EXTRACELLULAR MATRIX Flashcards
why is it helpful for bacteria to have a cell wall?
bacteria can provide structural integrity, shape, and resistance
describe peptidoglycan
made of sugars and amino acids w/ cross linked peptide chains; create a crystal lattice structure = support and rigidity
how does penicillin effect peptidoglycan?
it inhibits the transpeptidase that is responsible for cross-linking peptidoglycan = creates poor wall support
why do we need to be concerned about antibiotic overuse?
overusing antibiotics, like penicillin, can harm cells that do not have the bacteria structure; cells can also build resistance to antibiotics and will no longer be impacted by them (this is bad!!)
how do plant and bacteria cell walls differ?
plant cell walls have cellulose to provide support where bacteria have peptidoglycan
cellulose = beta glucose monomers that will leave cell to create microfibrils - these create interactions w/ sugars = support!
what do connective tissue, bone, tendons, and ligaments have in common?
all are surrounded by basal lamina: a layer of the ECM that’s secreted by epithelial cells
what is the general structure of the extracellular matrix?
the ecm is a non-cellular aspect within tissues to form a “scaffolding” of sorts - fills in empty space
primarily made of glycoproteins and collagen; allows for structural and biochemical support
what are collagen fibers and elastins?
connective tissue made of triple helix proteins; secreted by fibroblasts
what role do collagen and elastins play in the ECM?
work together to allow elasticity, contractility, and flexibility
what are GAGs and what role do they play?
glycosaminoglycans; secrete a polysaccharide gel; maintain skin’s health and may be a part of cell signaling
what are proteoglycans and what role do they play?
made of GAGs covalently attached to proteins; assist in proliferation
what would happen if a cell couldn’t produce laminin and fibronectin?
these are adhesion proteins; no production of these = no connections or cell assembly
describe the relationship between integrins, focal adhesions, and hemidesmosomes
integrins - transmembrane proteins that bind to ligands and mediate adhesion
focal adhesions - structures that integrins link cytoskeleton to ecm with
hemidesmosomes - anchoring junctions that link epithelial cells to basement membrane
what are adhesion junctions?
multi-protein complex that connect cells at cell-cell and cell-matrix junctions
consist of selectins, integrins, Ig superfamily, and cadherins (loss of cadherins can lead to cancer)
what are tight junctions?
separate cell membrane into basal and apical domains by forming seals to prevent molecules from passing between epithelial cells
network of proteins; not good at holding cells together but work with adhesion proteins and desmosomes to create junctional complexes
what are gap junctions?
channels between two cells and allow molecule exchange
made via connection of two connexons - each has 6 subunits
disease can occur if mutation in genes for gap jxn
what are plasmodesmata?
adhesion between plant cells mediated by cell wall components
adjacent cells will have continuous plasma membrane
what is a junctional complex?
complex of tight junctions, anchoring/adhesion proteins, and desmosomes that connect cells to each other/to ECM
