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7-1 Life is Cellular

7-1 Life is Cellular

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7-1 Life is Cellular

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  1. 7-1 Life is Cellular The cell is the common structure that makes up every living thing

  2. The discovery of the cell • Without the instruments to make them visible, cells remained unknown for most of human history.

  3. Early MIcroscopes • In 1665, Englishman Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material. • Under the microscope, cork seemed to be made of thousands of tiny, empty chambers. • He called these chambers “cells” bacause they reminded him of a monastary’s tiny rooms, which were called cells.

  4. Early microscopes

  5. Early Microscopes

  6. Early Microscopes

  7. Early Microscopes

  8. Early Microscopes • In Holland around the same time, Anton van Leeuwehoek used a single-lens microscope to observe pond water and other things

  9. Early Microscopes

  10. Early Microscopes

  11. The Cell Theory • Numerous observations soon made it clear that cells are the basic units of life • 1838-Matthias Schlieden concluded that all plants were made of cells • 1839-Theodor Schwann states that all animals were made of cells

  12. The Cell Theory • The cell theory states: • All living things are composed of cells • Cells are the basic units of structure and function in living things • New cells are produced from existing cells

  13. Exploring the Cell • Light itself limits the detail, or resolution, of images that can be made with the light microscope. • Light waves are diffracted, or scattered, as they pass through matter making it impossible to visualize tiny structures such as proteins and viruses with a light microscope

  14. Exploring the Cell

  15. Exploring the Cell

  16. Electron Microscopes • Electron microscopes are capable of revealing details as much as 1000 times smaller than those visible in light microscopes. • Transmission electron microscopes (TEMs) make it possible to explore tiny structures, but specimens must be cut into ultrathin slices • Scanning electron microscopes (SEMs) scan a beam of electrons over the surface of the specimen, specimens do mot have to be sliced

  17. Electron Microscopes

  18. Electron Microscopes

  19. Electron Microscopes

  20. Electron Microscopes

  21. Scanning Probe Microscopes • These have made it possible to observe single atoms • DNA and proteins have also been made visible by these

  22. Prokaryotes and Eukaryotes • All cells have 2 things in common: they are surrounded by a thick barrier called a cell membrane, and they contain DNA • The nucleus is a large membrane enclosed structure that contains the cell’s DNA • Eukaryotes are cells that contain nuclei • Prokaryotes are cells that do not contain nuclei

  23. Prokaryotes and Eukaryotes

  24. prokaryotes • Prokaryotic cells are generally smaller and simpler than eukaryotic cells. • Prokaryotic cells have genetic material not contained in a nucleus

  25. prokaryotes

  26. eukaryotes • Eukaryotes are generally larger and more complex than prokaryotic cells. The nucleus separates their genetic material from the rest of the cell

  27. eukaryotes