Cytology
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48 terms
Terms | Definitions |
|---|---|
 the cell | a mass of protoplasm limited in space by a membrane |
| protoplasm | "living matter" composed of cytoplasm and nucleoplasm |
| organelles | "little organs"- have distinct structure, perform specific energy requiring functions |
| inclusions | storage components (glycogen, lipids, lysosomes) |
| plasmalemma (plasma membrane) | selective barrier between the environment and cytoplasm |
| trilaminar structure | 1. phospholipid group 2. phosphate group 3. chain of fatty acids |
| glycocalyx | cell coat =carbohydrates that extend from cell membrane -made either from proteins in external face of plasma membrane (glycoprotein) or from phospholipid molecules (glycolipid) -function: cell to cell recognition/adhesion |
| globular proteins | move around and spin with plasma membrane =ion channels, pumps, receptors, transducers, enzymes |
| nucleus | contains genetic material (nucleoplasm) surrounded by nuclear envelope |
| heterochromatin - 3 types | inactive chromatin, dense coiled DNA, dark stain on EM, basophilic on LM 1. marginal: near edge 2. karyosomes: not near edge, in space 3. nucleolar associated chromatin: near nucleolus |
| euchromatin | uncoiled DNA, more active, lighter stain on EM, unstained on LM |
| nucleolus | site of rRNA synthesis |
| nuclear lamina | make up nuclear cytoskeleton =intermediate filament protein (lamins), serve as scaffolding for nuclear components -lie adjacent to inner surface of nuclear envelope (between membrane and marginal heterochromatin) -lamins differ from intermediate filaments in cytosol (disassemble during mitosis) |
| nuclear pores | 75 nm; allow passage of mRNA into cytoplasm |
| Ribosomes | made of rRNA and protein involved in translation; mRNA -> protein |
| Intracellular protein synthesis | occurs on free polyribosomes stay in cell |
| extracellular protein synthesis | occurs on ribosome in ER includes proteins bound for membrane leave sell |
| rER | studded with ribosomes, flat protein synthesis for export or intramembrane protein |
| ribophorin | an integral protein in the rER that bind ribosomes to the ER |
| sER | not involved with protein synthesis, tubular contains no ribosomes Function: 1. synthesis of: steroid hormones,glycogen/lipids,HCl in gut 2. stores Ca2+ (sarcoplasmic reticulum) 3. drug detoxification (in liver) |
| coatomers (COP1, COP2) | transfer vesicles that move proteins (associated with golgi) COP1: retrograde transport; from golgi to rER COP2: anterograde transport; from rER to golgi |
| golgi apparatus | site of protein modification -transfer vesicles move to forming face of golgi -produces glycocalyx for integral membrane |
| lysosomes | formed at golgi, membrane bound, contains hydrolytic enzymes for digestion... primary = new, secondary = actively digesting Function: 1. breakdown of cell constituents 2. cell remodeling 3. normal turnover of organelles 4. normal turnover of macromolecules 5. breakdown of bacteria |
| Tay Sach's | lipid metabolism defect (autosomal recessive) -missing enzyme for splitting off hexose from ganglioside (hexosaminidase) -ganglioside (glycolipid in gray matter) accumulates in neural tissue causing retardation and childhood death |
| peroxisomes | contain oxidative enzymes -catalase: breaks down peroxide, preventing free radical formation |
| mitochondria | provides energy for the cell in form of ATP, contains own DNA and ribosome for self replication -calcium sink -heat production (brown fat) -present in all cells except terminal kerotinacytes and RBCs |
| microtubules | largest organelle of cytoskeleton, hollow and non-branching, 25 nm diameter -protein polymer made of tubulin subunits, present in all cells -polymerization of tubulin is reversible and dependent on ATP, pH, and [Ca2+] -can change length -line up to form spindle fibers during mitosis |
| microtubule associated proteins (MAPs) | -link MT to other structures -important for intracellular shuttling and transport |
