•What we just viewed was a cell dealing with “incoming” materials: phagocytosis. Endomembrane System at Work •What about materials that are produced in the cells that either stick around or are “outgoing”?
Endomembrane System at Work mRNA in cytoplasm ER Signal sequence? Ribosome remains free in cytoplasm Trans-membrane? Goes back ER Lysosome“zip code” signal sequence? mRNA Binds Ribosomes Translation starts
Peroxisomes • Oxidizing enzymes • Detoxification • Byproducts – H2O2 – Hazardous to cell – H20 + H2 Large protein crystal
Mitochondria • Produces ATP • Double membrane • Contains a separate, circular chromosome and its own ribosomes. • Reproduce separately from cell division. ATP
Chloroplasts • Photosynthesis • Double membrane • Membranous sacks called thylakoids • Separate circular chromosome
Mitochondria & Chloroplasts: Organelles or Something Else? • 2 membranes • Possess their own DNA – Respiration and photosynthesis • Undergo binary fission to “reproduce” • What type of organism does this sound like? • Endosymbiotic Theory of Cell Evolution
Cell Wall • Plants and Fungi • Added structure • Prevents dehydration
Plant Vacuoles • Plants lack lysosomes. • Can take up 80% of the cell’s volume. • Water storage • Enzymes as well.
Cytoskeleton Fibers: 3 Main Types • Microfilaments • Intermediate Filaments • Microtubules
Cytoskeleton Fibers • Microfilaments – Actin subunits (protein) – Cell division • Cleavage furrow formation – Involved in muscle contraction – Cytoplasmic streaming in plant cells.
Cytoskeleton Fibers • Intermediate Filaments – Supercoiled keratin proteins – Anchors nucleus in the cell
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- Fall '13
- Bacteria, Plant Cell Wall, Eukaryote Cell Communication, Animal Cell Traits