Term
|
Definition
| When cells begin to stop dividing after about 50 cell divisions on average aka finite capacity for cell division. |
|
|
Term
| What forces the cell into senescence? |
|
Definition
| Insufficient telomerase activity by limiting the number of mitotic divisions. |
|
|
Term
| What do human tumors express that confers endless growth? |
|
Definition
| human telomerease reverse transcriptase (hTERT). |
|
|
Term
| What are the 3 steps in preparing tissue for study with light microscope? |
|
Definition
1) fixation by chemical to preserve tissue structure
2) infiltrated with embedding medium for sectioning
3) stain with H&E for examination |
|
|
Term
| What is tissue fixation used for? (4) |
|
Definition
1) terminate cell metabolism
2) prevent enzymatic degradation of cells and tissues by autolysis
3) kill pathogenic microorganisms such as bacteria, fungi, or viruses
4) harden tissue as a result of either cross-linking or denaturing protein molecules |
|
|
Term
| What is the main chemical used in fixation and what does it do? |
|
Definition
| formalin, preserves general structure of the cell and extracellular components by reacting with amino groups of proteins, which can maintain their ability to react with specific antibodies. |
|
|
Term
| What sorts of molecules are preserved in tissue after fixation and why? |
|
Definition
| Large molecules that do not readily dissolve such as nucleoproteins, intracellular cytoskeletal proteins, extracellular proteins and membrane phospholipid-protein complexes |
|
|
Term
| What are some examples of large molecules lost during routine fixation? |
|
Definition
| glycogen, proteoglycans and glycosaminoglycans, and soluble components |
|
|
Term
|
Definition
| ability of anion groups to react with a basic dye |
|
|
Term
| What does the reaction of anionic groups for staining vary upon? |
|
Definition
|
|
Term
|
Definition
| reaction of cationic groups with an acidic dye |
|
|
Term
| Which substances display basophilia? |
|
Definition
| heterochromatin, nucleoli, cytoplasmic components, extracellular materials |
|
|
Term
| Which substances display acidophilia? |
|
Definition
| cytoplasmic filaments, intracellular membranous components, extracellular fibers |
|
|
Term
| What is metachromasia and the underlying mechanism? |
|
Definition
| absorbance change where certain basic dyes react with tissue components that shift their normal color from blue to red; due to presence of polyanions within tissue |
|
|
Term
| What structures exhibit metachromasia? |
|
Definition
| cartilage, heparin-containing granules of mast cells, RER of plasma cells, where high concentrations of ionized sulfate and phosphate groups are found |
|
|
Term
|
Definition
| carbohydrates, glycogen in cells, mucus in various cells and tissues, basement membrane that underlies epithelia and reticular fibers in connective tissue |
|
|
Term
| What is the basis of PAS and Feulgen reactions? |
|
Definition
| ability of bleached basic fuchsin to react with aldehyde groups that results in a red color |
|
|
Term
| What is used to stain DNA? |
|
Definition
| Feulgen reaction, which relies on mild hydrochloric acid hydrolysis |
|
|
Term
| What are the 3 steps to preparing tissue for frozen section? |
|
Definition
1) freezing the tissue sample
2) sectioning frozen tissue inside a cryostat
3) staining cut sections with H&E, methylene blue or PAS |
|
|
Term
| Why would one do enzyme digestion when examining an adjacent section? |
|
Definition
| to confirm the identity of the stained material |
|
|
Term
| What can be visualized when mild aldehyde fixation is used to identify and localize enzymes? |
|
Definition
| Reaction product of the enzyme activity is visualized; a capture reagent traps the reaction product of the enzyme by precipitation |
|
|
Term
| What are the 2 types of antibodies used in immunocytochemistry? |
|
Definition
| polyclonal and monoclonal antibodies |
|
|
Term
| What is the underlying basis of immunocytochemistry? |
|
Definition
| specificity of a reaction between an antigen and an antibody |
|
|
Term
| What is the difference between poly- and monoclonal antibodies? |
|
Definition
| Polyclonal represent mixtures of different antibodies produced by many clones of B lymphocytes; monoclonal are those produced by an antibody-producing cell line consisting of a single group of identical B lymphocytes |
|
|
Term
| What is the difference between direct and indirect immunofluorescence? |
|
Definition
| When fluorescein is conjugated directly with the specific primary antibody, the method is direct (1-step); when it is conjugated with a secondary antibody, the method is indirect (2-step). |
|
|
Term
| What are the advantages of indirect immunofluorescence? |
|
Definition
1) enhances fluorescence signal emission from tissue
2) single secondary antibody can be used to localize the tissue-specific binding of several different primary antibodies |
|
|
Term
| What is the FISH procedure? |
|
Definition
| When fluorescent dyes have been combined with nucleotide probes, making it possible to visualize multiple probes at the same time |
|
|
Term
| Define hybridization and which nucleic acid bonds are strongest? weakest? |
|
Definition
| ability of ss RNA or DNA to interact with complementary sequences; strongest bonds are DNA:DNA and weakest are RNA:RNA. |
|
|
Term
| What does autoradiography do? |
|
Definition
| Makes use of a photographic emulsion placed over a tissue section to localize radioactive material within tissues. |
|
|
Term
| How does the TEM produce an image? |
|
Definition
| By interacting a beam of electrons with a specimen; beam is passed through the specimen |
|
|
Term
| What makes a portion of a specimen dark under TEM? |
|
Definition
| areas where the tissue has absorbed or scattered electrons because of their inherent density or because of heavy metals added during specimen preparation |
|
|
Term
| What can TEM do that light microscopy can't do? |
|
Definition
| Increase resolution; light microscopy can only magnify |
|
|
Term
| Describe the nucleus under light microscopy? |
|
Definition
| largest organelle w/in cell with distinct boundary; often visible nucleoli and chromatin pattern regions |
|
|
Term
| Describe the nucleolus under light microscopy? |
|
Definition
| roughly circular, basophilic region w/in nucleus |
|
|
Term
| Describe the PM under light microscopy? |
|
Definition
|
|
Term
| Describe the rER under light microscopy? |
|
Definition
| basophilic region of cytoplasm referred to as ergastoplasm |
|
|
Term
| Describe the sER under light microscopy? |
|
Definition
| not visible; cytoplasm in region of sER may exhibit distinct eosinophilia |
|
|
Term
| Describe the Golgi apparatus under light microscopy? |
|
Definition
| sometimes seen as "negative-staining" region; appears as network in heavy metal stained preps |
|
|
Term
| Describe the secretory vesicles under light microscopy? |
|
Definition
| only when they are large (ie zymogen granules in pancreas) |
|
|
Term
| Describe the mitochondria under light microscopy? |
|
Definition
| very small, dark dots; visible in living cells stained with vital dyes |
|
|
Term
| Describe the endosomes under light microscopy? |
|
Definition
|
|
Term
| Describe the lysosomes under light microscopy? |
|
Definition
| visible only after special enzyme histochemical staining |
|
|
Term
| Describe the peroxisomes under light microscopy? |
|
Definition
| visible only after special enzyme histochemical staining |
|
|
Term
| Describe the cytoskeletal elements under light microscopy? |
|
Definition
| only when organized into large structures |
|
|
Term
| Describe the ribosomes under light microscopy? |
|
Definition
|
|
Term
| Describe the glycogen under light microscopy? |
|
Definition
| "purple haze" region of cytoplasm with toluidine blue-stained specimen |
|
|
Term
| Describe the lipid droplets under light microscopy? |
|
Definition
| readily visible when very large |
