Prokaryotic cells and viruses

• What causes a muscle cell to differ from a skin cell despite having the same genes?

  The muscle cell expresses different genes from the skin cell
• Why can't antibiotics be used against viruses?

  Because viruses are not living cells
• What is the size range of viruses?

  20-300 nm
• What is a characteristic feature of prokaryotic cells?

  They have no membrane-bound organelles
• What is the genetic material in prokaryotic cells like?

  It is circular DNA, free in the cytoplasm
• What is the function of the capsule in prokaryotic cells?

  It provides protection
• What type of ribosomes are found in prokaryotic cells?

  70S ribosomes
• How do prokaryotic cells divide?

  By binary fission
• What are the key differences between prokaryotic and eukaryotic cells?

  • Prokaryotic cells lack a nucleus; eukaryotic cells have a nucleus
  • Prokaryotic cells have circular DNA; eukaryotic cells have linear DNA
  • Prokaryotic cells have 70S ribosomes; eukaryotic cells have 80S ribosomes
  • Prokaryotic cells lack membrane-bound organelles; eukaryotic cells have them
• What is the role of attachment proteins in viruses?

  They allow identification and attachment to host cells
• Why are viruses considered acellular?

  Because they are not made up of cells
• How do viruses replicate?

  By hijacking the host cell's replication processes
• What is a plasmid?

  Small loops of DNA that aren’t part of the main circular DNA molecule
• What is a flagellum?

  A long hair-like structure that rotates to make the prokaryotic cell move
• What are the features compared between prokaryotic and eukaryotic cells?

  • Nuclear envelope: Absent in prokaryotic, present in eukaryotic
  • Cell wall: Present in prokaryotic, sometimes in eukaryotic
  • Flagellum: Sometimes present in both
  • Ribosomes: Present in both
  • Plasmid: Sometimes present in prokaryotic, absent in eukaryotic
  • Cell surface membrane: Present in both
  • Mitochondria: Absent in prokaryotic, present in eukaryotic