Cell Theory- Biology

• Robert Hook using a microscope first observed and named cells in a piece or cork


  1665
• Robert Brown was the first to observe the nucleus of a cell


  1833
• Schleiden and Schwann developed the theory that all living things are made of cells and that cells are the basic building blocks of life


  1839
• Prokaryotic cells


  The simplest and most ancient cells
• Eukaryotic cells


  Thought to have evolved from prokaryotic cells
• Similarities between prokaryotes and eukaryotes

  • Have DNA as their genetic material
  • Have ribosomes
  • Have cytoplasm
  • Have a plasma membrane
• Prokaryotes


  • Do not have a nucleus or membrane bound organelles
• Eukaryotic cells


  • Contain a nucleus and membrane bound organelles
• Prokaryotes


  Single celled organisms
• Eukaryotes


  Can be either single celled or multicelled
• DNA of a prokaryote


  Usually organized as a single circular chromosome
• DNA of a eukaryotic cell

  Organized as linear chromosomes
• Nucleus


  Storage site for most of the cell's genetic information
• Nucleolus


  Inside the nucleus, where the components of ribosomes are manufactured
• Endomembrane system


  A collection of membrane bound organelles consisting of the nuclear envelope, the rough and smooth endoplasmic reticulum, the Golgi apparatus, and several types of vesicles
• Endoplasmic reticulum (ER)


  A membranous network of sack like structures
• Rough ER


  Appears rough because of the presence of ribosomes on its surface, location of protein synthesis in the cell
• Smooth ER


  Has no ribosomes, involved in lipid synthesis, detoxification and carbohydrate metabolism
• Golgi apparatus


  Consists of a series of flattened sacks that resemble pancakes, packages and distributes cellular products
• Lysosomes


  Membrane bound vesicles that contain hydrolytic enzymes and aid in the breakdown of materials within the cell
• Mitochondria


  Found in both plant and animal cells, produce cellular energy in the form of ATP
• Chloroplasts


  The site of photosynthesis, only found in plant cells
• Vacuoles


  Found mainly in plant cells, store pigments, water, sugar, salts, and toxic molecules
• Cytoskeleton


  A network of hollow protein fibers that provides structural support, movement of organelles within the cell, form cilia and flagella, and provide the framework for moving and separating chromosomes during cell division
• Endocytosis


  1. Mechanism used by eukaryotic cells to ingest food particles in which the plasma membrane surrounds and engulfs a food particle

  2. Types: phagocytosis (solids), pinocytosis (liquids), receptor-mediated endocytosis (low density lipoproteins)
• Exocytosis


  Results in the discharge of materials in membrane bound packages that migrate to the inner surface of the plasma membrane, fuse with the membrane, and then release their contents to the outside of the cell
• Endosymbionts


  Microorganisms that live within other cells and perform specific functions for their host cells
• Theory of endosymbiosis


  • Proposes that eukaryotic cells had endosymbiotic relationships with prokaryotes
  • Photosynthetic bacteria living within eukaryotic cells evolved into chloroplasts
  • Energy producing bacteria living within larger cells evolved into mitochondria