|
|
Term
| Describe the nucleus under EM? |
|
Definition
| surrounded by two membranes containing NPC and perinuclear cisternal space; regions with condensed and diffuse chromatin pattern |
|
|
Term
| Describe the nucleolus under EM? |
|
Definition
| dense, nonmembranous structure containing fibrillar and granular material |
|
|
Term
| Describe the PM under EM? |
|
Definition
| external membrane and membranes surrounding membranous organelles of cell; two inner and outer electron-dense layers separated by an intermediate electron-lucent layer |
|
|
Term
| Describe the rER under EM? |
|
Definition
| flattened sheets, sacs, and tubes of membranes with attached ribosomes |
|
|
Term
| Describe the sER under EM? |
|
Definition
| flattened sheets, sacs, and tubes of membranes WITHOUT attached ribosomes |
|
|
Term
| Describe the Golgi under EM? |
|
Definition
| stack of flattened membrane sheets, often adjacent to one side of nucleus |
|
|
Term
| Describe the secretory vesicles under EM? |
|
Definition
| relatively small, membrane-bounded vesicles of uniform diameter, often polarized on one side of cell |
|
|
Term
| Describe the mitochondria under EM? |
|
Definition
| two-membrane system: outer membrane and inner membrane arranged in numerous folds (cristae) |
|
|
Term
| Describe the endosomes under EM? |
|
Definition
| tubulovesicular structures with subdivided lumen containing electron-lucent material or other smaller vesicles |
|
|
Term
| Describe the lysosomes under EM? |
|
Definition
| membrane-bounded vesicles, often electron dense |
|
|
Term
| Describe the peroxisomes under EM? |
|
Definition
| membrane-bounded vesicles, often with electron-dense crystalloid inclusions |
|
|
Term
| Describe the cytoskeletal elements under EM? |
|
Definition
| long, linear staining pattern with width and features characteristic of each filament type |
|
|
Term
| Describe the ribosomes under EM? |
|
Definition
| very small dark dots, often assoc with rER |
|
|
Term
| Describe the glycogen under EM? |
|
Definition
| nonmembranous, very dense grapelike inclusions |
|
|
Term
| Describe the lipid droplets under EM? |
|
Definition
| nonmembranous inclusions; generally appear as a void |
|
|
Term
| What is the protein that interacts most with the PM in vesicle formation? |
|
Definition
| Clathrin; some endocytosis is clathrin-independent |
|
|
Term
| What are the 3 mechanisms of endocytosis in the cell? |
|
Definition
1) pinocytosis
2) phagocytosis
3) receptor-mediated endocytosis |
|
|
Term
|
Definition
| nonspecific ingestion of fluid and small protein molecules via small vesicles; constitutive; visible with TEM; clathrin-independent |
|
|
Term
|
Definition
| ingestion of large particles; nonselective; clathrin-independent |
|
|
Term
| Describe pathway of receptor-mediated endocytosis. |
|
Definition
| cargo receptors accumulate in area of membrane; lipid raft region becomes coated pit; clathrin interacts with cargo receptor via adaptin; dynamin mediates liberation of forming clathrin-coated vesicles from PM |
|
|
Term
| Which endocytotic mechanism is clathrin-DEPENDENT? |
|
Definition
| receptor-mediated endocytosis |
|
|
Term
| What are the 2 general pathways for exocytosis? |
|
Definition
| constitutive and regulated secretory |
|
|
Term
| What is the difference between the constitutive and regulated secretory pathway? |
|
Definition
constitutive: substances are continuously delivered to transport vesicles at PM and that there are no secretory granules
regulated: regulatory event must be activated for secretion to occur and contents are stored in secretory vesicles |
|
|
Term
|
Definition
| bounds to the traveling vesicle and recognizes the "address" where vesicle needs to go and binds to tethering proteins of target membrane |
|
|
Term
| What happens after the docking complex between Rab-GTPase and its receptor has immobilized at the target membrane? |
|
Definition
| cis-SNARE complex guarantee the specificity of interaction between a particular vesicle and its target membrane and also promote membrane fusion |
|
|
Term
| How are SNARE complexes dismantled? |
|
Definition
| With the help of NSF/alpha-SNAP protein complex |
|
|
Term
| Describe early endosomes. |
|
Definition
| compartments that are restricted to a portion of the cytoplasm near the cell membrane where vesicles originating from cell membrane fuse |
|
|
Term
| Where do vesicles go from the early endosome? |
|
Definition
| Return to PM or travel to deeper structures called late endosomes, which become lysosomes |
|
|
Term
| What are the two models that explain the original and formation of endosomal compartments in the cell? |
|
Definition
1) stable compartment model
2) maturation model |
|
|
Term
| Describe the stable compartment model. |
|
Definition
| early and late endosomes are connected by vesicular transport with external environment of cell and with Golgi |
|
|
Term
| Describe the maturation model. |
|
Definition
| early endosomes are formed de novo from endocytotic vesicles from PM and matured into late endosomes |
|
|
Term
| Where are M6P receptors present? |
|
Definition
| early and late endosomes, lysosomes and Golgi |
|
|
Term
| What is another word for late endosomes? |
|
Definition
| pre-lysosomes bc they mature into lysosomes |
|
|
Term
| Compare early and late endosomes wrt structure and pH |
|
Definition
early endosomes have a tubulovesicular structure with a slightly more acidic environment than the cytoplasm;
late endosomes have a more complex structure with onionlike internal membranes, their pH is more acidic |
|
|
Term
| What is the pathway for delivery of newly synthesized lysosomal enzymes? |
|
Definition
1) synthesized and glycosylated at rER
2) enzyme folds so signal patch is formed, M6P added for further modification
3) allows enzyme to be targeted to specific proteins that possess M6P receptor activity
4) goes to TGN where it is sorted/packaged and sent to early or late endosomes |
|
|
Term
| What are multivesicular bodies (MVB)? |
|
Definition
| vesicles that are highly selective transporters between early and late endosomes |
|
|
Term
| What is the major function of early endosomes? |
|
Definition
| sort and recycle proteins internalized by endocytotic pathways |
|
|
Term
| How does pH decrease from early to late endosomes then to lysosomes? |
|
Definition
| By increased active transport of protons into endosomal compartments |
|
|
Term
| What are 4 pathways for processing internalized ligand-and-receptor complexes? |
|
Definition
1) receptor recycled and ligand degraded
2) both receptor and ligand recycled
3) both receptor and ligand degraded
4) both receptor and ligand transported through cell |
|
|
Term
| What are the 3 classes of lysosomal membrane proteins? |
|
Definition
|
|
Term
| What protects lysosomes from digestion by hydrolytic enzymes? |
|
Definition
| sugar molecules covering almost the entire luminal surface of these proteins. |
|
|
Term
| Describe generally the structure of the lysosomal membrane. |
|
Definition
| phospholipid structure containing cholesterol and lyso-bisphosphatidic acid |
|
|
Term
| What are the two pathways for lysosome biogenesis? |
|
Definition
1) constitutive secretory
2) Golgi-derived coated vesicle secretory |
|
|
Term
| What are the 3 pathways for delivering material for intracellular digestion in lysosomes? |
|
Definition
1) extracellular large particles are engulfed via phagocytosis and fuse with lysosome to create phagolysosome
2) extracellular small particles enter via endocytosis and follow pathway of early to late endosomes which finally go to lysosomes
3) intracellular particles are isolated in the cytoplasm by ER membranes and tranported to lysosomes for autophagy |
|
|
Term
| What are the 3 autophagic pathways for degradation of cytoplasmic constituents? |
|
Definition
1) macroautophagy: nonspecific, ER forms a membrane around substance to form double-membrane autophagosome vacuole, which fuses with lysosome
