Cell Division

• Chromosome is made of group of DNA molecule by protein and histone to form number package of chromosome
• Why chromosome is necessary to DNA?

  So DNA can be organized and accommodated inside the eukaryotic cell
• Nucleosome- composed of globular structure known as histone where DNA attached
• A pack of nucleosome is called solenoid
• A pack of solenoid is called chromatin loops
• How many cell cycle are there?

  2
• What are the cell cycle?

  Interphase and Mitotic
• Interphase

  •interval between two cell division

  •cell not dividing; taking nutrients, growing, replicate DNA
• G1

  •cells grows initially

  •syntesis of RNA and protein

  •Mitochodria increases
• S phase

  •DNA replication for replicating the chromosome
• G2

  •Cells grow rapdily
• Where Mitosis happen?

  Body cells or semantic cells
• What happen to the chromosome in Mirotic phase?

  Become thick and short
• Metaphase

  •Chromatids allign

  •the spider fiber connectconnect to the chromosome kinetechore
• Anaphase

  •spinder fiber began to contract and become smaller. The continually of contraction will seperate the chromatids

  •the centromere divide

  •the chromatids go to the opposite poles
• Telophase

  •the chromatids are in the opposite poles

  •microtubules dissapear

  •the chromosome are in new nuclear membrane, in process of karyokinosis

  •cytoplasmatic division called cytokines are in process, spliting the chromatids
• What mitosis produce?

  2 nuclear membrane and nuclei and forms 2 new daughter cells
• Where does miosis occur?

  Sex cells
• Before miosis- sex cells is in the interphase, whereby DNA replicate then, the sex cells will undergo cell growth called interkineses. Happen in Miosis 1 and 2 however it does not form a DNA replicate
• Miosis 1

  •division reduction phase (diploid-haploid)

  •forms 2 daughter cells with 23 chromosome
• Prophase


  1. Leptotene

  2. Zygotene

  3. Pachytene

  4. Diplotene

  5. Diakenesis
• Leptotene


  Each chromosome are made of sister chromatid which replicate in S phase
• Zygotene

  The tetrad will start to pair off in the process called synopsis
• Pachytene


  The repeating coiling of chromosome, contracting the chromatids making the tetrads very close to each other. Here crosscross over happen where the segment of chromosome exchange in the process of chiasma. The sister chromatida might not be identical to each other
• Diplotene


  The chromosome will start to go to the opposite. The chiasma are the one holding them together
• Diakenesis


  1. The dividing cell will start metaphase

  2. Breakdown of nucleosome and membrane

  3. Chiasma move toward termination
• Metaphase 1

  •the tetrad alright

  •the spindle fiber connect to the chromosome kinetochore
• Anaphase 1

  •the spindle fiber began to contract and seperate the tetrads

  •the tetrads movesmoves in the opposite pole
• Telophase 1

  •reform of membrane

  •cytokineses happen, forming two cells and two sister chromatids