Cell 1

• Cell


  The fundamental structural and functional unit of all living organisms
• Types of organisms


  • Unicellular organisms (e.g. Amoeba, Diatoms)
  • Multicellular organisms (e.g. plants, animals)
• Unicellular organisms


  • Capable of independent existence
  • Performing the essential functions of life
• Anything less than a complete structure of a cell does not ensure independent living
• Cell theory


  1. All living things are composed of cells and their products
  2. Cells are formed from pre-existing cells
  3. The activities of an organism are the outcome of the sum of acts and actions of its constituent cells
• Unicellular organisms


  • Amoeba
  • Diatoms
• Eukaryotic cells


  Cells that have a membrane-bound nucleus
• Prokaryotic cells


  Cells that lack a membrane-bound nucleus
• Prokaryotic cells


  • Lack membrane-bound organelles
  • Have a single circular chromosome as genetic material
  • May have additional plasmids
• Cell envelope


  The outer covering of a prokaryotic cell, consisting of the cell wall, cell membrane, and glycocalyx
• Cell wall


  • Provides additional strength and structural support to the prokaryotic cell
• Plasma membrane


  Selectively permeable membrane that interacts with the outside world
• Mesosome


  • Membranous extensions of the plasma membrane that help in cell wall formation, DNA replication, respiration, and secretion
• Flagella


  • Thin filamentous extensions from the cell wall that provide motility to some prokaryotic cells
• Pili and fimbriae


  Surface structures of bacteria that help in attachment and mating
• Ribosomes


  Non-membrane bound organelles that are the site of protein synthesis
• Inclusion bodies


  Membrane-bound or non-membrane bound structures in the cytoplasm that store reserve materials
• Cytoplasm is the main arena of cellular activities in both plant and animal cells
• Prokaryotic cells lack membrane-bound organelles
• The cell wall in prokaryotic cells provides additional strength and structural support