Interactions Between Cells and Their Environment

hemidesmosomes

basal attachments of epithelial cells to the basement membrane.

what is a glycocalyx?

cell coat, carbohydrate projects forming the plasma membrane. glycocalyx is cell-cell and cell-substratum interactions.

how are epithelial and connective tissue formed?

interactions with extracellular material.

B-catenin

key element in a signaling pathway leading from cell surface to nucleus.

Fibronectin?

linear array of polypeptides giving a modular structure, each polypeptide is 30 fn modules. fn has binding sites for other components of the ECM. fn guides migrating cells during embryogensis.

Synthesis of a plant cell wall?

cellulose molecules are polymerized at the cell surface, glucose is added to the end of a growing cellulose moelcule by cellulose synthase. materials are synthesized in the cytoplasm and taken to the cell surface in secretory vesicles.

basement membrane scaffold?

collagen, laminen, connected by entactin.

the cytoplasmic domain of the cadherin?

connected to the actin filaments of the cytoskeleton.

Basement membrane?

continuous sheet that underlies epithelial tissue and surrounds blood vessels, helps maintain cell attachment, serves as substratum for cell migration, forms a barrier to macromolecules.

plasmodesmata?

cytoplasmic channels passing through cell walls of plant cells. lined by plasma membrane, contain a central desmotubule, serves as sites of cell-cell communication

Desmosomes

disk shaped adhesive junctions between cells found in tissues. contain cadherins that link the two cells across a narrow gap. these cadherins have desmogleins and desmocollins.

Laminins

extracellular glycoproteins consisting of three polypeptide chains linked by disulfide bonds.

selectins

family of integral membrane glycoproteins. small cytoplasm, a single membrane, large extracellular segment e selectin - endothelial cells p-selectin - platelets and endothelial cells L - selectin- white blood cells.

integrins

family of membrane proteins composed of heterodimers with alpha and beta subunits integrate extracellular and intracellular environments, adhesion of cells to their substratum or other cells.

Collagens?

fibruous glycoproteins found only in the ECM. most abundant protein in the human body. it is a triple helix of three helical alpha chains.

Adherens junction

form belts near apical surface called junctional complex.

Adherens junction

form belts near apical surfaces

Cadherins?

glycoproteins that mediate CA2+ they join cells of similar types to one another by preferential binding. E-cadherin - epithelial N-cadherin - neural P-cadherin - placental transmitting signals from the ECM to the cytoplasm. mediate many of the changes in adhesive contacts during embryonic development. , epithelial-mesenchymal transition. epithelia tight associations, mesenchyme loose associations

how are ECM materials degraded?

matrix metalloproteinases, regulated by tissue inhibitor of metalloproteinases.

immunoglobulin superfamily

most proteins are involved in immune functions. most mediate interactino of lymphocytes. mediate adhesion VCAM - vascular cell-adhesion NCAM - neural cell adhesion L1 - neural development

When is there differentiation in mammary glands?

no cellular matrix = no differentiation.

Collagen based diseases?

osteogenesis - fragile bones dwarfism hyperflexibility, fibrosis alpert syndrome is non fibrillar

gap-junction intercellular communication

passage of low weight molecules

how do blood clots form?

platelets adhere to one another through fibrinogen bridges that bind to the platelet-integrins.

Cell wall function and composition?

protection against pathogens and osmotic stress, cellulose into microfibrils give the rigidity of the wall. contains hemicelluloses, pectins, and proteins. arise as a cell plate, the walls of growing cells are primary walls, mature walls are secondary walls.

Proteoglycans ?

protein polysaccharide complex with a core protein attached to GAGS. repeating disaccharide structure, negative GAGs attract lots of cations cross linked into large matrix by hyaluronic acid. they resist crushing forces, provide binding sites for growth hormones, regulate small signaling molecules in developing embryo.

Occludins

proteins found in tight junctions, claudins form the major structure of tight junctions.

function of the ECM?

regulatory role in determining shape and activities of the cell

what is a focal adhesion

site where cells adhere to their substratum and send signals to the cell interior.

gap junctions

sites between animal cells for intercellular communication integration of activities of individual cells into a functional unit. made of connexin, or connexon complex. 6 subunits

Tight junctions?

specialized contacts between epithelial cells. located at very apical end of the junctional complex, serving as a barrier to free diffusion of water and solutes. some an be specific to ions. formed in the blood brain barrier

what is transmembrane signaling

transfer of information across a membrane. integrins and cadherins = from the extracellular to the cytoplasm.