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The Characteristics of a Cell (4.1)

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  1. 1. The Characteristics of a Cell Chapter 4 Section 1
  2. 2. Key Concept <ul><li>Cells function similarly in all living organisms </li></ul>                               
  3. 3. So What’s a Cell? <ul><li>Would you believe that a chicken egg or ostrich egg is a cell?  </li></ul><ul><li>Look at the relative sizes of these cells (human cell is actually much smaller) </li></ul><ul><li>Most cells are so small they could only be seen with a microscope </li></ul>
  4. 4. Cells <ul><li>A cell is the simplest living thing that can have a &quot;life of its own.&quot; </li></ul><ul><li>Cells were only discovered after the invention of the microscope in the mid-1600s </li></ul>
  5. 5. Scientists and Cells <ul><li>Robert Hooke – 1665 built a microscope to look at tiny objects </li></ul><ul><li>Saw cork (bark of cork tree) made of “little boxes” (cells) </li></ul><ul><li>He also looked at plants, feathers, fish scales, and housefly eyes </li></ul>
  6. 6. Scientists and Cells Cont… <ul><li>1673 – Anton van Leeuwenhoek saw small organisms in water (“animalcules”) </li></ul><ul><li>Actually was seeing single-celled protists </li></ul><ul><li>Also looked at blood of different kinds of animals: </li></ul><ul><ul><li>Fish, bird, frog blood cells were oval </li></ul></ul><ul><ul><li>Human and dog blood cells were round and flat </li></ul></ul><ul><li>First person to see bacteria </li></ul>
  7. 7. Contributors to the Cell Theory <ul><li>1838- Matthias Schleiden found that all plant parts were made of cells </li></ul><ul><li>1839 – Theodor Schwann found that all animal tissues were made of cells </li></ul><ul><li>1858 – Rudolf Virchow stated that all cells could only come from other cells </li></ul>
  8. 8. The Cell Theory <ul><li>All organisms are made up of one or more cells </li></ul><ul><li>The cell is the basic unit of all living things </li></ul><ul><li>All cells come from existing cells </li></ul>
  9. 9. Parts of a Cell <ul><li>Cells have different functions and come in different shapes and sizes </li></ul><ul><li>ALL cells have some parts in common: </li></ul><ul><ul><li>Cell membrane (barrier between cell & environment) </li></ul></ul><ul><ul><li>Cytoplasm (fluid inside) </li></ul></ul><ul><ul><li>Organelles (“mini organs”) </li></ul></ul><ul><ul><li>Genetic Material (DNA) </li></ul></ul>
  10. 10. Two Kinds of Cells <ul><li>Cells that have a nucleus are eukaryotic cells </li></ul><ul><li>Cells that do not have a nucleus are prokaryotic cells </li></ul>
  11. 11. Prokaryotes: Eukaryotes: <ul><li>Single celled </li></ul><ul><li>No nucleus </li></ul><ul><li>DNA </li></ul><ul><li>No membrane bound organelles </li></ul><ul><li>Ribosomes </li></ul><ul><li>Have strong cell walls </li></ul><ul><li>Bacteria, Archaea </li></ul><ul><li>Multicellular </li></ul><ul><li>Nucleus </li></ul><ul><li>DNA </li></ul><ul><li>Membrane bound organelles </li></ul><ul><li>Ribosomes </li></ul><ul><li>Some have cell walls </li></ul><ul><li>Plants, Animals, Fungi, Protozoa </li></ul>
  12. 12. Pop Quiz <ul><li>Question: Who was the first person to see bacteria? </li></ul><ul><li>Answer: Anton van Leewenhoek </li></ul><ul><li>Question: According to the cell theory, where do cells come from? </li></ul><ul><li>Answer: Other cells </li></ul><ul><li>Question: What parts do all cells have in common? </li></ul><ul><li>Answer: Cell membrane, cytoplasm, organelles, DNA </li></ul>

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