Lesson 2

• Cytology


  Study of cells
• Cell


  Basic unit of life
• Robert Hooke


  • 1665 English Scientist
  • Used a microscope to examine cork (plant)
  • Hooke called what he saw "Cells"
• Anton Van Leeuwenhoek


  • 1674- discoveries concerning protozoa, RBC, capillary systems, and the life cycles of insects
• Robert Brown


  • Discovered the nucleus in 1833
• Dujardin


  • 1835- discovered that cells were not empty but filled with thick, jelly like fluid
• Matthias Schleiden


  • 1838- ALL PLANTS "ARE COMPOSED OF CELLS"
• Theodore Schwann


  • Also in 1838, discovered that ANIMALS WERE MADE OF CELL
• Rudolf Virchow


  • 1855, German Physician
  • "CELLS ONLY COME FROM OTHER CELLS"
  • Debunked "Theory of Spontaneous Generation"
• Cell Theory


  The combined work of Schleiden, Schwann, and Virchow
• Cell Theory


  • All living things are composed of a cell or cells
  • Cells are the basic unit of life
  • All cells come from preexisting cells
• Prokaryotic


  • Do not have structures surrounded by membranes
  • Few internal structures
  • One-celled organisms, Bacteria
• Eukaryotic


  • Contain organelles surrounded by membranes
  • Most living organisms
• Cell Membrane


  • Outer membrane of cell that controls movement in and out of the cell
  • Double layer
• Cell Membrane


  • The lipid bilayer forms from amphipathic phospholipids, stabilized by cholesterol, and contains many embedded (integral) proteins and many peripheral proteins on its cytoplasmic surface
  • Endocytosis is cellular uptake of macromolecules or fluid by plasma membrane engulfment or invagination, followed by the "pinching off" of a filled membranous vesicle in the cytoplasm
  • Major types of endocytosis include Phagocytosis, Pinocytosis, Receptor-mediated endocytosis
  • Exocytosis: cytoplasmic membrane vesicles fuse with the plasma membrane and release their contents to the extracellular space
• Cell Wall


  • Most commonly found in plant cells & bacteria
  • Supports & protects cells
• Nucleus


  • Directs cell activities
  • Separated from cytoplasm by nuclear membrane
  • Contains genetic material - DNA
• Nuclear Membrane


  • Surrounds nucleus
  • Made of two layers
  • Openings allow material to enter and leave nucleus
• Chromosomes


  • In nucleus
  • Made of DNA
  • Contain instructions for traits & characteristics
• Nucleolus


  • Inside nucleus
  • Contains RNA to build proteins
• Cytoplasm


  • Gel-like mixture
  • Surrounded by cell membrane
  • Contains hereditary material
• Endoplasmic Reticulum


  • Moves materials around in cell
  • Smooth type: lacks ribosomes
  • Rough type: ribosomes embedded in surface
• Ribosomes


  • Make proteins
  • Found on ribosomes & floating throughout the cell
• Mitochondria


  • Produces energy through chemical reactions – breaking down fats & carbohydrates
  • Controls level of water and other materials in cell
  • Recycles and decomposes proteins, fats, and carbohydrates
• Golgi Bodies


  • Protein 'packaging plant'
  • Move materials within the cell
  • Move materials out of the cell
• Lysosomes


  • Digestive 'plant' for proteins, fats, and carbohydrates
  • Transports undigested material to cell membrane for removal
  • Cell breaks down if lysosome explodes
• Mitosis


  1. Cell copies its DNA

  2. Copies are separated & sorted into two sides of the cell

  3. Cell splits in two

  4. Part of each parent is carried to the two new cells
• Mitosis


  Results in cells such as internal organs, skin, bones, blood, etc.
• Meiosis


  1. Cell copies its DNA (part of a chromosome)

  2. Results in reproductive cells (sperm, eggs, etc)

  3. Part of each parent is carried to the four new cells
• Meiosis


  Evolved to solve the problem of organisms mating and combining their genes together (creating genetic diversity)
• Mitosis


  Makes the cell two (diploid)
• Meiosis


  Results in egg and sperm (haploid)
• Vocabulary


  • Diploid
  • Haploid
  • Interphase
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis
• Interphase


  DNA is replicated along with organelles and other cellular components and the cell prepares for division
• Prophase


  The DNA recoils, and the chromosomes condense; the nuclear membrane disappears, and the mitotic spindles begin to form
• Metaphase


  The chromosomes line up the middle of the cell with the help of spindle fibers attached to the centromere of each replicated chromosome
• Anaphase


  The chromosomes split in the middle and the sister chromatids are pulled by the spindle fibers to opposite poles of the cell
• Telophase


  The chromosomes, along with the cytoplasm and its organelles and membranes are divided into 2 portions
• Cytokinesis


  The actual splitting of the daughter cells into two separate cells
• Meiosis Interphase


  The chromosomes have replicated, and the chromatin begins to condense