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Published byGraham Herbertson Modified over 9 years ago
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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.
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Which ones would have cells?
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Which ones would have cells?
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How Cells Were Discovered…
1665 Robert Hooke: Looked at a slice of cork through a microscope and discovered tiny boxes which he called “cells.”
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How Cells Were Discovered…
1673 Anton von Leeuwenhoek: looked at pond scum through a microscope and discovered single-celled organisms called protists. Amoeba, an example of a protist
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How Cells Were Discovered…
1838 Matthias Schleiden: studied plants and concluded that all plant parts were made of cells. Tomatoes:
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How Cells Were Discovered…
1839 Theodor Schwann: studied animals and concluded that all animal tissues are made of cells. Pueblan Milk snake Clown fish Grizzly bear
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How Cells Were Discovered…
1858 Rudolf Virchow: discovered that cells could only come from other cells.
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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 1 & 2: building block/legos 3. Just like all animals must come from another animal, or plants come from the seeds of another plant; we don’t just come from rocks or thin air.
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How Big are Cells? Most cells are so tiny that you have to use a microscope to see them. 1 & 2: building block/legos 3. Just like all animals must come from another animal, or plants come from the seeds of another plant; we don’t just come from rocks or thin air.
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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 surface area (the cell’s surface). 1 & 2: building block/legos 3. Just like all animals must come from another animal, or plants come from the seeds of another plant; we don’t just come from rocks or thin air.
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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. 1 & 2: building block/legos 3. Just like all animals must come from another animal, or plants come from the seeds of another plant; we don’t just come from rocks or thin air.
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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.
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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 1 & 2: building block/legos 3. Just like all animals must come from another animal, or plants come from the seeds of another plant; we don’t just come from rocks or thin air.
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Prokaryotes 1 & 2: building block/legos
3. Just like all animals must come from another animal, or plants come from the seeds of another plant; we don’t just come from rocks or thin air.
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Eukaryotes 1 & 2: building block/legos
3. Just like all animals must come from another animal, or plants come from the seeds of another plant; we don’t just come from rocks or thin air.
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Prokaryotic Cell (Prokaryote)
Eukaryotic Cell (Eukaryotes) No nucleus 2 types: bacteria & archebacteria Smallest cells Organelles: DNA & ribosomes only Use flagellum (tail) to move Most prokaryotes are Unicellular (only 1 cell) 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) *DNA ribosomes, * cell membranes cytoplasm
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