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BIO Ch 14 III
BIO 309 Chapter 14 -cell-cell interactions
| Question | Answer |
|---|---|
| direct interactions between cells are critical to | the development and function of multicellular organisms |
| some cell-ell interactions are transient, such as the interactions between ______ and the interactions that direct ______ to _____ | cells of the immune system, white blood cells, sites of tissue inflammation |
| stable cell-cell interactions play a role in | organization of tissues |
| specialized types of junctions provide a mechanism for | rapid communication between cells |
| cell-cell adhesion is a selective process such that | cells adhere only to other cells of specific types |
| selective cell-cell adhesion is mediated by | cell adhesion molecules |
| cell adhesion molecules are | transmembrane proteins |
| fxn of cell adhesion molecules | mediate selective cell-cell adhesion |
| cell adhesion molecules can be _____ | divided into 4 groups |
| the four groups of cell adhesion molecules | selectins, integrins, Ig superfamily, Cadherins |
| cell adhesion mediated by ______ requires ____ | selectins, integrins and most cadherins, Ca2+, Mg 2+ or Mn2+ |
| many adhesive interactions between cells are ___-dependent | cation |
| the selectins mediate transient interactions between | leukocytes and endothelial cells or blood platelets |
| there are ___ members of the selectin family : | 3, E-selectin, P-selectin,L-selectin |
| e-selectin expressed on | endothelial cells |
| p-selectin expressed on | platelets |
| l-selectin expressed on | leukocytes |
| selectins recognize | cell surface carbohydrates |
| one of the critical roles of selectins is to initiate the interactions between __ and ___ during the migration of ____ to ____ | leukocytes, endothelial cells, leukocytes, sites of inflammation |
| in the process of attachment of leukocytes to sites of inflammation, the _____ first mediate _____ | selectins, initial adhesion of leukocytes to endothelial cells |
| ICAM stands for | intracellular adhesion molecules |
| after initial adhesion of leukocytes to endothelial cells by selectins during inflammation, the formation of ___ occurs, in which ____ on the ____ bind to ___ | more stable adhesion, integrins on the surface of leukocytes, ICAMs |
| ICAMs are members of the _____ | Ig superfamily |
| ICAMs are expressed on | surface of endothelial cells |
| After binding of ICAMs, the ____ are able to _____ and ___ | leukocytes, penetrate the walls of the capillaries, enter the underlying tissue |
| leukocytes leave the circulation at ____ by interacting with the ____ of ____ | sites of tissue inflammation, endothelial cells, capillary walls |
| in the second step of attachment of leukocytes to endothelial cells in inflammation, __ bind to ICAMs | integrins |
| the binding of integrins to ICAMs is an example of | heterophilic interaction |
| heterophilic interaction | an adhesion molecule on the surface of one cell recognizes a different molecule on the surface of another cell |
| homophilic interaction | molecule on the surface of one cell binds to the same molecule on the surface of another cell |
| members of the Ig superfamily can mediate ___ interactions | heterophilic and homophilic |
| homophilic binding can lead to ___ between ___ | selective adhesion, cells of the same type |
| there are more than __ members of the Ig superfamily | 100 |
| the Ig superfamily is a family of ____ containing___- | CAMs, domains similar to immunoglobin |
| the cadherins have about ___ members | 80 |
| cadherins share a ____ that ____ | conserved extracellular domain, mediates largely homophilic interactions |
| cadherins are involved in | selective adhesion between embryonic cells, formation of specific synapses in the nervous system, maintenance of stable junctions between cells |
| stable adhesion juntions involving the cytoskeletons of adjacent cells are usually based on | cadherins |
| cell-cell interactions mediated by selectins, integrins, and Ig superfamily are generally | transient |
| what are the types of cell-cell junctions | adherens junctions and desmosomes |
| the adherens junction anchors the __ | actin cytoskeleton |
| basic components of adherens junction | a-catenin, B-catenin, p120, nectin, transmembrane cadherins |
| B-catenin and p120 are members of the __family | armadillo protein |
| in adherens junction, B-catenin binds to | cytosolic tail of cadherins, a-catenin |
| in adherens junction, a-catenin binds to | b-catenin, actin |
| in adherens junction, p120 binds to | cytosolic tail of cadherins |
| function of b-catenin in adherens junction | maintain stability of junction |
| function of p120 in adherens junction | maintain stability of junction |
| at stable cell-cell juntions, members of the protein armadillo family serve to ____ | link cadherins to the cytoskeleton |
| nectin is a | cell adhesion molecule |
| nectins interact in a __ manner | homophilic |
| nectins can also bind heterolitically to ____ in the ____ | different nectins, membrane of other cell |
| cell adhesions are initally mediated by interactions between | nectins |
| the initial interaction of nectins at cell adhesions then ____ | recruits actin-binding proteins |
| the recruitment of actin-binding proteins to the cell adhesion begins | assembly of the mature junction |
| a desmosome is a region of contact between epithelial cells in which ____ are anchored to ____ | keratin filaments, the plasma membrane |
| an adherens junction is a region of cell-cell contact in which the ___ is anchored to ____ | actin cytoskeleton, the plasma membrane |
| desmosomes directly link the ____ of ____ | intermiediate filament cytoskeleton, adjacent cells |
| what are the transmembrane cadherins in desmosomes | desmoglein, desmocollin |
| the transmembrane cadherins in desmosomes bind by ____ across the juntion | heterophilic interaction |
| the transmembrane cadherins in desmosomes bind to the intermediate filaments via | plakins |
