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Cell Theory and Structure

Learn about the history of cell discovery, the cell theory, differences between eukaryotes and prokaryotes, and the structure of cells including organelles like the nucleus, ribosomes, mitochondria, and more.

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Cell Theory and Structure

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  1. Cell Theory and Structure

  2. Discovery of the Cell • Scientists did not start using simple compound microscopes until the mid 1600’s. • Robert Hooke used an early compound microscope to look at slices of cork. • Hooke named the ‘seemingly empty’ chambers ‘cells.’ • Around the same time, Anton von Leeuwenhoek was using a single-lens microscope to observe unicellular organisms in pond water for the first time. http://www.smithlifescience.com/cork2.GIF

  3. Cell Theory • Additional observations of cells in other living things led scientists to 3 basic conclusions, known as the cell theory. • 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.

  4. Eukaryotes • Nucleus • Many organelles • Large in size • Ex: Humans, plants, fungi, etc. There are two categories of cells…… • Prokaryotes • No nucleus • Few organelles • Small in size • Ex: Bacteria http://www.cod.edu/people/faculty/fancher/EukaryoticCell.jpg http://www.cod.edu/people/faculty/fancher/ProkaryoticCell.jpg

  5. Cell Structure • All cells, both prokaryotes and eukaryotes, have DNA and a cell membrane. • Cells also contain organelles – specialized structures within the cell that perform certain tasks. • These organelles float around in the cell’s cytoplasm, which is mostly made of water.

  6. Prokaryotes…….they’re simple. • Prokaryotes only have a few basic structures: • DNA • Cell/plasma membrane • Cell wall • Ribosomes • Some use structures like pili, cilia, and flagellum to move in aquatic environments. http://scienceblogs.com/clock/2006/11/cell_structure.php

  7. ….but they come in many varieties. http://images.google.com/imgres?imgurl=http://www.harlem-school.com/10TH/sci_pdf/graphics/prokaryotic_entities.gif&imgrefurl=http://www.harlem-school.com/10TH/sci_pdf/sci.html&h=396&w=284&sz=32&hl=en&start=12&tbnid=dQsSJBBu88uFiM:&tbnh=124&tbnw=89&prev=/images%3Fq%3Ddifferent%2Bshaped,%2Bprokaryotic%26gbv%3D2%26svnum%3D10%26hl%3Den%26safe%3Dactive

  8. Eukaryotes are more complex. • Eukaryotes can be multicellular or unicellular. • Eukaryotes contain many organelles…….

  9. Do you know your Organelles?

  10. Cell (plasma) membrane • Regulates what materials enter and leave the cell.

  11. Nucleus • Controls most cell processes and contains nearly all of the cell’s DNA

  12. Ribosomes • assemble proteins. • Some are free floating while others are attached to the endoplasmic reticulum.

  13. Endoplasmic Reticulum (ER) • There are two types: • Rough – chemically modifies proteins that are produced by the ribosomes on its surface. • Smooth – contains specialized enzymes and makes lipid components for the cell membrane.

  14. Golgi apparatus • Sorts, modifies, and/or packages proteins and other materials from the ER for storage or secretion from the cell.

  15. Lysosomes and peroxisomes • Lysosomes contain enzymes that are specialized to digest lipids, carbs, proteins so their monomers can be reused • Peroxisomess contain enzymes that are specialized to digest toxic substances

  16. http://scienceblogs.com/clock/2006/11/cell_structure.php Cytoskeleton • A network of protein filaments (microtubules and microfilaments) that help the cell move and maintain its shape

  17. Mitochondria • Provides the cell with usable chemical energy • It is the site of cellular respiration.

  18. How are they different? http://staff.tuhsd.k12.az.us/gfoster/standard/BCELL1_files/image005.jpg http://scienceblogs.com/clock/2006/11/cell_structure.php

  19. Plant cells have special features….. • Plants contain: • Chloroplasts – create and store usable energy through the process of photosynthesis. • Cell wall – provides the cell with rigid structure. • 1 Large vacuole – used for the storage of water and some other materials • Animal cells usually have many small vacuoles

  20. Some organelles have their own DNA…. • Only two organelles have their own DNA – mitochondria and chloroplasts. • Endosymbiotic Theory – suggests that mitochondria and chloroplasts are the decendents of ancient prokaryotes that developed symbiotic relationships with ancient cells. http://micro.magnet.fsu.edu/cells/chloroplasts/images/chloroplastsfigure1.jpg http://en.citizendium.org/images/c/c7/MitochondriaSMALL2.jpg

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