Prokaryotic Cells and Viruses

• • Just like in a eukaryotic cell the cell surface membrane is mainly made of lipids and proteins. It controls the movement of substances into and out of the cell
• Cytoplasm contains ribosomes - but they're smaller than those in a eukaryotic cell
• • The flagellum is a long, hair-like structure that rotates to make the cell move. Not all prokaryotes have a flagellum, some have more than one
• • Unlike a eukaryotic cell, a prokaryotic cell doesn't have a nucleus. Instead, the DNA floats free in the cytoplasm. Its circular DNA, present as one long coiled-up strand. Its not attached to any histone proteins
• • Plasmids are small loops of DNA that aren't part of the main circular DNA molecule. Plasmids contain genes for things like antibiotic resistance, and can be passed between prokaryotes. Plasmids are not always present in prokaryotic cells. Some prokaryotic cells have several
• • Some prokaryotes also have a capsule made up of secreted slime. It helps to protect the bacteria from attack by cells of the immune system
• The process of binary fission

  1. The circular DNA and plasmids replicate. The main DNA loop is only replicated once, but plasmids can be replicated loads of times
  2. The cell gets bigger and the DNA loops move to opposite poles
  3. The cytoplasm begins to divide and new cell walls begin to form
  4. The cytoplasm divides and two daughter cells are produced. Each daughter cell has on copy of the circular DNA but can have a variable number of copies of the plasmid