Bacterial Division (triple)

• Bacteria are prokaryotes, their genetic information is not enclosed in a nucleus
• Binary fission


  The process where one bacterial cell splits into two bacterial cells
• Bacteria can carry out binary fission once every 20 minutes as long as they have enough nutrients and the temperature is suitable
• Calculating the number of bacteria after a given time

  1. Calculate the number of rounds of division

  2. Use the equation: Number of bacteria = 2^n, where n is the number of rounds of division
• Sample question


  • Under ideal conditions, the type of bacterium divides every 20 minutes. Calculate the number of bacteria present after three hours.
• The equation Number of bacteria = 2^n, where n is the number of rounds of division, is not given in the exam so it's important to learn it
• To calculate the number of rounds of division, divide the total time by the division time (20 minutes)
• After three hours (180 minutes), the bacteria have undergone 9 rounds of division
• The number of bacteria after three hours is 512 (2^9)
• Standard form


  Expressing a number as a value between 1 and 10 multiplied by a power of 10
• Sample question


  • Under ideal conditions, a type of bacterium divides every 20 minutes. Calculate the number of bacteria present after eight hours.
• Eight hours is 480 minutes, so the bacteria have undergone 24 rounds of division
• The number of bacteria after eight hours is 16,777,216 (2^24)
• Expressed in standard form, the number of bacteria is 1.678 x 10^7