CELL CYCLE AND MITOSIS

• The ability of organisms to produce more of their own kind best distinguishes living things from nonliving matter
• The continuity of life is based on the reproduction of cells, or cell division
• In unicellular organisms, division of one cell reproduces the entire organisms
• Multicellular eukaryotes depend on cell division for

  • Development from a fertilized egg
  • Growth
• Most cell division results in genetically identical daughter cells
• All DNA in the cell is called the genome 
• DNA are packaged into chromosomes
• DNA complexes with protein

  chromatin
• Super-coiled chromatin is called chromosome
• Somatic cells are non-reproductive
• Gametic cells are sperms and egg
• When DNA is copied, it is called replication
• The copy of a chromosome is called a sister chromatid
• The centromere is where two chromatids are most closely attached
• The centromere is separated in anaphase and chromatids become full fledged chromosomes
• Mitosis is the division of genetic material in the nucleus
• Cytokinesis is the division of cytoplasms
• Gametes are produced by a variation of cell division called meiosis
• Meiosis yields nonidentical daughter cells that have half as many chromosomes as the parent cell
• Mitotic phase alternates with interphase in the cell cycle
• Phases of the Cell Cycle

  • M phase
  • Interphase
• Interphase comprises 90% of the cell cycle
• Cell grows during all three phases, but chromosomes are duplicated only during S phase
• Interphase

  • G1
  • Synthesis 
  • G2
• Mitosis

  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase
• Mitotic spindle is made of microtubules
• Centromeres + microtubule = kinetochore
• The mitotic spindle is a structure made of microtubules that controls chromosome movement during mitosis
• In animal cells, assembly of spindle microtubules begins in the centrosome, the microtubule-organizing center
• The centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase
• Asters are short microtubules at poles
• Spindle microtubules are microtubules going towards the spindle
• Kinetochores are protein complexes associated with centromeres
• Depolymerization is the disassembly of microtubules at kinetochore ends
• For plant cells, separation of cytoplasms starts from center and goes towards the outside and forms the cell plate
• In telophase for plants, a faint line starts at the middle then moves towards the outside
• Binary fission is when prokaryotes perform cell division
• Binary fission progresses continuously
• Binary fission involves the inward pinching for prokaryotes
• Mitosis evolved from binary fission in prokaryotes