Chapter 3 - Cell replication

• Students model the processes involved in cell replication, including but not limited to:

  • mitosis and meiosis (ACSBL075) CCT ICT
  • DNA replication using the Watson and Crick DNA model, including nucleotide composition, pairing and bonding (ACSBL076, ACSBL077)
• Students assess the effect of the cell replication processes on the continuity of species (ACSBL084) ICT
• Biology Stage 6 Syllabus © NSW Education Standards Authority for and on behalf of the Crown in right of the State of New South Wales, 2017
• Inquiry question


  How important is it for genetic material to be replicated exactly?
• Have you ever wondered why it is so important for genetic material to be replicated exactly? Each living creature has a different genetic code that carries instructions for its own production. How do the genetic instructions for wombats differ from those for koalas, dogs, penguins or even mushrooms? Parents give rise to offspring of the same species, with a similar genetic makeup to their own, so they can survive in the same environment. It is essential that organisms pass on their own unique genetic instructions or information from one generation to the next, to ensure the continuity of the species.
• How can something as tiny as a cell carry all the instructions needed to make a large, complex, living organism? When scientists began searching for the 'code of life' in cells, they realised that the genetic code would need to be in molecular form to be small enough to fit all the instructions into a cell. As chromosomes are composed of DNA (deoxyribonucleic acid) and protein, scientists deduced that the genetic code must be carried by one of these two macromolecules – either in proteins or in DNA.
• It was expected that the genetic code would be complex, because it needs to store large amounts of information accurately over long periods of time. The genetic code would also need to be copied exactly and any errors that arose during copying would need to be easily fixed. Most scientists favoured protein as the carrier of the genetic instructions, because proteins are complex and varied, being made up of at least twenty different amino acids.
• Students


  • Model the processes involved in cell replication, including but not limited to:
  • Mitosis and meiosis (ACSBL075) CCT ICT
  • DNA replication using the Watson and Crick DNA model, including nucleotide composition, pairing and bonding (ACSBL076, ACSBL077)
• Students


  • Assess the effect of the cell replication processes on the continuity of species (ACSBL084) ICT
• Biology Stage 6 Syllabus © NSW Education Standards Authority for and on behalf of the Crown in right of the State of New South Wales, 2017
• Each living creature has a different genetic code that carries instructions for its own production
• Parents give rise to offspring of the same species, with a similar genetic makeup to their own, so they can survive in the same environment
• It is essential that organisms pass on their own unique genetic instructions or information from one generation to the next, to ensure the continuity of the species
• Chromosomes are composed of DNA (deoxyribonucleic acid) and protein
• The genetic code must be carried by one of these two macromolecules – either in proteins or in DNA
• The genetic code would need to be copied exactly and any errors that arose during copying would need to be easily fixed
• Most scientists favoured protein as the carrier of the genetic instructions, because proteins are complex and varied, being made up of at least twenty different amino acids
• In 1953, James Watson and Francis Crick discovered the structure of DNA and how it held the 'code of life'
• Genetic information can be carried by a molecule that uses an 'alphabet' made up of only four 'letters': the bases adenine (A), cytosine (C), guanine (G) and thymine (T)
• In the decade following 1953, the combined work of many scientists led to an understanding of how the information in DNA can lead to specific proteins being produced
• Cell division


  Mitosis and meiosis
• Mitosis


  Cell division that leads to the formation of two new identical cells that contribute to the growth of the organism
• Meiosis


  Cell division that gives rise to gametes that transmit genetic material from one generation to the next during sexual reproduction
• Mitosis


  • Growth of multicellular organisms
  • Repair of damaged tissue and replacement of worn-out cells
  • Asexual reproduction
  • Genetic stability
• Embryonic stem cells


  Pluripotent cells that have the potential to develop into any type of tissue
• Adult stem cells


  Pre-specialised cells that can only make certain types of tissue
• Meristem


  Plant tissue that can divide to form any other tissue
• Meiosis

  Cell division that occurs in the sexual reproductive organs of a plant or animal, and results in the formation of gametes (sex cells)