Body plan

• Body plan


  • general structure of an organism
  • development is controlled by proteins
  • these proteins are coded for by homeobox genes
• homeodomain - amino acids

  sequence of 60 amino acids that is the same for all proteins coded for by homeobox genes
• Homeobox region - in the DNA

  sequence of 180 nucleotides, within the larger gene, that is the same for all homeobox genes
• Homeodomain


  • binds to specific sites on DNA
  • works as a transcription factor
  • binds to the start of developmental genes
  • alters the production of proteins involved in the development of the body plan
• What homeobox genes control

  • polarity (head and tail ends)
  • symmetry
  • segmentation
  • positioning of organs
  • regulate and manage apoptosis and mitosis
• Homeobox genes are present (and similar between)

  • plants
  • animals
  • fungi
• Homeobox genes and mutations

  • mutations would lead to an effect on many genes
  • leads to a large effect on the body plan
  • mutations aren't usually passed on as their effects are usually lethal
• Homeobox genes are highly conserved

  they haven't changed much through evolution
• Homeobox genes activate different things from one species to another

  Due to mutations over time