2) microautophagy: nonspecific, internalized by invagination of lysosomal membrane
3) chaperone-mediated direct transport: selective, requires help from hsc73 which binds to protein and helps transport into lysosome lumen |
|
|
Term
| How is the hydrolytic breakdown of lysosomal contents related to cellular aging? |
|
Definition
| production of debris-filled vacuole called residual body remain in the cell indefinitely; aka lipofuscin granules |
|
|
Term
|
Definition
| portion of cytoplasm that stains with basic dye |
|
|
Term
| Why does cytoplasm of some cells stain intensely with basic dyes? |
|
Definition
| Bc they are engaged chiefly in protein synthesis; the presence of P groups on RNA is reason for basophilic staining |
|
|
Term
|
Definition
| polyribosome complex comprised of a single mRNA bound to many ribosomes |
|
|
Term
| Where are secretory proteins synthesized? |
|
Definition
| exclusively by ribosomes of rER |
|
|
Term
| What do signal proteins attached to secretory and integral proteins do? |
|
Definition
| Instructs the newly formed peptide to pass through the membrane into the lumen of the rER cisterna |
|
|
Term
| What is the process of cotranslational insertion of protein into rER? |
|
Definition
| when hydrophobic signal domain of a forming secretory protein attaches to a receptor on membrane of rER |
|
|
Term
| How does the rER act as a quality check point in protein production? |
|
Definition
| if newly synthesized protein is not properly modified, it cannot exit the rER. |
|
|
Term
| Describe action of COP-1. |
|
Definition
| retrograde transport from CGN back to rER as part of salvage operation |
|
|
Term
| Describe action of COP-II. |
|
Definition
| anterograde transport forming rER transport vesicles desgined for the CGN |
|
|
Term
| How do cells with large amount of sER exhibit when viewed under the light microscope? |
|
Definition
| distinct eosinophilia (acidophilia) due to lack of ribosomes |
|
|
Term
| What does sER do in the liver? |
|
Definition
| detoxify enzymes with cytochrome P450 by chemically converting them into water-soluble conjugated products that can be eliminated from body |
|
|
Term
| What happens as proteins and lipids travel through the Golgi stacks? |
|
Definition
| undergo a series of posttranslational modifications that involve remodeling N-linked oligosaccharides previously added in the rER |
|
|
Term
| From the TGN, proteins exit to four possible locations. What are they? |
|
Definition
1) apical PM
2) basolateral PM
3) endosomes or lysosomes
4) apical cytoplasm |
|
|
Term
| What are the 2 protein complexes that help bring newly synthesized polypeptides into the mitochondrial cytoplasm? |
|
Definition
1) TOM complexes
2) TIM complexes |
|
|
Term
| How do substances pass through the OMM? |
|
Definition
| voltage-dependent anion channels aka mitochondrial porins |
|
|
Term
| Name three enzymes on the OMM. |
|
Definition
| phospholipase A2, monoamine oxidase, acyl coA synthetase |
|
|
Term
| The IMM is rich with what phospholipid? |
|
Definition
| cardiolipin, which makes the membrane impermeable to ions |
|
|
Term
| What are the 3 main functions of proteins on the mit cristae? |
|
Definition
1) perform oxidation reactions of respiratory ETC
2) synthesize ATP
3) regulated transport of metabolites into and out of matrix |
|
|
Term
| What are the 2 major products of the mit matrix that act as the source of electrons for ETC? |
|
Definition
|
|
Term
| What do mit matrix granules do? |
|
Definition
| store Ca and other divalent and trivalent cations |
|
|
Term
| What is chemiosmotic coupling? |
|
Definition
| Movement of protons back to the mit matrix that drives the synthesis of ATP |
|
|
Term
| What happens to the newly formed ATP? |
|
Definition
| transported from matrix to intermembrane space by voltage gradient-driven ATP/ADP exchange protein located at IMM; ATP leaves OMM to enter cytoplasm |
|
|
Term
| Mitochondria is found in 2 configurations which are... |
|
Definition
1) orthodox where cristae are prominent and matrix occupies a large part of volume
2) condensed where cristae are not easily recognized |
|
|
Term
| orthodox and condensed configurations of mitchondria relate to what? |
|
Definition
| orthodox to low level of oxidative phosphorylation and condensed to high level of oxidative phosphorylation |
|
|
Term
| How does the mit determine cell death (apoptosis)? |
|
Definition
| release of cyt c from intermembrane space into cell cytoplasm is regulated by Bcl-2 protein family; cascade effect initiated to result in apoptosis |
|
|
Term
| Describe pos and neg ends of microtubule assembly. |
|
Definition
| + end is growing end to which tubulin dimers bound to GTP are incorporated; - end contains gamma tubulin and capping proteins, tubulin dimers are bound to GDP |
|
|
Term
| Which intermediate filaments are found in all epithelial cells? |
|
Definition
| The two keratin filaments, acidic and basic cytokeratins |
|
|
Term
| Which intermediate filaments are found in muscle cells? |
|
Definition
| desmin, synemin, paranemin and nestin |
|
|
Term
| Which intermediate filaments are found in neurons? |
|
Definition
| peripherin, GFAP and all in the neurofilaments class |
|
|
Term
| Where are the lamins intermediate filaments found? |
|
Definition
| in most differentiated cells and all nucleated cells |
|
|
Term
|
Definition
|
|
Term
| What is the order in diameter size of actin, intermediate filaments and MTs? |
|
Definition
| actin filaments < intermediate filaments < MTs |
|
|
Term
| What is the shape of actin filaments? |
|
Definition
|
|
Term
| What is the shape of intermediate filaments? |
|
Definition
|
|
Term
| What is the shape of MTs? |
|
Definition
| nonbranching long hollow cylinders |
|
|
Term
| What is the basic protein subunit of actin filaments? |
|
Definition
|
|
Term
| What is the basic protein subunit of intermediate filaments? |
|
Definition
| various intermediate filament proteins |
|
|
Term
| What is the basic subunit of MTs? |
|
Definition
| dimers of alpha and beta tubulin |
|
|
Term
| What is the enzymatic activity of actin filaments? |
|
Definition
|
|
Term
| What is the enzymatic activity of intermediate filaments? |
|
Definition
|
|
Term
| What is the enzymatic activity of MTs? |
|
Definition
|
|
Term
| Which cytoskeletal elements have polarity? |
|
Definition
| actin filaments and MTs; NOT intermediate filaments |
|
|
Term
| Describe polarity of actin filaments |
|
Definition
| - end is slow growing and pointed; + end is fast growing and barbed |
|
|
Term
| Describe polarity of MTs. |
|
Definition
| - is nongrowing and embedded in MTOC; + is growing end |
|
|
Term
| Where are actin filaments located? |
|
Definition
| core of MV; terminal web; beneath PM; contractile elements of muscles and dividing cells |
|
|
Term
| Where are intermediate filaments located? |
|
Definition
| across cytoplasm connecting desmosomes and hemidesmosomes; beneath inner nuclear membrane |
|
|
Term
|
Definition
| core of cilia; mitotic spindle and centrosome |
|
|
Term
| What are major functions of actin filaments? |
|
Definition
| provide essential components to contractile elements of muscle cells |
|
|
Term
| What are major functions of intermediate filaments? |
|
Definition
| provide mechanical strength and resistance to shearing forces |
|
|
Term
| What are major functions of MTs? |
|
Definition
| provide network "railroad tracks" for movement of organelles within the cell; provide movement for cilia and chromosomes during cell division |
|
|
Term
| Describe 9+2 arrangement in cilia |
|
Definition
| 9 MTs at periphery of cilia surround 2 central MTs |
|
|
Term
| How are MTs arranged in basal bodies? |
|
Definition
| 9 triplets at the periphery of the basal body with no central pair |
|
|
Term
| How are intermediate filaments different from actin filaments and MTs? |
|
Definition
| no enzymatic activity, nonpolar, do not typically disappear and reform, have tissue specificity |
