Prokaryotic and Eukaryotic Cells

• The 2 main types of cell

  • Prokaryotic 
  • Eukaryotic
• Plant , animal and fungal cells are all eukaryotic
• Bacterial cells are prokaryotic
• Features of a eukaryotic cell

  • Eukaryotic cells are larger in size than prokaryotic cells 
  • Their genetic material is enclosed in a nucleus 
  • They do contain mitochondria or chloroplasts

  
• Features of a prokaryotic cell

  • Prokaryotic cells are smaller in size than eukaryotic cells 
  • Their genetic material is not enclosed in a nucleus 
  • Their genetic material consists of a single loop of DNA , and may also have small rings of DNA called plasmids 
  • They do not contain mitochondria or chloroplasts

  
• The DNA of bacteria is not found within a nucleus and is usually found as one circular chromosome
• The role of cell wall in a bacterial cell

  It provides structural support to the bacteria - the cell wall is not made of celluose
• The role of the flagella in a bacterial cell

  It is a tail-like structure that rotates to help the bacteria move
• Bacterial cells have many different shapes - some are round , some are rod-shaped and some are spiral - but they are all prokaryotic cells
• In bacterial cells, the roles of mitochondria and chloroplasts are taken over by the cytoplasm
• The role of plasmids in a bacterial cell

  • Plasmids are present in bacterial cells , and they are circles of DNA that can be transferred from one cell to another 
  • Plasmids allow bacterial cells to move genes from one cell to another 
  • Plasmids can replicate independently of chromosomal DNA
• What came first : Prokaryotic or Eukaryotic cells

  • Prokaryotic cells are much simpler in structure than eukaryotic cells 
  • That is why scientists think that they developed before eukaryotic cells
• Scientists using plasmids

  • Plasmids very useful to scientists 
  • They allow genes to be inserted into bacteria in genetic engineering