Edexcel A (SNAB) A Level Biology:复习笔记3.1.3 Prokaryotic Cells

• Animal and plant cells are types of eukaryotic cells, whereas bacteria are a type of prokaryote
• Prokaryotic cells are much smaller than eukaryotic cells
• They also differ from eukaryotic cells in having
  • A cytoplasm that lacks membrane-bound organelles
  • Ribosomes that are smaller (70 S) than those found in eukaryotic cells (80 S)
  • No nucleus, instead having a single circular bacterial chromosome that is free in the cytoplasm and is not associated with proteins
  • A cell wall that contains the glycoprotein murein
    • Murein is sometimes known as peptidoglycan
• In addition, many prokaryotic cells also have the following structures
  • Loops of DNA known as plasmids
  • Capsules
  • Flagella (singular flagellum)
  • Pili (singular pilus)
  • A cell membrane that contains folds known as mesosomes

Additional Prokaryotic Structures Table

Bacteria are prokaryotic cells

Prokaryotes vs eukaryotes

• There are a number of important structural and physiological differences between prokaryotic and eukaryotic cells
• These differences affect their metabolic processes and how they reproduce

Comparison of Prokaryotic and Eukaryotic Cells Table