| what armadillo family proteins are present in desmosomes | plakoglobin and plakophillin |
| what is the function of plakoglobin and plakophilin in desmosomes | bind to cytosolic tail of transmembrane cadherins and the intermediate-filament binding protein |
| what is the intermediate-filament binding protein in desmosomes | desmoplakin |
| desmoplakin is a member of the | plakin family |
| what member of the plakin family is present in desmosomes | desmoplakin |
| all components of desmosome | desmoglein, desmocollin, plakophilin, plakoglobin, desmoplakin, intermediate filaments |
| components of desmosome, family member, and what they bind to. | desmoglein & desmocollin: transmembrane cadherins, bind to plakoglobin & plakophilin & each other | plakoglobin and plakophilin: armadillo protein family, bind to cadherins and desmoplakin | desmoplakin, plakin family, binds to armadillo proteins & IFs |
| the strength of desmosomal links is a property of | the intermediate filaments and the various interactions |
| ____ for the ___ and ____ allow tissue-specific variation in desmosome properties | multiple genes, desmosomal cadherins, armadillo family proteins |
| tight junctions are critically important to the function of ___ as_____ | epithelial cell sheets, barriers between fluid compartments |
| tight junctions play two roles in separating liquid compartments: | 1) prevent free passage of molecules between cells of epithelial sheet 2) separate basolateral and apical domains by preventing free diffusion of lipids and membrane proteins between them |
| tight junctions provide minimal ___, thus are usually found in___ | adhesive strength, junctional complex |
| tight junctions are very effective | seals of the extracellular space |
| junctional complex | tight junction, adherens junction, desmosome |
| tight junctions are formed by _____ that _____ | a network of protein strands, continues around the entire circumference of the cell |
| each strand in the protein network family is composed of transmembrane proteins of the ____ families | occludin, claudin, and junctional adhesion molecule (JAM) |
| all three of the proteins in the protein strans of tight junctions bind to ___ on ___ | similar proteins, adjacent cells |
| the cytosolic tails of the proteins in tight junctions are associated with proteins of the ___ family | zonula |
| the association of the protein in tight junctions with zonula proteins serves to | link the junction to the actin cytoskeleton and hold it in place on the plasma membrane |
| ___ may also be present in tight junctions | nectins |
| the role of nectins in tight junctions | recruiting claudins |
| tight junctions are the ____ between ____ | closest known contact, adjacent cells |
| tight junctions virtually exclude the | passage of molecules between cells |
| what links to the actin filaments in tight junctions? | zonula proteins |
| JAM stands for | junctional adhesion molecule |
| JAMs have ___ domains | 2 Ig |
| components of tight junction | occludin, claudin, JAMs, zonula proteins, nectins |
| linkge to the acitn cytoskeleton in tight junctions serves to | hold junction in place |
| within an individual tissue, cells are often linked by | gap junctions |
| gap junctions provide | direct connections between the cytoplasms of adjacent cells |
| gap junctions are ____ through the ____ that ____ | open channels, plasma membrane, allow diffusion of ions and small molecules |
| gap junctions prevent the passage of | proteins and nucleic acids |
| gap junctions connect the ___ and ____ of the cells they connect | metabolic activities, electric responses |
| most cells communicate by | gap junctions |
| in electrically excitable cells, the passage of ions through gap junctions serves to _________ of ___ | couple and synchronize the contractions, neighboring cells |
| gap junctions allow the passage of some ____, such as ___ and ____, which potentially coordinates ____ | signaling molecules, Ca2+ and CAMP, responses of cells in tissues |
| gap junctions are constructed of proteins of the __ family | connexin |
| the connexins are a family of | transmembrane proteins |
| the connexin family consists of __ human proteins | 21 |
| connexon | cylinder with aqueous pore in the middle, gap junction |
| six connexins assemble in a gap junction to form a | connexon |
| a connexon is formed from | 6 connexins |
| how is the open channel in the gap junction formed | alignment of connexons in adjacent cells |
| conbinations of various gap junction proteins give rise to ___ with ___ | various connexons, various properties |
| an electrical synapse is made up of ___ that ____ | specialized assmelblies of gap junctions, occur on specific nerve cells |
| specialized assemblies of gap junctions that occur in specific nerve cells | electrical synapse |
| cardiomyocytes use gap junctions to virtually ____ all ____ in ___ at the same time | depolarize, muscle cells, atria or ventricles |
| adhesion between plant cells is mediated by __, rather than by transmembrane proteins | their cell walls |
| ___ acts as a glue to hold adjacent plant cells together | middle lamella |
| the middle lamella is rich in (in plants) | pectin |
| the middle lamella in plants is a region of the | cell wall |
| adjacent plant cells sometimes communicate with each other through ___ | plasmodesmata |
| plasmodesmata | cytoplasmic connections through which plant cells sometimes communicate |
| plant cell walls, due to their rigiditiy, do not require the formation of ____ such as in ___ | cytoskeletal links, desmosomes and adherens junctions |
| plasmodesmata function analogously to | gap junctions |
| integrins recognize the __ as a ligand | extracellular matrix, Ig superfamily |
| Ig superfamily recognize __ as a ligand | integrins, other Ig superfamily proteins |
| Cadherins recognize ___ as a ligand | other cadherins |
| selectins recognize __ as a ligand | carbohydrates |
| tight junctions allow transport of | ions and small molecules |
Created by:
flash33101