Upload
shaine-burris
View
117
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Cells and the Origin of Cell Theory. History of the Cell Theory. Before microscopes, belief in supernatural causes of diseases Could not see microorganisms What branch of biology? Cells = basic units of living organisms. Microscopes. Originally a hand lens to view quality of cloth - PowerPoint PPT Presentation
Citation preview
Cells and the Origin of Cell Theory
History of the Cell Theory
• Before microscopes, belief in supernatural causes of diseases
• Could not see microorganisms
• What branch of biology?
• Cells = basic units of living organisms
Microscopes
• Originally a hand lens to view quality of cloth
• Anton van Leeuwenhoek (mid-1600s) first to examine water under microscope
• Credited with development of light microscope
Anton von Leeuwenhoek’s Microscope
Improvements• Compound light
microscope- series of lens to magnify objects (1500x)
• Robert Hooke used one to observe cork magnified 30x
• Observed small geometric shapes
• Dubbed these cells (resembled monk rooms)
Hooke’s Microscope
Cell Theory
• 1830’s German scientist Matthias Schleiden realized that plants made up of cells
• Theodore Schwann made same determination of animals
• = Cell Theory
• Many resources (including your book) give only credit to Scleiden and Schwann
• Original third tenet was spontaneous generation
• Rudolph Virchow - "Omnis cellula e cellula”
Cell Theory
• All organisms are composed of one or more cells
• The cell is the basic unit of organization of organisms
• All cells come from preexisting cells
Recent Developments• 1940’s were able to use
beam of electrons instead of light
• 500 000x• Electron microscope• Scanning Electron
Microscope • Transmission Electron
Microscope
Scanning Electron Microscope
• SEM
• Electrons are reflected off the surface of the specimen
• 3D shape
• http://micro.magnet.fsu.edu/primer/virtual/virtual.html
• http://www.mos.org/sln/SEM/gallery.html
Transmission Electron Microscope
• TEM
• Allows to see inside of cell
• Electrons pass through instead of light
• http://nobelprize.org/physics/educational/microscopes/tem/
Size Comparison
Prokaryote vs. Eukaryote
• With the invention of microscopes, scientists could see two groups of cells
• Prokaryotes
• Eukaryotes
Prokaryote
• 1-10 m in diameter
• NO membrane-bound organelles
• 1 circular DNA molecule located in nucleoid region
• Plasma membrane, cytoplasm & ribosomes
• Most have a cell wall (peptidoglycan)
• May have a polysaccharide capsule
–Ex. bacteria & cyanobacteria
Prokaryotic Cell
Eukaryote• 10-100 m in diameter • Nucleus & other membrane-
bound organelles• 2 or more linear DNA
molecules located in nucleus• Plasma membrane,
cytoplasm & ribosomes some have a cell wall (cellulose or chitin)
Ex. plants, animals, fungi, protista
Animal Cell
Animal Cell
Plant Cell
QUESTIONS?????