|
|
Term
| What do dyneins do in mitosis? |
|
Definition
| move chromosomes along MTs of mitotic spindle |
|
|
Term
| Functions of centrioles are divided into what two categories? |
|
Definition
1) basal body formation
2) mitotic spindle formation |
|
|
Term
| What is the purpose of basal bodies? |
|
Definition
| to help assemble cilia and flagella; formed by replication of centrioles giving rise to procentrioles, which becomes a basal body; acts as organizing center for cilium |
|
|
Term
| What do centrioles do in mitosis? |
|
Definition
| position the mitotic spindle properly by recruiting the MTOC from which astral MTs can grow and establish the axis for developing spindle |
|
|
Term
| Which appear denser in TEM: basal bodies or cilia? |
|
Definition
|
|
Term
| What does each cilium need? |
|
Definition
|
|
Term
|
Definition
| cytoplasmic or nuclear structures with characteristic staining properties formed from metabolic products of cell |
|
|
Term
| What are 5 common inclusions? |
|
Definition
1) lipofuscin
2) hemosiderin
3) glycogen
4) lipid inclusions (fat droplets)
5) crystalline inclusions |
|
|
Term
| How does lipofuscin stain and where? |
|
Definition
| brownish-gold pigment; seen in nondividing cells (neurons, skeletal and cardiac muscle) |
|
|
Term
| How does hemosiderin stain and where? |
|
Definition
| deep brown granule; cytoplasm of most cells |
|
|
Term
| How does glycogen stain and where? |
|
Definition
| clusters of granules typically unstained; liver and striated muscle |
|
|
Term
| How will glycogen compare to ribosomes when studied in a micrograph? |
|
Definition
| glycogen is considerably denser than ribosomes |
|
|
Term
| Compare euchromatin to heterochromatin. |
|
Definition
| Hetero is highly condensed chromatin (inactive) and densely staining; eu is dispersed form (active) and lightly staining, not visible in light microscope |
|
|
Term
| What are nuclear lamina formed from? |
|
Definition
| meshwork of intermediate filaments (lamins) that are arranged in a square lattice |
|
|
Term
| How are cells classified according to mitotic activity? |
|
Definition
1) static
2) stable
3) renewing (slowly and rapidly) |
|
|
Term
| Generally, what is characteristic of renewing cell populations? |
|
Definition
| display regular mitotic activity; 2 daughter cells result |
|
|
Term
| Which cells are slowly renewing? |
|
Definition
| smooth muscle cells of hollow organs, fibroblasts of uterine wall, epithelial cell of eye lens |
|
|
Term
| Which cells are rapidly renewing? |
|
Definition
| blood cells, epithelial cells, dermal fibroblasts of skin |
|
|
Term
| What are the 4 basic tissue types? |
|
Definition
1) epithelium
2) connective
3) muscle
4) nerve |
|
|
Term
| How are epithelia classified? |
|
Definition
| shapes (squamous, cuboidal and columnar) and layers (simple or stratified) |
|
|
Term
| What are the two classifications of connective tissue? |
|
Definition
| Loose (found in close association with most epithelia) and dense |
|
|
Term
| How are epithelia and connective tissue different? |
|
Definition
| epithelia are always continguous with one another and connective tissue are often separated from one another mixed with ECM |
|
|
Term
| What do all muscle types have in common? |
|
Definition
| bulk of cytoplasm consists of contractile proteins actin and myosin |
|
|
Term
| What is the structure of a neuron? |
|
Definition
| a single, long axon carries impulses away from cell body, which contains the neuron's nucleus; dendrites receive impulses and carry them toward cell body; axon terminates at a neuronal junction called a synapse and transfer impulses via neuromediators |
|
|
Term
| What are neurons called in the CNS and PNS? |
|
Definition
CNS: neuroglial cells
PNS: Schwann cells and satellite cells |
|
|
Term
| How can one differentiate between loose and dense connective tissue in a micrograph? |
|
Definition
| Loose tend to vary in size and shape while dense show less nuclei, packed fibers and thick collagen bundles that stain more intensely with blue dye |
|
|
Term
| What are 3 main characteristics of epithelia? |
|
Definition
1) closely apposed and adhere to one another by means of specific cell-to-cell adhesion molecules that form specialized cell junctions
2) exhibit functional and morphologic polarity
3) basal surface is attached to an underlying basement membrane |
|
|
Term
| What are the three morphologic surface domains of epithelia? |
|
Definition
1) apical (free surface)
2) lateral
3) basal |
|
|
Term
| What are epithelioid tissues? |
|
Definition
| cell aggregates that have characteristics of epithelia except absence of an apical domain |
|
|
Term
| How does one classify the shape for stratified epithelia? |
|
Definition
| Only the shape of cells that form the SURFACE LAYER is used to classify it |
|
|
Term
| What are the 2 special classificiations of epithelia? |
|
Definition
| pseudostratified and transitional |
|
|
Term
| Describe pseudostratified epithelium. |
|
Definition
| appears stratified but some of the cells do not reach the free surface and all rest on the basement membrane |
|
|
Term
| Describe transitional epithelium. |
|
Definition
| stratified epithelium that changes in appearance according to degree of distension of bladder |
|
|
Term
|
Definition
| epithelial lining of blood and lymphatic vessels |
|
|
Term
|
Definition
| epithelial lining of ventricles and atria of heart |
|
|
Term
|
Definition
| epithelium that lines the walls and covers the contents of closed cavities of body |
|
|
Term
| What types of epithelia cells are found at endothelium, endocardium and mesothelium? |
|
Definition
|
|
Term
| What are the 5 possible functions of epithelia? |
|
Definition
1) secretion
2) absorption
3) transport
4) protection
5) receptor function |
|
|
Term
| What are 3 structures found on the surface of the apical domain? |
|
Definition
1) MV
2) stereocilia
3) cilia |
|
|
Term
| What does the number and shape of MV correlate with? |
|
Definition
|
|
Term
| What are the actin-bundling proteins that cross-link actin filaments inside the MV? |
|
Definition
|
|
Term
| Describe the structure of actin inside MV. |
|
Definition
| Actin filaments make up the core that is anchored to villin located in the tip of the MV and extend down into the apical cytoplasm where they interact with the terminal web located below the base of the MV |
|
|
Term
|
Definition
| molecule that binds actin filament to PM of MV |
|
|
Term
| What is the terminal web composed of? |
|
Definition
| actin filaments stabilized by spectrin; myosin II and tropomyosin allows it to contract |
|
|
Term
| Where are stereocilia found? |
|
Definition
| limited to epididymis and the sensory cells of the ear |
|
|
Term
| Although stereocilia are long version of MVs, how are they different? |
|
Definition
| a plasma membrane associated molecule called EZRIN anchors the actin filaments to the PM of stereocilia; also stereocilia lack villin |
|
|
Term
|
Definition
| motile cytoplasmic structures that move fluid and particles along epithelial surfaces |
|
|
Term
| Which part of the 9+2 MT arrangement in cilia connect to the basal body? |
|
Definition
|
|
Term
| How is cilia visualized in EM? |
|
Definition
| thin, dark staining band is seen at the base of the cilia to represent basal bodies; overall gives a crew-cut appearance |
|
|
Term
| Describe the metachronal rhythm of cilia. |
|
Definition
| wave that is responsible for moving mucus over epithelial surfaces or facilitating flow of fluid and other substances through tubular organs and ducts |
|
|
Term
| What initiates ciliary movement? |
|
Definition
|
|
Term
| Describe the two strokes of the cilium. |
|
Definition
effective stroke: rapid forward movement
recovery stroke: bend toward lateral side on the slower return movement |
|
|
Term
| How are the major functions of stratified and simple epithelia different? |
|
Definition
