Cell Division: Mitosis

• DNA


  Deoxyribonucleic acid, the molecule that carries the genetic material for the development and functioning of an organism
• RNA


  Ribonucleic acid, a molecule present in the majority of living organisms and viruses, made up of nucleotides
• Chromatids


  The two identical halves of a chromosome that have been replicated in preparation for cell division, joined at the centromere
• Chromosome


  Threadlike structures made of protein and a single molecule of DNA that carry the genomic information from cell to cell
• Interphase


  The preparatory phase for later cell division, where the cell grows, replicates its chromosomes, and prepares for cell division
• Cell division


  1. Mitosis

  2. Meiosis
• Cell cycle


  A series of events that takes place in a cell as it grows and divides
• Interphase


  1. G1 phase

  2. S phase

  3. G2 phase
• Interphase


  • Cell's DNA is copied, each chromosome consists of 2 chromatids attached at a centromere
  • Cell grows rapidly and carries out routine functions, organelles replicate except for DNA
  • Phase takes most of the cell's life, muscle and nerve cells never divide, so they remain in G1
• G2 phase


  • The cell has grown, DNA has been replicated, and now the cell is almost ready to divide, microtubules are used to move chromosomes during mitosis
• As cells absorb nutrients and get larger, the volume of the cell increases faster than the surface area, so the cell must divide
• Cells also divide for repair, replacement, and to prevent cancer
• Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  5. Cytokinesis
• Prophase


  • Chromatids condense becoming visible, nuclear membrane dissolves, centrioles appear and migrate to opposite sides, spindle fibers start to form between them
• Metaphase


  • Chromosomes line-up on the metaphase plate, centromeres are attached to spindle fibers
• Anaphase


  • Spindle fibers contract, centromeres divide, sister chromatids are pulled away from each other towards the poles
• Telophase


  • The chromosomes reach the poles, nuclear membranes form around the 2 new nuclei
• Cytokinesis


  • The cytoplasm is distributed equally between the 2 new cells, in animals a cleavage furrow forms from outside in, in plants a cell plate forms from inside out
• The product of mitosis is 2 cells, the daughter cells are identical to each other and to the mother cell
• In humans, the 2 daughter cells will have 46 chromosomes (23 pairs), each chromosome has the same gene sequence
• Mitosis is a form of asexual reproduction, new individuals are produced by 1 parent and are identical to their parent
• Different cells can be in different stages of mitosis.
• Muscle and nerve cells never divide, so they remain in G1 Phase
• Each chromosome consists of 2 chromatids attached at a centromere
• G1 Phase

  • Cell grows rapidly
  • Organelles replicate (except DNA)
  • Takes most of the Cell's life
  • Muscle and nerve cells stop here
• S Phase

  • Cell's DNA is copied
  • At the end of this stage, each chromosome consists of 2 chromatids attatched at a centromere
• G2 Phase

  • The cell is ready to divide
  • Microtubules are used to move chromosomes during mitosis