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Unformatted text preview: AP Biology Unit One: Cells and their Environment You should already know about organelles. Microscopes Cytology Study of cell structure Magnification Ratio of an objects image to its real size. Resolving Power Clarity of image Minimum distance between two distinct points Scanning Electron Microscope (SEM) Better 3-D image Coat image with metallic atoms Able to see surface images Transmission Electron Microscope Uses electromagnets to transmit beam e- through specimen Thinly sliced specimens needed Tilt specimen for 3-D effect Study internal ultrastructure Using a Light Microscope Always start at lowest objective Move stage up and down until focused Then adjust fine tuning (from this point on never touch the coarse/big knob) Move up objectives Use oil on highest power Storage: Wrap cord around base. Lowest objective. Stage down. What make prokaryotes different? Lack most organelles and other membranous structures Lack chloroplasts (conduct photosynthesis on plasma membrane) Large DNA molecule and small circular plasmids flagella like structures made of flagellin (not tubulin) that rotate (not undulate) Endosymbiotic Hypothesis 1. Organelles are descendents of prokaryotes 2. Evidence Known symbiotic relationships exist between prokaryotes and eukaryotes that may have become obligatory Mitochondria and chloroplasts have own ribosomes and chromosomes; can build their own membranes Organelle chromosomes similar to prokaryote chromosomes (circular, not wound on proteins) Ribosomes of mitochondria and chloroplasts are more similar to those of bacteria rather than to those of the eukaryote chromosome Mitochondria and chloroplast able to replicate 3. Examples 1. Amoeba and bacteria Bacteria divide inside amoeba each daughter amoeba had bacteria 2. Aerobic and photosynthetic bacteria Form symbiotic relationship Cell Structure Cytoskeleton A network of fibers extending throughout the cytoplasm. Organizes the structures and activities of the cell Functions 1. Enables cell to maintain or change shape 2. Anchor organelles and enzymes 3. Transport organelles 4. Aid in cell movement 3 types of fibers (in decreasing diameter) 1. Microtubules 2. Intermediate Filaments 3. Microfilaments (Actin Filaments) Microtubules Hollow rods Made of globular protein tubulin dimers and forms twist together to form helix) grow or shrink as more tubulin molecules are added or removed....
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This note was uploaded on 03/28/2011 for the course BILD 1 taught by Professor Chen during the Winter '11 term at UC Riverside.
- Winter '11