biology paper 1

• Organisms can be Prokaryotes or Eukaryotes
• Eukaryotic cells are made up of cell organelles
• Prokaryotic cells are single-celled organisms
• Plant and Animal Cells

  • Have similarities and Differences
• Cell parts


  Are called organelles
• Animal cells have more organelles than plant cells
• Cell organelles are where most of the cell's activities happen
• Cell wall gives shape and support to the cell
• Cell membrane controls what goes in and out of the cell
• Chloroplasts are where photosynthesis happens in plant cells
• Bacterial cells are much smaller than eukaryotic cells
• Bacterial cells


  • Have a cell membrane
  • Have ribosomes
  • May have plasmids
• Bacterial cells do not have a true nucleus
• Bacterial DNA floats freely in the cytoplasm
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• Binary Fission


  1. Prokaryotic cells can reproduce using type of simple cell division called binary fission

  2. The circuler DNA and pleamid(s) aplicate

  3. The cell gets bigger and the souler DNA strands move to opposite "bols (eds) of the cell

  4. The cytoplasm begins to dhids and new call walls begin to form

  5. The cytoplasm divides and two daughter calls are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmids
• Bacteria can divide very quickly if given the sight conditions (ganiment and lots of cutrients). Some bacteria, such as E. coll, can take a little as 20 mhutes to replicate in the right environment. However, if conditions become unfasurable, the cells will stop dhiding and eventually begin to de
• Use Mean Division Time to Find the Number of Bacteria in a Population


  1. The mean division time is just the average amount of time it takes for one bacterial cell to divide into two

  2. If you know the mean division time of a cell, you can work out how many times it has divided in a certain amount of time, and so the number of cells it has produced in that time
• A bacterial cell has a mean division time of 30 minutes

  • How many cells will it have produced after 2.5 hours?
• Fission is division, there's no splitting hairs there...
• Each call divides to produce 2 cel so the number of cells increases by a power of 2 for each division
• Binary fission is the sort of subject where standard form could show up. Head back to p. 12 if you're unsure.
• Binary fission


  • Things that help to maximise the rate of binary fission
• E coll is a type of bacteria. The mean division time of an E coll cell is 20 minutes


  • How many cells will a single E. coli cell produce in 2 hours and 40 minutes
• Bacteria (and some other microorganisma) are grown (cultured) in a "culture medium".
• Culture medium


  • Carbohydrates
  • Minerals
  • Proteins
  • Vitamins
• Culture medium


  Can be nutrient heath solution or solid gjell
• Bacteris grown on ager 'plates' will form visible colonies on the surface of the jelly.