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7.1 Cell Discovery and Theory

7.1 Cell Discovery and Theory. JOURNAL. CELL. Think About It…. What’s the smallest part of any living thing that still counts as being alive?

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7.1 Cell Discovery and Theory

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  1. 7.1 Cell Discovery and Theory

  2. JOURNAL CELL

  3. Think About It… • What’s the smallest part of any living thing that still counts as being alive? • Is a leaf alive? How about your big toe? How about a drop of blood? Can we just keep dividing living things into smaller and smaller parts, or is there a point at which what’s left is no longer alive? As you will see, there is such a limit, the smallest living unit of any organism – the cell.

  4. HAND LENS DEMO

  5. Early Microscopes • 1500s – eyeglass makers in Europe discovered that using several glass lenses in combination could magnify even the smallest objects to make them easy to see.

  6. Robert Hooke He looks like this… maybe?.. • English Scientist • 1665- Used crude microscope to observe thin slices of cork. • Saw “little boxes” = little rooms = cells Was the 1st person to use this term!!

  7. Anton van Leeuwenhoek • Dutch scientist • 1675- Used microscope to view pond water. Called living creatures “animalcules” • 1st person to observe LIVING cells VIDEO

  8. Other Contributors “All plants are made of cells.” -Matthias Schleiden “All animals are made of cells.” -Theodor Schwann “New cells can be produced only from the division of existing cells.” -Rudolph Virchow

  9. The Cell Theory • All living things are made up of cells. • Cells are the basic units of structure and organization in living things. • New cells are produced from existing cells

  10. Journal • Choose one person who was influential in the discovery of cells and formation of the cell theory. Give their name and discuss their contribution (what they did that was worth putting in your textbook)

  11. Think About It… • Looking at the timeline, why do you think there often were long periods of time between significant discoveries about cells?

  12. How do microscopes work? • Most microscopes use lenses to magnify the image of an object by focusing light or electrons.

  13. Compound Light Microscopes • Used to view living cells • Utilizes a series of glass lenses and visible light to magnify an image • Magnifies images up to 1,000 times the actual size

  14. Transmission Electron (TEM) Views INTERNAL structure Scanning Electron (SEM) Views EXTERNAL structure Electron Microscopes • Utilizes magnets to aim a beam of electrons at a cell to produce an image • CANNOT be used to view living cells • Magnifies an image up to 500,000 times actual size

  15. Journal • You are presented with a specimen to examine. What are two questions you would ask to determine the best microscope to use?

  16. All Cells… • Are surrounded by a plasma membrane – special membrane that controls what enters and leaves the cell • Contain genetic material in some form that provides instructions for making substances that the cell needs • Break down molecules to obtain energy

  17. Prokaryotes & Eukaryotes • Prokaryotes - cells without a nucleus or other membrane-bound organelles; bacteria • Eukaryotes – contain a nucleus and other organelles that are bound by membranes

  18. JOURNAL • You identify a cell on a microscope, but aren’t sure what type of cell it is. What are 2 things that MUST be true of the cell?

  19. Journal • In your own words, explain the difference between prokaryotic and eukaryotic cells.

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