| simple epithelia are for absorption and secretion while stratified are for barrier and protection |
|
|
Term
| Compare the transcellular and paracellular pathways for transport across epithelia. |
|
Definition
Transcellular occurs across PM of epithelia and represent active transport system;
paracellular occurs across zonula occludens between two cells |
|
|
Term
| What are the 3 transmembrane proteins that form zonula occluden? |
|
Definition
| occludin, claudin and junctional adhesion molecule (JAM) |
|
|
Term
| What binding can be found between cell adhesion molecules (CAM)? |
|
Definition
| heterotypic between different types of CAMs and homotypic between same types of CAMs |
|
|
Term
| What is the molecular structure of zonula adherens? |
|
Definition
| actin filaments of adjacent cells are attached to the E-cadherin-catenin complex by alpha-actinin and vinculin. |
|
|
Term
| What is the major function of gap junctions? |
|
Definition
| creates a conduit bw two adjacent cells for passage of small ions and informational micromolecules |
|
|
Term
| What is the major link protein between cells of a gap junction? |
|
Definition
|
|
Term
| What are the junctional features that anchor the epithelia to the ECM? |
|
Definition
| focal adhesion and hemidesmosomes |
|
|
Term
| What is the difference between focal adhesions and hemidesmosomes? |
|
Definition
| focal anchors actin filaments while hemidesmosomes anchor intermediate filaments |
|
|
Term
| What are the two junctional features that anchor two epithelia on the lateral domain? |
|
Definition
| zonula adherens and macula adherens aka desmosome |
|
|
Term
| What do desmosomes (macula adherens) and hemidesmosomes have in common? |
|
Definition
| both anchor intermediate filaments |
|
|
Term
| What is the difference between zonula adherens and macula adherens (desmosome)? |
|
Definition
| zonula couples actin filaments of two cells while macula couples intermediate filaments of two cells |
|
|
Term
| What is the location and function of zonula occludens? |
|
Definition
| Located on apical side that seals adjacent cells together by connecting actin filaments with occludins, claudins and JAMs |
|
|
Term
| How does the basement membrane exhibit? |
|
Definition
| as a homogenous layer immediately below the epithelia |
|
|
Term
| What is the difference in terminology bw basal lamina and basement membrane? |
|
Definition
| Basal lamina is used for EM and basement membrane is for light microscopy |
|
|
Term
| Describe exocrine glands. |
|
Definition
| secret products directly to surface or through epithelial ducts |
|
|
Term
| Describe endocrine glands. |
|
Definition
| lack a duct system and secret into connective tissue which enter bloodstream; products are called hormones |
|
|
Term
|
Definition
| secretory activity where cells secret a substance that does not reach the bloodstream but affects other cells within the same epithelium |
|
|
Term
| What are the 3 release mechanisms for exocrine glands? |
|
Definition
1) merocrine
2) apocrine
3) holocrine |
|
|
Term
|
Definition
| secretory product is delivered in membrane-bounded vesicles to apical surface of cell; vesicles fuse with PM and extrude contents via exocytosis |
|
|
Term
|
Definition
| secretory product is released into apical portion of cell, surrounded by a thin layer of cytoplasm within an envelope of PM |
|
|
Term
|
Definition
| secretory product accumulates within maturing cell, which undergoes programmed cell death and is discharged into lumen of gland |
|
|
Term
| How are exocrine glands classified structurally? |
|
Definition
unicellular: secretory component consists of single cells ie globlet
multicellulr: composed of more than one cell |
|
|
Term
| What is the difference between simple and compound ducts? |
|
Definition
| If duct is unbranched--simple; if duct is branched--compound |
|
|
Term
| Compare tubular, alveolar (acinar) and tubuloalveolar. |
|
Definition
Tubular: secretory portion shaped like a tube
Acinar/Alveolar: secretory portion shaped like a flask
Tubuloalveolar: secretory portion shaped like a saclike dilation |
|
|
Term
| What are the contents of mucous gland products? |
|
Definition
| viscous, slimy, extensively glycosylated constituent proteins with anionic oligosaccharides hence, PAS POSITIVE |
|
|
Term
| What are the contents of serous gland products? |
|
Definition
| watery, poorly glycosylated protein secretions |
|
|
Term
| In tissue preparation, what is the shape of nuclei and serous cells from the lumen of acinus? |
|
Definition
| nuclei are round or oval in the basal portion of the cell; demilunes or crescents |
|
|
Term
| Where are mucous glands typically found? |
|
Definition
| goblet cells, secretory cells of sublingual salivary glands, surface cells of stomach |
|
|
Term
| What is visible in the acinar cells that are serous-secreting? |
|
Definition
| zymogen granules as small round objects |
|
|
Term
| Where do mucous and serous MEMBRANES line? |
|
Definition
mucous: cavities that connect with outside of body
serous: peritoneal, pericardial and pleural cavities |
|
|
Term
| What are structural components of mucous MEMBRANES? |
|
Definition
| surface epithelium, lamina propria, basement membrane separating the epithelium from lamina propria and sometimes a deep muscularis mucosae |
|
|
Term
| What are the structural components of serous MEMBRANES? |
|
Definition
| lining epithelium, mesothelium, supporting connective tissue and a basement membrane between the two |
|
|
Term
| How are epithelia replacement cells produced? |
|
Definition
| mitotic activity of cells in the basal layer of epithelia |
|
|
Term
| What functions are related most to simple epithelia? |
|
Definition
| transport, absorption and secretion such as intestine, vascular system, digestive glands, exocrine glands, kidney |
|
|
Term
| What functions are related most to stratified epithelia? |
|
Definition
| frictional stress such as skin, oral mucosa, esophagus and vagina |
|
|
Term
| What is acinus and its structural shape? |
|
Definition
| functional group of secretory cells, each pyramidal in shape, overall spherical with lumen in center |
|
|
Term
| As a rule, where should one look if there are varying thickness of epithelium to determine the true organization? |
|
Definition
| always examine the thinnest area of an epithelium |
|
|
Term
| Where does one typically find epithelioid tissues? |
|
Definition
|
|
Term
| EM is mainly used to display what? |
|
Definition
| cell and tissue ultrastructure |
|
|
Term
| What are the phrases electron dense and lucent used to indicate? |
|
Definition
| relative darkness and lightness |
|
|
Term
| What are two histochemical techniques and how are they different? |
|
Definition
enzyme histochemistry stains substrates or end products of enzymes seen in both EM and LM
immunohistochemistry uses antibodies conjugated to specific cellular components with a visual marker for LM or EM |
|
|
Term
| What structures dye purplish blue with the basic dye haematoxylin? |
|
Definition
| Acidic structures such as nuclei, ribosomes, RER due to DNA and RNA |
|
|
Term
| Which structures dye red or pink with the acidic dye eosin? |
|
Definition
| Basic substances such as cytoplasmic proteins and mitochondria |
|
|
Term
| What are 3 possible nitrogenous compounds conjugated to glycerol via phosphate bridge? |
|
Definition
| choline, ethanolamine, serine |
|
|
Term
| What is the role of cholesterol at the PM? |
|
Definition
| stabilize and regulate fluidity of phospholipid bilayer by preventing overly dense packing while filling gaps between 'kinks' of unsaturated FA tails |
|
|
Term
| What are roles of the glycocalyx and what does it constitute? |
|
Definition
cell recognition phenomena, formation of intercellular adhesions, adsorption of molecules to cell surface, protection
constitutes glycoproteins and glycolipids forming an outer coating of PM |
|
|
Term
| What are nucleoproteins and where are they synthesized? |
