translokasi