Gram negative and Gram positive bacteria

• Gram negative bacteria

  • don't retain the gram stain (crystal violet) when washed with acetone and absolute alcohol (pink)
  • due to the cell wall having an outer layer
• Gram negative bacteria structure

  • plasma membrane
  • thin cell wall
  • outer membrane
• Gram positive bacteria

  • does retain the gram stain (purple)
  • due to the thick pepticdoglycan wall absorbs the stain and they don't have an outer wall
• Gram positive bacteria structure

  • plasma membrane
  • thick cell wall
• Antibiotic resistance

  • gram negative bacteria are more resistant to antibiotics than gram positive bacteria
  • this is due to gram negative bacteria have a cell wall with an outer membrane, which protects them from antibiotics