|
Definition
| histone proteins or non-histone proteins which help with DNA activity in the nucleus; synthesized in cytoplasm and brought in |
|
|
Term
| Where can one find heterochromatin? |
|
Definition
|
|
Term
|
Definition
| ribosomal RNA synthesis and ribosome assembly |
|
|
Term
| What is lcoated on the inner nuclear membrane and what does it do? |
|
Definition
| nuclear lamina, which is an electron-dense layer of intermediate filaments and they link inner membrane proteins and heterochromatin |
|
|
Term
| What are the principal functions of sER? |
|
Definition
| lipid biosynthesis and membrane synthesis and repair |
|
|
Term
| What happens as proteins go through the Golgi from the rER? |
|
Definition
| Protein is glycosylated by sequential addition of sugar residues and proteins are packaged for transport to final destination |
|
|
Term
| How does the visualization of secretory granules change as they approach the lumen? |
|
Definition
| become increasingly electron dense |
|
|
Term
| Why are lysosomal degradative enzymes collectively called acid hydrolases? |
|
Definition
| Because they are optimally active at pH of 5. |
|
|
Term
| What enzymes are found in peroxisomes? |
|
Definition
| oxidases for catabolic pathways, catalase |
|
|
Term
| What does the presence of lipofuscin signify? |
|
Definition
| insoluble degradation product of organelle turnover |
|
|
Term
| What do mit matrix granules do? |
|
Definition
|
|
Term
| Where can one easily see glycogen granules and what form does it assume? |
|
Definition
| Present in large amounts in hepatocytes as glycogen inclusions and glycogen rosettes (flower shape); slightly bigger than ribosomes |
|
|
Term
| How can one identify lipid droplets in EM? |
|
Definition
| homogeneous, rounded globules |
|
|
Term
| What directions do dynein and kinesin move along the tubules? |
|
Definition
| towards and away from the cell center respectively |
|
|
Term
| How do MTs look in longitudinal and tranverse sections? |
|
Definition
| straight, unbranched structures and hollow for transverse |
|
|
Term
| What constitutes the centrosome? |
|
Definition
| pair of centrioles and the centrosome matrix |
|
|
Term
| What is the role of centrosome? |
|
Definition
| pair of centrioles duplicates and migrates to ends of cell prior to cell division to act as MTOC |
|
|
Term
| What are the roles of basement membrane? |
|
Definition
| provides metabolic support since epithelium is devoid of blood vessels, control of epithelial growth and differentiation forming a barrier to downward growth, regulates permeability |
|
|
Term
| What are the main constituents of basement membranes and external lamina? |
|
Definition
| heparan sulphate, collagen type IV, structural glycoproteins (fibronectin, laminin, entactin) |
|
|
Term
| What are the 3 layers of the basement membrane from the top? |
|
Definition
| lamina lucida, lamina densa, lamina fibroreticularis |
|
|
Term
| How does the basement membrane associate structurally with epithelia? |
|
Definition
| passes uninterrupted beneath the intercellular space between two epithelial cells |
|
|
Term
| Describe the structure of an adipocyte cell under microscopy. |
|
Definition
| nucleus is compressed and displaced to one side; cytoplasm is reduced to a small rim around the periphery; lipid droplets have no membrane |
|
|
Term
| What structures are characteristic of brown adipose tissue? |
|
Definition
| large nuclei surrounded by strongly eosinophilic cytoplasm, rich network of capillaries, crammed with mitochondria, rich in cytochromes, stored lipids in multiple droplets |
|
|
Term
| What other classification of epithelia are there besides number and shape? |
|
Definition
| presence of surface specialisations such as cilia and keratin |
|
|
Term
| Describe how pseudostratified epithelia appear? |
|
Definition
| nuclei of cells are disposed at different levels creating illusion of stratification even though all cells are resting on basement membrane |
|
|
Term
| What is the function of various cells in a transitional epithelium? |
|
Definition
| Basal cells are continuously dividing stem cells, polygonal cells are in the intermediately layers which migrate to surface where they are ultimately shed |
|
|
Term
| What is keratinisation and where does it occur? |
|
Definition
| during maturation, the epithelial cells accumulate cross-linked cytokeratin intermediate filaments resulting in a tough, non-living surface layer of squames; nuclei disappear (pyknotic; typically occurs at stratified squamous epithelium |
|
|
Term
| Describe lining of a non-distended bladder and distended bladder in terms of transitional epithelia. |
|
Definition
| Non-distended epithelia appears to be about 4-5 cell layers thick and basal cells are cuboidal; distended epithelia appear to be 2-3 cell layers thick and intermediate and surface layers are extremely flattened |
|
|
Term
| What 3 parts make up a junctional complex? |
|
Definition
1) zonula occludens
2) zonula adherens
3) macula adherentes (desmosomes) |
|
|
Term
| What are fascia occludens and where can they be found? |
|
Definition
| discontinuous strips of tight junction; found between endothelial cells lining blood vessels except in the brain |
|
|
Term
| What are 3 components of the ADHERING junction? |
|
Definition
1) transmembrane proteins
2) anchoring proteins
3) cytoskeleton |
|
|
Term
| What is the difference between connexon and connexin? |
|
Definition
| 6 connexins make up 1 connexon, which is a transmembrane channel that make up the gap junction |
|
|
Term
| What does ciliary action result from? |
|
Definition
| dynein-catalysed conversion of ATP to ADP |
|
|
Term
| What do goblet cells secret and describe their structure. |
|
Definition
| secret mucus, which is a mix of neutral and acidic proteoglycans; modified columnar epithelial cells with dense aggregate of mucigen granules |
|
|
Term
| Besides tubular or acinar, what other classification exists for the secretory component? |
|
Definition
|
|
Term
| What is the arrangement of endocrine glands? |
|
Definition
| clusters of secretory cells surrounded by rich network of small blood vessels; each cluster of endocrine cells surrounded by a basement membrane |
|
|
Term
| How do hepatocytes appear in micrograph? |
|
Definition
| large polyhedral cells with round nuclei, peripherally dispersed chromatin and prominent nucleoli; grainy glycogen inclusions and lipofuscin |
|
|
Term
| What are the responses to insulin secretion? |
|
Definition
| increase glucose uptake, increase glycogenesis, increase lipogenesis, decrease gluconeogenesis |
|
|
Term
| Describe convergence signaling. |
|
Definition
| signals from a variety of unrelated receptors, each bind to its own ligand can converge to activate a common effector |
|
|
Term
| Describe divergent signaling. |
|
Definition
| signals from the same ligand can diverge to activate a variety of different effectors leading to diverse cellular response |
|
|
Term
| Describe cross-talk signaling. |
|
Definition
| signals can be passed back and forth between different pathways |
|
|
Term
| Give an example of a convergence signaling pathway for MAP kinase cascade. |
|
Definition
| GPCR, integrins and RTKs all bind to very different ligands but can lead to formation of phosphotyrosine docking sites for the SH2 domain of the adaptor protein Grb2 which results in activation of Ras and transmission of signals down MAP kinase. |
|
|
Term
| How are different stimuli able to evoke distinct responses even though they utilize similar pathways? |
|
Definition
| Contrasting cellular responses may be due to differences in protein composition of different cell types; different cells may have different isoforms of various proteins |
|
|
Term
| Explain how cAMP is involved in cross-talk signaling. |
|
Definition
It can bind to cAMP dependent kinase PKA to block transmission of signals from Ras to Raf inhibiting the MAP kinase cascade.
