Prokaryotes

• What are prokaryotic cells?


  Single-celled organisms that lack a nucleus and membrane-bound organelles
• What are the characteristics of prokaryotic cells?


  • Lack a nuclear membrane
  • Absence of mitochondria, Golgi bodies, chloroplasts, and lysosomes
  • Genetic material on a single chromosome
  • Lack histone proteins
  • Cell wall made of carbohydrates and amino acids
  • Plasma membrane acts as mitochondrial membrane
  • Divide asexually by binary fission and sexually by conjugation
• Why do prokaryotic cells lack histone proteins?


  Histone proteins bind to DNA and help control gene activity
• What is the function of the capsule in prokaryotic cells?


  It helps in moisture retention and protects the cell
• What is the primary composition of the cell wall in eubacteria?


  It is primarily composed of peptidoglycan
• What is the role of ribosomes in prokaryotic cells?


  They are involved in protein synthesis
• What are the three basic shapes of prokaryotic cells?


  1. Cocci (Round)
  2. Bacilli (Rod)
  3. Helical (Spiral)

  
• What does a Gram stain indicate about bacteria?


  It identifies bacteria as either gram positive or gram negative
• What color do gram positive bacteria stain?


  Blue
• Why are gram negative bacteria harder to treat with antibiotics?


  They have a thin peptidoglycan layer
• What are the two modes of prokaryotic reproduction?


  • Asexual reproduction through binary fission
  • Sexual reproduction through recombination
• What are the steps of binary fission in prokaryotic cells?


  1. DNA replicates and attaches to the cell membrane
  2. Cell wall increases in size and moves inward
  3. A cell wall forms between each DNA, dividing the cell into two daughter cells
• What are the three ways recombination can occur in prokaryotic cells?


  1. Conjugation: Gene transfer through a pilus
  2. Transformation: Uptake of DNA from the surroundings
  3. Transduction: Transfer of genetic material via viruses
• What is the composition of the cell wall in bacterial cells?

  Peptidoglycan
• What is the function of plasmids in bacterial cells?


  They are extrachromosomal DNA structures that can replicate independently
• What is the ability of bacteria to form endospores?


  It helps them survive under unfavorable conditions
• What are the characteristics of archaeal cells?


  • Found in extreme environments
  • Have a cell wall and flagella
  • Cell wall does not contain peptidoglycan
  • Membranes have different lipids
  • Possess one circular chromosome and plasmids