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So, What IS a Cell?

So, What IS a Cell?. A cell is the basic unit of structure and function in all living things. It needs water and nutrients to survive. It is found in all living things: bacteria, plants , and animals . It is NOT found in non-living things. Which ones would have cells?.

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So, What IS a Cell?

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  1. So, What IS a Cell? • A cell is the basic unit of structure and function in all living things. • It needs water and nutrients to survive. • It is found in all living things: bacteria, plants, and animals. • It is NOT found in non-living things.

  2. Which ones would have cells?

  3. Which ones would have cells?

  4. How Cells Were Discovered… 1665 Robert Hooke: Looked at a slice of cork through a microscope and discovered tiny boxes which he called “cells.”

  5. How Cells Were Discovered… 1673 Anton von Leeuwenhoek: looked at pond scum through a microscope and discovered single-celled organisms called protists.

  6. How Cells Were Discovered… 1838 Matthias Schleiden: studied plants and concluded that allplant parts were made of cells.

  7. How Cells Were Discovered… 1839 Theodor Schwann: studied animals and concluded that all animaltissues are made of cells.

  8. How Cells Were Discovered… 1858 Rudolf Virchow: discovered that cells could only come from other cells.

  9. ABC’s of the “Cell Theory” With all these discoveries, Schwann and Virchow came up with the cell theory: • All organisms are made of cells • The cell is the Basic unit of all living things • All cells Come from existing cells

  10. How Big are Cells? • Most cells are so tiny that you have to use a microscope to see them.

  11. Why are cells so tiny? • Because of the surface area-to-volume ratio: • Cells take in nutrients and get rid of wastes through their outside surface. • BUT the volume (space inside) grows faster than the surfacearea (the cell’s surface).

  12. Why are cells so tiny? • If the volume becomes too big, the cell cannot survive because…. • it can’t get enough nutrients in & • can’t get rid of wastes fast enough. Therefore, a cell only grows to a certain size.

  13. Balloon Analogy for Cell Size • If you blow into a balloon, the volume increases. • Eventually, the balloon’s surface • cannot stretch anymore. • When this happens, the balloon • cannot continue to exist and will pop. • Likewise, if a cell’s volume increases too much, the cell’s surface will not be able to get nutrients in or wastes out fast enough and it will die.

  14. A few cells are big • Some cells are big because they don’t need to take in nutrients or get rid of wastes. • Ie. Chicken egg is a cell

  15. Prokaryotes

  16. Eukaryotes

  17. Eukaryotic Cell (Eukaryotes) Prokaryotic Cell (Prokaryote) • Have a nucleus • Examples:plants, animals, and humans • Largest cells (10x larger than bacteria cells!) • DNA in nucleus • Many organelles • Most eukaryotes are multi-cellular (made of more than 1 cell) • No nucleus • 2 types: bacteria & • archebacteria • Smallestcells • Organelles: • DNA & ribosomes • only • Use flagellum (tail) • to move • Most prokaryotes are • Unicellular (only 1 cell) • *DNA • ribosomes, * cell membranes • cytoplasm

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