Prokaryotic cells and Viruses

• What is the cell wall in prokaryotes made up of?

  Made of polymer called murein. Murein is a glycoprotien.
• What is glycoprotein?

  A protein with a carbohydrate attached
• What is the flagellum?

  Long hair like structure that rotates to make the prokaryotic cell move.
• Where does the DNA stay in a prokaryotic cell?

  The DNA floats free in the cytoplasm
• How does the DNA look in a prokaryotic cell?

  Circular DNA present as one long coiled up strand. Its not attached to any histones proteins.
• What are plasmids?

  Small loops of DNA that aren't part of the main circular DNA molecule .
• What do plasmids contain?

  Contains genes for things like antibiotic resistance, and can be passed between prokaryotes.
• Why do some prokaryotes have a capsule made of secreted slime?

  Helps to protect the bacteria from attack by cells of the immune system.
• How big are prokaryotic cells?

  Less than 2 μm in diameter
• What is the process called where prokaryotic cells replicate?

  Binary Fusion
• What happens in binary fusion?

  Cell replicates its genetic material, before physically splitting into two daughter cells.
• The process of binary fusion

  1. The circular DNA and plasmids replicate. Main DNA loop is only replicated once, but plasmids can be replicated loads of times.
  2. Cell gets bigger and DNA loops move to opposite ends of the cell
  3. Cytoplasm begins to divide and new cell walls begin to form
  4. Cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of circular DNA, but can have loads of copies of plasmids
• What are viruses?

  Viruses are acellular and are just nucleic acids surrounded by proteins
• How do viruses increase?

  They invade and reproduce inside the cells of other organisms . These cells known as host cells.
• Basic structures of viruses

  • Core of genetic material - either DNA or RNA
  • Protein coat called a Capsid, with attachment proteins sticking out from it. Attachment proteins let virus cling onto a suitable host cell
• How do viruses replicate?

  They inject their DNA or RNA into host cells - the hijacked cell then uses its own machinery ( enzymes or ribosomes) to the replicate the viral particles
• Steps of virus replication

  First attach to the host cell surface - to do this they use attachment proteins to bind to the complementary receptor proteins on the cell-surface membrane of the host cell. Different viruses have different attachment proteins and therefore require different receptor proteins on host cells.