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SI session Sept. 11 Ch. 1,3,4,5 answers

SI session Sept. 11 Ch. 1,3,4,5 answers - Kaiser Imam BIOL...

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Kaiser Imam September 11, 2007 BIOL 215 SI Session Chapters 1, 3, 4, 5 Chapter 1: A Preview of the Cell 1. List the three statements of the cell theory: a) All organisms consist of one or more cells b) The cell is the basic unit of structure for all organisms c) All cells arise only from preexisting cells 2. What is the significance of Friedrich Wohler’s 1828 experiment in which he synthesized urea in the laboratory? Urea is normally produced in animals as a by-product of protein degradation. Wohler’s experiment showed that an organic compound of biological origin could be synthesized from inorganic starting materials. This showed that biological systems are subject to the same laws of chemistry and physics that apply to the nonliving world. Chapter 4: Cells and Organelles 3. Describe some differences between prokaryotic and eukaryotic cells: Prokaryotes Eukaryotes 1
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Do not have a nucleus; genome kept in nucleoid region Do not have membrane bound organelles No cytoskeleton (microtubules, microfilaments, etc.) Cannot undergo endocytosis or exocytosis Divide by binary fission (cell splitting) DNA not associated with many proteins mRNA not processed Prokaryotic cells are usually smaller than eukaryotic cells Have a membrane bounded nucleus Have many membrane bounded organelles Cytoskeleton made up of microtubules, microfilaments, etc. Can undergo endocytosis/exocytosis Reproduce by mitosis or meiosis DNA wrapped around histone proteins mRNA is processed before leaving nucleus Eukaryotic cells are usually larger than prokaryotic cells 4. List 3 factors that limit cell size: a) Surface area to volume ratio: area available for the exchange of material between a cell and its environment b) Rates of diffusion: nutrients and waste products must be able to diffuse through cells c) Concentrations of reactants and catalysts: enzymes and substrates have a harder time finding each other in larger cells 5. What general purpose do organelles serve in cells? Organelles are meant to compartmentalize certain cellular processes and activities into localized areas so that large amounts of reactants and catalysts are not needed throughout the cell. This solves some of the problems posed by increasing cell size as substrate and enzyme molecules do not have to diffuse as far. 6. Compare the sizes of the following organelles: An animal cell ((smaller/larger/ about the same ) a plant cell An animal cell (smaller/ larger /about the same) a bacterium cell Mitochondria (smaller/larger/ about the same ) a bacterium cell Mitochondria ( smaller /larger/about the same) a chloroplast chloroplast ( smaller /larger/about the same) a nucleus Bacterium cell < Animal cell ≈ Plant Cell Mitochondria ≈ Bacterium cell < Chloroplast < Nucleus 2
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7. List the functions of the following organelles: Structure Function Notes Nucleolus Production of ribosomes Present only in eukaryotic cells inside the nucleus, seen as a dark region under a microscope Nuclear Envelope
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