At the same time, PKA and MAP kinase cascade phosphorylate the transcription factor CREB, which is then activated for binding to specific sites on DNA. |
|
|
Term
|
Definition
| simple epithelium lining blood and lymphatic vessels |
|
|
Term
|
Definition
| simple epithelium lining all body cavities |
|
|
Term
| Which is more likely to exhibit nuclei: moderately or highly keratinized cell types? |
|
Definition
|
|
Term
| What's another term for the transitional epithelium of urinary passages? |
|
Definition
|
|
Term
| What anchors the basal bodies to the apical portion of the cytoplasm? |
|
Definition
|
|
Term
| What is the MT arrangement in cilia called? Where else is this found besides cilia? |
|
Definition
| axoneme; flagellum of sperm |
|
|
Term
| What are the two classes of cell adhesion molecules? |
|
Definition
1) Ca-dependent molecules (cadherins and selectins)
2) Ca-independent molecules (CAMs and integrins) |
|
|
Term
|
Definition
| Bind to ECM and the internal cytoskeleton |
|
|
Term
| What binds the cytoplasmic domain of cadherins to actin? |
|
Definition
| catenin complex, which includes actin-binding proteins |
|
|
Term
| What are the 3 roles of the catenin complex? |
|
Definition
1) mediate a direct link to dilamentous actin
2) interact with regulatory molecules of the actin cytoskeleton
3) control adhesive state of extracellular domain of cadherins |
|
|
Term
| What are selectins and what do they do? |
|
Definition
| Ca-dependent cell adhesion molecules; bind to carbohydrates and belong to group of lectins |
|
|
Term
|
Definition
| mechanism that enables leukocytes to escape from blood circulation and reach sites of inflammation |
|
|
Term
| How are integrins different from cadherins, selectins and CAMs? |
|
Definition
|
|
Term
| How is control different for transcellular and paracellular pathways? |
|
Definition
| transcellular controlled by numerous channels and transporters; paracellular regulated by continuous intercellular contact or cell junction |
|
|
Term
| Which proteins are connecting adjacent zonula and macula adherens? |
|
Definition
| desmogleins, desmocollins, desmoplakin, plakoglobin and plakophilin |
|
|
Term
| What are the 2 components of hemidesmosomes? |
|
Definition
1) inner cytoplasmic plate
2) outer membrane plaque |
|
|
Term
| Which junction is responsible for chemical and electrical coupling between cells? |
|
Definition
|
|
Term
| What are the 2 components of basement membrane? |
|
Definition
1) basal lamina
2) reticular lamina |
|
|
Term
| What is laminin made of and what does it bind to? |
|
Definition
| made of 3 disulfide-linked polypeptide chains; bind to cell surface receptors and adhesion molecules; self-associate to form part of basal lamina |
|
|
Term
| What is fibronectin and what is it made from? |
|
Definition
| glycoprotein formed by two identical chains joined by disulfide linkages close to C-terminal; comes from fibroblasts; main adhesion molecule in ECM |
|
|
Term
| Describe treadmilling for actin polymerization. |
|
Definition
| G-actin monomers added on the barbed end of the filament move, or treadmill, along filament until lost by depolymerization at the pointed end |
|
|
Term
| What the 4 proteins that control treadmilling? |
|
Definition
| thymosin, profilin, cofilin and gelsolin |
|
|
Term
| What are the main components of microfilaments and microtubules? |
|
Definition
| actin and tubulin dimers respectively |
|
|
Term
| What are the 3 steps of dynamic instability that individual MTs undergo? |
|
Definition
1) polymerization phase
2) release of hydrolyzed phosphate
3) depolymerization phase |
|
|
Term
| What are the 3 types of MTs extending from the centrosome? |
|
Definition
1) radiating aka astral
2) kinetochore
3) polar |
|
|
Term
| What does the Fuelgen reaction specific for? |
|
Definition
|
|
Term
| Which components of the epithelia have a beltlike distribution? |
|
Definition
| tight junctions and zonula adherens |
|
|
Term
| Describe the structure of a hemidesmosome on both sides of the cell. |
|
Definition
| inner cytoplasmic plate is connected to keratin intermediate filaments; adjacent to plate is plaque which links the hemidesmosome to the basal lamina by anchoring filaments (laminin) and integrin |
|
|
Term
| Describe structure of macula adherens aka desmosomes. |
|
Definition
| adjacent plaques are connected by cadherins; desmoplakin, plakoglobin and plakophilin proteins on plaque connect to cytoplasmic keratin intermediate filaments |
|
|
Term
| What are the 4 layers of the epidermis? |
|
Definition
1) stratum corneum
2) stratum granulosum
3) stratum spinosum
4) stratum basale |
|
|
Term
| How does a blister form at the skin? |
|
Definition
| Antibodies to BPAG1 and BPAG2 trigger a response to induce mast cells to release eosinophil chemotactic factor, causing breakdown of attachment plaque of the hemidesmosome to the basal lamina |
|
|
Term
| What are the elements that connect the basal lamina to the intermediate filaments? |
|
Definition
| BPAG1, BPAG2, plectin and integrin |
|
|
Term
|
Definition
| process allowing leukocytes to leave blood vessels and mediate inflammatory responses |
|
|
Term
| How does the rER know to retain certain proteins? |
|
Definition
| Contain targeting sequence KDEL at the C-terminal; otherwise they are transported to the Golgi |
|
|
Term
| Where do proteins synthesized on free ribosomes go? |
|
Definition
| nucleus, mitochondria and peroxisomes |
|
|
Term
| Where do proteins synthesized on ER ribosomes go? |
|
Definition
|
|
Term
| What is the main function of Golgi? |
|
Definition
| addition of oligosaccharides to proteins and lipids |
|
|
Term
| What determines the functional differences between cis, medial and trans Golgi? |
|
Definition
| presence of specific glycosyltransferases |
|
|
Term
| How are lysosomal hydrolases sorted to become a primary lysosome? |
|
Definition
1) insertion of M6P into oligosaccharides attached to glycoproteins destined to lysosomes
2) presence of transmembrane M6P receptor protein in transporting vesicle |
|
|
Term
| What is the role of adaptins? |
|
Definition
| bind clathrin to vesicular membrane as well as select specific moles to be trapped in a vesicle |
|
|
Term
| Which phosphilipids are found on the outer leaflet of a PM? |
|
Definition
| phosphatidylcholine, sphingomyelin and phosphtaidylethanolamine |
|
|
Term
| Which phosphilipids are found on the inner leaflet of a PM? |
|
Definition
| phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine |
|
|
Term
| What is the glycocalyx made of and what does it do? |
|
Definition
| carbohydrates; protects cell surface and facilitates cell-cell interaction such as homing |
|
|
Term
|
Definition
| structure containing partially digested material |
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Term
| The membrane of a lysosome has what 3 characteristics? |
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Definition
1) separates hydrolytic enzymes from cytosol
2) harbors transport proteins that translocate breakdown products from lysosome into cytosol
3) contains ATP-dependent H+ pump to maintain pH of 5 |
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Term
| Describe cholesterol uptake in 6 steps. |
|
Definition
1) ligand receptor complex aggregate in coated pit
2) internalization of complex
3) internalized complex within a coated vesicle
4) clathrin coat detaches
5) primary lysosome fuses with endosome containing complex--early and late endosomes are formed
6) free receptor is recycled back to the PM |
