cell division

• Chromosomes contain genetic information in the form of DNA
• Chromosomes


  Coiled up lengths of DNA molecules, each carrying many genes
• Body cells normally have two copies of each chromosome, one from each parent
• The cell cycle


  1. Growth and DNA replication

  2. Mitosis
• Mitosis


  The stage of the cell cycle when the cell divides, producing two genetically identical daughter cells
• Binary fission in prokaryotic cells

  1. DNA and plasmids replicate

  2. Cell gets bigger, DNA strands move to opposite ends

  3. Cytoplasm divides, forming two daughter cells
• Bacteria can divide very quickly, some like E. coli in as little as 20 minutes
• Cell division


  1. Cytoplasm and cell membrane divide

  2. Cell produces two new daughter cells

  3. Daughter cells contain identical DNA to parent cell
• Binary fission


  A type of simple cell division in prokaryotic cells
• Binary fission


  1. Circular DNA and plasmids replicate

  2. Cell gets bigger and DNA strands move to opposite poles

  3. Cytoplasm begins to divide and new cell walls form

  4. Cytoplasm divides and two daughter cells are produced, each with one copy of circular DNA
• Bacteria can divide very quickly if given the right conditions
• Some bacteria, such as E. coli, can take as little as 20 minutes to replicate in the right environment
• If conditions become unfavourable, bacterial cells will stop dividing and eventually begin to die
• Mean division time


  The average amount of time it takes for one bacterial cell to divide into two
• Using mean division time to find number of bacteria in a population

  1. Ensure time units are the same

  2. Divide total time by mean division time to get number of divisions

  3. Multiply 2 by itself for the number of divisions to find number of cells
• Each cell divides to produce 2 cells, so the number of cells increases by a power of 2 for each division