exercise 5
Terms
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- cell
- structural and functional unit of all living things
- nucleus
- round or oval structure near the center of the cell; contains the genetic material;
- chromatin
- the way the genetic material is when not dividing; thin, threadlike loosely dispersed in nucleus
- cromosomes
- DNA when cel is dividing; dense, darkly staining rodlike bodies
- nucleoli
- compoised of proteins and RNA; assembly sites for ribosomal particles
- nuclear envelop
- double layer; binds the bucleus; has nuclear pores
- Plasma membrane
- separates cell contents from environment; phospholipids and globular protein molecules; fluid mosaic model;protective barrier; decides what enters and leaves;
- microvilli
- minute fingerlike progjections or folds that reatly increase the surface area of the cell available for absorption or passage o material and for the binding of signaling molecules
- ribosomes
- denely staining, roughly sphericle bodies composed of RNa and protein; sites of protein synthesis; floating or on RER
- ER
- highly folded system of membranous tubules and cisternae that extends throughout the cytoplasm; continuous witht the nuclear envelope;
- RER
- has ribosomes; modify and store the newly formed proteins and dispatch to other areas of the cell; extremely plentiful in organs that create lots of protein
- smooth er
- produces lipids and hormones-- drug detoxification
- Golgi
- stack of flattened sacs w/ bulbous ends; prtoeins delivered to it from the ER are modified, segregated, and packaed into membrane vesicles
- Lysosomes
- membranebound sacs containing digestive enzymes; acid hydrolases; dgigest worn-out cell structures and foreign substances; "suicide sacs"
- peroxisomes
- like lysosomes, contain enzymes; oxidases detoxify harmful substances, mainly free radicals; detox
- mitochondria
- rod shaped bodies w/ double membrane wall; enzymes catalyze the reactions of the Krebs cycle; power house of the cell
- cytoskeletal elements
- support and move substances w/in the cell: microtubules, intermediate filaments, microfilaments
- microtubules
- slender tubules formed of tubulins; have ability to aggregate and disaggregate spontaneously; organize cytoskeloton and direct formation of spindle; ; transport of substances down lenghth of elongated cells, suspend organelles, elp maintain cell shape
- intermediate filaments
- stable proteinaceous cytoskeletal elements that as wires to resist mechanical (pulling) forces acting on cells
- microfilaments
- ribbon o cordlike elements; formed of contractile proteins (mainly actin) ; can shorten and relax, so important in mobility;
- centrioles
- paired; rodshaped bodies that lie at right angles to each other; each centriole composed of 9 triples off microtubules; direct formation of mitotic spindle and form cilia and flagella
- inclusions
- not active in metabolic machinery of cell; stored foods, pigment granules, crystals o various types, water vacuoles, foreign materials