Binary Fission

• Binary fission involves:

  1. Replication of DNA and plasmids followed by...
  2. Division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of plasmids.
• 1. Replication of circular DNA and plasmids.
  2. Cell gets bigger and loops move to opposite poles.
  3. Cytoplasm begins dividing
  4. Two daughter cells produced
• Step 1:

  The circular DNA (nucleoid) and plasmid(s) replicate. The main DNA loop is only replicated once, but plasmids can be replicated loads of times.
• Step 2:

  The cell gets bigger and the DNA loops move to opposite 'poles' (ends) of the cell.
• Step 3:

  The cytoplasm begins to divide and the new peptidoglycan cell wall begins to form.
• Step 4:

  The cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmid(s).
• Antibiotics work in a number of different ways. One is preventing bacteria from making normal cell walls. Penicillin works by inhibiting certain enzymes required for the synthesis and assembly of the peptide cross linkages (chemical bonds) in bacterial cell walls. This weakens the walls, making them unable to withstand pressure.  As water enters by osmosis, the cell then bursts and the bacterium dies.  
• Antibiotics only work on bacteria- not viruses.