BIOLOGY

• Robert Hooke (1665):

  • English scientist who used an early compound microscope to look at thin slices of cork
  • First used the word "cell", referring to tiny, empty chambers that make up plant cork
• Anton van Leeuwenhoek:

  • Dutch scientist who used a single-lens microscope to view pond water and other things
  • Was a lens-maker
• Matthias Schleiden (1838):

  • German botanist who first concluded that all plants are made of cells
• Theodor Schwann (1839):

  • German biologist who first concluded that all animals are made up of cells
  • Said all living things are made of cells
• Rudolf Virchow (1855):

  • German physician who concluded that new cells only come from existing cells
• Cell theory states:

  • All living things are made of cells
  • Cells are the basic unit of structure and function in living things
  • New cells are produced from existing cells
• Techniques used to explore the cell closely:

  • Fluorescent labeling: follows molecules moving through a cell
  • Confocal light microscopy: scans cells with a laser beam to build 3-D images
  • High-resolution video technology: produces movies of cells as they grow, divide, and develop
• Types of Electron Microscopes:

  • TEMs (transmission electron microscopes) used to study cell structures and protein molecules
  • SEMs (scanning electron microscopes) scan surfaces of specimens and make 3-D images
  • Scanning probe microscopes: trace surfaces of samples with a fine probe, great for viewing single atoms
• All cells have 2 characteristics:

  • Have a cell membrane
  • Contain DNA
• Eukaryotic cells:

  • Contain a nucleus and many organelles (e.g., plant and animal cells)
  • Larger/complex cells that are highly specialized with parts having specific functions
  • Nucleus stores genetic material separately from the rest of the cell
  • Can be single or multicellular
• Prokaryotic cells:

  • Cells with no nucleus and few organelles (e.g., bacterial cells)
  • Usually smaller/simple and have genetic material not contained in a nucleus
• Discovery of Cells:

  • Robert Hooke (1600’s) discovered “little chambers” (cells) in cork plant
  • Anton van Leeuwenhoek (1600’s) used a microscope to view living things in pond water and saw things swimming around
• Matthias Schleiden (1838) concluded that plants are made of cells

  • Thoedor Schwann (1839) concluded that all animals are made of cells
• Cell Theory:

  1. All living things are made up of cells

  2. Cells are the smallest working units of all living things

  3. All cells come from preexisting cells through cell division
• Definition of Cell:

  • A cell is the smallest unit capable of performing life functions
• Examples of Cells:

  • Amoeba Proteus
  • Plant Stem
  • Red Blood Cell
  • Nerve Cell
  • Bacteria
• Two Types of Cells:

  Prokaryotic:

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

  Eukaryotic:

  • Contain organelles surrounded by membranes
  • Most living organisms
  • Plant
  • Animal
• “Typical” Animal Cell:

  • Contains organelles surrounded by membranes
• Eukaryotic Cell Parts:

  • Cell Membrane: outer membrane that controls movement in and out of the cell
  • Cell Wall: supports and protects cells, commonly found in plant cells, bacteria, and fungi
  • Nucleus: directs cell activities, contains genetic material (DNA)
  • Nuclear Membrane: surrounds the nucleus, made of two layers with openings for material to enter and leave
  • Chromatin: DNA in the form it takes most of the time, made of DNA wrapped up with proteins
  • Chromosomes: DNA wrapped up tight by proteins called “histones,” contain instructions for traits and characteristics
• • Nucleolus: inside the nucleus, contains RNA to build proteins
  • Cytoplasm: gel-like mixture surrounded by the cell membrane, contains hereditary material in prokaryotes
  • Ribosomes: make proteins, found on endoplasmic reticulum and floating in the cytoplasm
  • Endoplasmic Reticulum: moves materials around in the cell, smooth type lacks ribosomes, rough type has ribosomes embedded in the surface
  • Mitochondria: produces energy through chemical reactions, controls level of water and other materials, recycles and decomposes proteins, fats, and carbohydrates
• • Golgi Bodies: protein 'packaging plant,' moves materials within and out of the cell
  • Lysosome: digestive 'plant' for proteins, fats, and carbohydrates, transports undigested material for removal, cell breaks down if lysosome explodes
  • Vacuoles: membrane-bound sacs for storage, digestion, and waste removal, helps plants maintain shape
  • Chloroplast: usually found in plant cells, contains green chlorophyll, where photosynthesis takes place
  • Centrioles: used during animal cell division
• Prokaryotic Cells:

  • Ribosomes
  • DNA or RNA
  • Cytoplasm
• Cell Boundaries:

  • Cell Membrane: controls what goes in and out, provides support and protection
  • Cell Wall: provides support and protection
• Diffusion through Cell Boundaries:

  • Membrane controls movement of dissolved molecules in and out of the cell
• Concentration of Solutions:

  • The greater the ratio of solute to solvent, the higher the concentration
• Diffusion:

  • Movement of particles from an area of greater to lesser concentration
  • Requires no energy to move substances across a membrane
• Equilibrium:

  • When solute concentration is equal throughout the solution
• Osmosis:

  • The diffusion of water through a membrane
  • Water moves from an area of greater concentration to lesser concentration
• Concentration of Solutions:

  • Isotonic: concentration of particles is the same on both sides of the membrane
  • Hypertonic: stronger solution
  • Hypotonic: less concentrated solution
• How Osmosis Works in Cells:

  • Isotonic: cell maintains its shape
  • Hypertonic
• the cell