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The disadvantage of the SEM is A. able to view living things B. Electron beams have much shorter wavelengths than beams of light. C. more diffraction in SEMs causing poor resolution D. specimens must be chemically preserved and prepared.
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Describe to ways in which prokaryotes and eukaryotes are similar.
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Both are surrounded by a cell membrane Both contain genetic material - DNA
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BIG Question: How do cells perform their functions? 1. QoD and DO NOW 2. Review Section 7-1 Guided Notes 3. Discuss Section 7-2 4. Begin classwork on cell structures 5. HOMEWORK and Review CH 2 TESTS 6. YOU will have a short QUIZ this week on Sections 7-1 and 7-2 7-1 NOTES and Cell Booklet Requirements posted on webpage!!!
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CHAPTER 7
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The CELL is the basic unit of structure and function in living things. CELL THEORY states ◦ 1. All living things are composed of cells ◦ 2. Cells are the basic units of structure and function in living things ◦ 3. New cells are produced from living cells
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1. Robert Hooke – viewed a thin slice of cork with an early compound microscope (1665) ◦ Name them cells because of a monastery’s tiny rooms. 2. Anton van Leeuwenhoek - observed tiny organisms in drops of pond water (1674) 3. Matthias Schleiden – Concludes that all plants are made of cells (1838) 4. Theodor Schwann – Based upon Schleiden’s work, concludes animals are living so all animals are also made up of cells (1839)
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5. Rudolph Virchow – proposes that all cells come from existing cells completing the cell theory (1855) 6. Lynn Margulis – idea that certain organelles were once free living organisms ◦ Mitochondria and chloroplast both contain their own DNA. ◦ Endosymbiont Theory – Prokaryotic organisms (mitochondria and chloroplasts) were once free living but began a symbiotic relationship with larger multi-cellular organisms.
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Follow molecules through cells using fluorescent labels and light microscopy Build 3-D models with confocal light microscopy ◦ Scans cells with a laser beam Produce movies of cells as they grow, divide, and develop with High-resolution Video Technology
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Light microscope –resolution of image limited ◦ Unable to visualize tiny structures Electron microscope – electron wavelengths much shorter than light wavelengths ◦ View details up to 1000x smaller than light microscope images TEM (Transmission electron microscope) – explores cell structures and large protein molecules SEM (Scanning electron microscope) – scans surface of a specimen. 3-D images. Must be in a vacuum and specimens must be preserved Unable to study living things
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Scanning probe microscope – traces the surface of a sample. ◦ Able to observe single atoms ◦ Can operate in open air ◦ Show samples in solution ◦ Study surfaces ◦ Image DNA, Protein molecules, and other important biological structures
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Both are surrounded by a cell membrane Both contain DNA – the molecule that carries biological information
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Do not contain a nucleus Smaller and simpler Genetic material is free floating within the cell Grow, reproduce, respond to environment, and some can move along surfaces or swim through liquids Examples are bacteria
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Contain a nucleus that contains DNA separate from rest of cell Larger and more complex Dozens of Highly specialized membranes and structures Single celled to large complex multi-cellular organisms Plants, animals, fungi, and protists (algae)
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