6 : Cell Division

Cards (32)

  • Before cell division occurs, chromosomes appears as thread-like structures knows as chromatin.
  • Interphase consists of three stages: G1 phase, S phase, and G2 phase.
  • The process of mitosis involves four stages: prophase, metaphase, anaphase, and telophase.
  • Chromatin consists of single DNA strand and proteins.
  • Chromatin cannot be seen under microscope.
  • Karyokinesis involves the division of the nucleus.
  • Cytokinesis involves the division of the cytoplasm.
  • Somatic cells are produced through mitosis process.
  • Gametes are produced through the meiosis process.
  • Somatic cells contains a diploid number of chromosomes, 2n = 46 ( in human )
  • Gametes contains haploid number of chromosomes, n = 23 ( in human ).
  • A pair of paternal and maternal chromosomes are called homologous chromosomes.
  • Interphase is the longest phase in the cell cycle.
  • What happens during G1 phase?
    • Cell grows
    • Cell multiplies the number of organelles in the cytoplasm
  • What happens during S phase?
    • DNA replication
    • Each chromosome multiplies into two identical chromosomes (sister chromatids)
    • Both chromatids are joined at the centromeres
    • Multiplication of centriole
  • What happens during G2 phase?
    • Cell continues to grow
    • More proteins and enzymes are synthesised
    • Cell pepares to divide
  • What happens during M phase?
    Cell divisionprophase, metaphase, anaphase, telophase
  • Mitosis is defined as the division of the nucleus of parent cell into two division in somatic nuclei.
  • In prophase, chromatin starts to shorten and thicken.
  • The chromosome in prophase is made up of two identical threads called sister chromatids.
  • During prophase, the nucleus membrane disintegrates, nucleolus disappears, centriole moves to the opposite poles and spindle fibres start to form.
  • In metaphase, the chromosomes lined up on the equatorial plane.
  • During metaphase, spindle fibres maintain the chromosomes at the equatorial plane.
  • Metaphase ends when the centromere begins to divide.
  • The centromere divides into two and the sister chromatids separate during anaphase.
  • In anaphase, the spindle fibres shorten, contract and pull the sister chromatids to opposite poles.
  • Anaphase ends when the chromatid arrives at the pole of the cell.
  • Chromosomes are shaped again as fine chromatin threads at the start of telophase.
  • Nucleoli reforms and spindle fibres disappear during telophase.
  • New nucleus membrane reforms to surround the new daughter chromosomes in telophase.
  • The telophase stage is followed by cytokinesis to form two daughter cells.
  • Mitosis in plant cells does not require the presence of centrioles for formation of spindle fibres. Instead, they separate using a new cell wall.