Eukaryotes vs Prokaryotes

• Chromosomes in Eukaryotes

  • eukaryotic cells contain membrane-bound organelles, including a nucleus
  • DNA is found in the nucleus, chloroplasts, and mitochondria
  • linear chromosomes
• Chromatin

  • found in eukaryotic cells
  • a complex consisting of DNA and histone proteins organised into a relatively loose coiled form
  • when the cell prepares to divide, the chromatin coils more tightly and becomes visible as chromosomes
• Chromatin to Chromosomes

  1. a nucleosome consists of a section of a DNA molecule looped twice around a core of 8 histone proteins
  2. interacting proteins package loops of coiled DNA (chromatin), which is organised as a cylindrical fibre
  3. chromatin is further condensed to make chromosomes
• Chromosomes in Prokaryotes

  • membrane-bound organelles, such as a nucleus, are NOT present
  • DNA is usually in the form of a single circular chromosome (not bound to histones)
  • chromosomes are found in the nucleoid region
  • plasmids may also be present in the cytoplasm (small rings of DNA that can replicate independently of the main chromosome)
  • contain less DNA