| Microtubule function | 1. provide physical support for cells via cytoskeleton 2. intracellular movement (chromosome movement, ciliary movement) 3. intracellular transport of secretory products 4. involved with cell division |
| intermediate filaments (4 types) | not hollow, 10 nm diameter, protein polymer, relatively stable compared to MT, or MF -all cells contain some type of IF 1. keratins: all epithelial cells 2. vimentin: not found in all cells 3. neurofilaments: only in neurons 4. lamins: found in all nucleated cells |
| microfilaments (2 types) | 5 nm diameter, protein polymer, present in all cells -actin and myosin -Functions: 1. contraction (cellular movement) 2. cytokinesis 3. endocytosis 4. ameboid movement 5. structural support |
| centrioles | made of MT, found in region of cell called microtubule organizing center (MTOC) -location: near nucleus, 2 per cell -structure: 9x3 MT arrangement, CCO pattern -function: during cell division, migrates to opposite poles of cell; serves as organizing center for mitotic spindles |
| cilia (3 portions) | 1. shaft (axoneme) - 9x2 +2 MT arrangement surrounded by a plasma membrane 2. basal body - 9x3 3. rootlet - anchors cilia to cytoskeleton |
| axoneme | -9 peripheral doublets, CO arrangement -has Dynein protein that cause movement -central sheath (protein) -radial spokes (protein); connect doublets to sheath |
| inclusions | -lipid or fat -glycogen: alpha = single, beta = cluster -residual body - tertiary lysosome (lipofuscin accumulates with age) |
| microvilli | -aka striated border, brush border -finger like extensions of plasma membrane -contain villin (anchor at tip) -actin, fascin, and fibrin -terminal web = spectrin, myosin II (rigid), tropomyosin -function: increase surface area |
| stereocilia | =very long microvilli - found in sensory organ of the ear and male reproductive system -NOT a cilia |
| tight junction | -aka zonula occludens -connect ep. cell to ep. cell -membrane in direct contact -Function = tight seal, prevent leaking, not strong attachment |
| belt desmosome | -aka zonula adherens -connects ep. cell to ep. cell -function: keeps cells from being pulled apart |
| fascia adherens | -attachment between non-ep. cells, mostly in cardiac muscle cells, similar to belt desmosomes |
| desmosome | -aka macula adherens, spot desmosome -connect cell to cell of all tissue types -contain tonofilaments -has cytoplasmic plaque, transmembrane linker protein, and dense intermediate line -holds cells together tightly |
| hemidesmosome | -connect epithelia to connective tissue -has tonofilaments, cytoplasmic plaque, linker proteins |
| gap junction | -aka nexus -2 membranes don't touch, cell-cell communication -made of 6 connexin subunits (1 connexon) -Function: cell-cell comm., electrochemical coupling, peptides move from cell-cell |
| phagocytosis | -aka clathrin independent and actin dependent endocytosis -ingestion of larger particles (>1micron), material not in solution -involves actin (MF) polymerization -involves receptors that bind to ligands which effect specific changes in the cell |
| pinocytosis | -aka clathrin independent endocytosis, cell drinking -ingestion of material in solution -bulk transport (non-specific) = involves caveolae (uncoated vesicles) but doesn't involve receptors |
| receptor mediated endocytosis | -aka clathrin dependent endocytosis -clathrin = coated pit -has coated vesicles -clathrin coat made of triskelions involved in the invagination and final pinch off to form the vesicle |
| LDL endocytosis | -receptor mediated endocytosis, degraded by lysosome (asialoglycoproteins) -LDL receptor bind to LDL protein, internalized in clathrin coated pit then pinched off into a vesicle -clathrin coat depolymerizes into triskelions -uncoated vesicle = endosome -CURL = pH 5 causes LDL to dissociate from LDL receptors, receptors bud off and recycled |
| fate of receptor/ligand | 1. receptor recycled and ligand degraded 2. receptor and ligand recycled 3. receptor and ligand degraded 4. both tranported through cell |
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