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Term
| Describe vesicular transport with clathrin. |
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Definition
| Clathrin assembles on cytosolic side of membranes into basket like lattice. Adaptin mediates clathrin binding to vesicular membrane |
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Term
| Describe vesicular transport with COP. |
|
Definition
1) ARF bound to GTP associates with membrane of Golgi stacks to promote binding of coatomer, leading to vesicle budding
2) Hydrolysis of bound GTP changes ARF to GDP-bound leading to disassembly of vesicle coat before vesicle fuses with target membrane |
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Term
| What are the 2 steps of vesicle fusion? |
|
Definition
1) recognition of appropriate target membrane by a receptors v-SNARE (vesicle) and t-SNARE (membrane)
2) fusion induced by NSF and SNAPs |
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Term
| What do proteins targeted to the mitochondria have? |
|
Definition
1) contain terminal positively charged AA presequence
2) associated with cytosolic protein HSP70
3) recognized by receptor on mitochondrial surface
4) translocated inside mitochondria through receptors on OMM and IMM |
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Term
| What is the major protein of the peroxisome? |
|
Definition
| Catalase, which decomposes hydrogen peroxide into water |
|
|
Term
| What is the MOA of steroid hormones? |
|
Definition
1) hydrophobic steroid hormone diffuses across PM
2) steroid binds to cytosol receptor
3) steroid-cytosol receptor complex translocates into nucleus, binds to DNA and activates gene expression |
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|
Term
| What do endocrine, paracrine and autocrine cells secrete? |
|
Definition
endocrine: polypeptide or steroid hormone
paracrine/autocrine: hormones or growth factor |
|
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Term
| What is neuroendocrine signaling? |
|
Definition
| in response to a neural signal, neuroendocrine cells secret a hormone into the blood |
|
|
Term
|
Definition
| from AA L-arginine in a reaction that requires oxygen and NADPH and catalyzed by enzyme nitric oxide synthase (NOS) |
|
|
Term
| How does NO act in paracrine signaling? |
|
Definition
| increases activity of second messenger cGMP in smooth muscle cells, which cause cell muscle relaxation and blood vessel dilation |
|
|
Term
| What are 3 types of signaling molecules? |
|
Definition
1) peptides
2) neurotransmitters
3) eicosanoids |
|
|
Term
| What is autocrine signaling? |
|
Definition
| cells respond to signaling molecules that they themselves produce |
|
|
Term
| What is paracrine signaling? |
|
Definition
| signaling molecule acting locally to regulate the behavior of a nearby cell |
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|
Term
| Where do eicosanoids come from and what do they bind to? |
|
Definition
| synthesized from arachidonic acid and bind to cell surface receptors |
|
|
Term
| What members are part of eicosanoids? |
|
Definition
| prostaglandins, prostacyclin, thromboxanes and leukotrienes |
|
|
Term
| What are 3 general classes of intracellular signaling molecules? |
|
Definition
1) GPCR
2) RTK
3) cytokine receptors |
|
|
Term
|
Definition
1) alpha subunit regulates G protein activity; at rest, GDP is bound to the alpha subunit in a complex with beta and gamma
2) G protein transmits a cell surface signal to an effector
3) hormone binding stimulates release of GDP in exchange for GTP; alpha-GTP dissociates from beta and gamma and interacts with target to activate response |
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|
Term
| How does tyrosine kinase receptor work? |
|
Definition
| binding of a signaling molecule triggers receptor dimerization and autophosphorylation; downstream signaling molecules with SH2 domain bind to phosphotyrosine-containing peptides with activated receptor; imatinib mesylate binds to ATP-binding domain and prevents downstream signaling. |
|
|
Term
| What do cytokine receptors stimulate? |
|
Definition
| intracellular protein tyrosine kinases, which are not intrinsic components of the receptor |
|
|
Term
| What are the 2 classes of cytokine receptor-associated tyrosine kinases? |
|
Definition
1) Src family
2) JAK family |
|
|
Term
| Describe the cAMP pathway. |
|
Definition
1) ligand binds to cell receptor
2) adenylyl cyclase, activated by GTP bound-alpha G protein, forms cAMP from ATP
3) cAMP binds to PKA and releases catalytic subunits
4)
cAMP is degraded by cAMP dependent phosphodiesterase
5) activated catalytic subunit translocates into nucleus and phosphorylates transcription factor CREB bound to CRE
6) specific gene expression occurs |
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|
Term
| Describe the phospholipase-Ca pathway. |
|
Definition
1) signaling molecule binds and activates the protein kinase domains of a dimerized receptor
2) PLC-gamma contains SH domain that mediates its association with activated receptor protein tyrosine kinases
3) PLC-gamma catalyzes hydrolysis of PIP2 to produce DAG and IP3
4) DAG activates PKC
5) IP3 signals release of Ca from intracellular storage sites |
|
|
Term
| Describe the NF-kB transcription factor pathway. |
|
Definition
1) NF-kB associates with inhibitory subunit I-kB to form an inactive complex present in cytoplasm
2) PKC is stimulated and I-kB is phosphorylated to undergo phosphorylation-dependent degradation after ubiquitinzation
3) removal of I-kB uncovers the nuclear localization sites of the NF-kB heterodimer that translocates into the nucleus and regulates gene expression |
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|
Term
|
Definition
| protein serine and threonine kinases activated by growth factors and other signaling molecules |
|
|
Term
| Describe the ERK-MAP kinase pathway. |
|
Definition
1) ligand binding to a growth factor receptor activates Ras which interacts with Raf protein kinase
2) Raf phosphorylates and activates MEK which activates ERK by phosphorylation of tyrosine and threonine residues
3) activated ERK translocates into nucleus where it phosphorylates Elk-1
4) activated Elk-1 binds to SRE forming a complex with SRF
5) gene induction |
|
|
Term
| Describe the JAK-STAT dimer pathway |
|
Definition
1) ligand binding to a cytokine receptor leads to attachment of the inactive transcription factor STAT to receptor-associated JAK protein tyrosine kinase via their SH2 domains
2) phosphorylated STAT dimerizes
3) phosphorylated STAT dimer translocates to the nucleus where it activates transcription of target genes |
|
|
Term
| Describe keratinocytes of the stratum spinsoum. |
|
Definition
| replaced by those of stratum basale, flattened polygonal shape with distinct ovoid nucleus, lamellar bodies and tonofibrils present |
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|
Term
| Describe keratinocytes of stratum granulosum. |
|
Definition
| lamellar bodies are more numerous, product of keratinocytes (filaggrin) induce aggregation of keratins |
|
|
Term
| Describe keratinocytes of stratum lucidum/corneum. |
|
Definition
| keratinocytes have no nuclei and cytoplasm contain IF of keratin cross-linked with filaggrin, cell flattens |
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|
Term
| What are the targets of autoantibodies causing blisters? |
|
Definition
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