ECM Flashcards
Lamina and fibronectins are found in soluble and insoluble forms. True or false. Why?
False. Fibroconectins are found in both forms, but lamina is only found in insoluble forms.
Tight junctions are composed of networks of
Fibral networks that work being epithelial cells and endothelial cells
The major structural protein of the extra cellular matrix of animal cells is
Collagen
What is the purpose of GAP junctions?
They make it easier for small molecules to be transfered between adjacent cells.
Mutations in Laminins and fibroconectins cause epidermolysis bullosa. True or false? Why?
False. It is a mutation in the collagen, from K5 and K14
Despite the fact that they possess no intrinsic signaling ability, integrins are still considered signaling receptors. How is this possible?
Affinity and avidity, they are the most abundant and most critical for multicellularity to exist. They control both cell binding to ECM proteins and intracellular responses after adhesion, done with adaptor proteins linking them to signaling proteins.
Tissue cells are connected to the extra cellular matrix by receptors that bind to the adhesive protein
Laminin
Laminins and fibroconectins contain triple helical domains. True or false.
True. Lamina provide an adhesive substrate for cells.
Laminins and fibroconectins contain triple helical domains. True or false
True. Collagen is triple but the others are double.
What are GAP junctions?
They are protein structures that make it easy to directly transfer small molecules between adjacent molecules. They are found in most animal cells.
Collagen exists as a coiled protein due to the presence of three repeating amino
Acids: __,__,__
Glycine, hydroxyproline, and proline
Laminins are found primarily in the basal lámina. True or false
True
Adjacent plant cells are connected via ________ to equalize the ionic concentrations of their cytosol.
Plasmodesmata
Give a definition for the extra cellular matrix
Collection of insoluble, flexible, fibrous proteins and highly charged proteoglycan that lies outside the cellular membrane. Made by the cells themselves.
What are the molecular connexons making by GAP junctions?
They have two halves, and the two halves are called connexons and hemichannels. They are made of 6 protein subunits called connexons.
Name the location, function, and composition of hemidesmosomes in epithelial cells (6 points)
-They provide structural stability to epithelial sheets
-Found on basal surface of epithelial
cells
-They link the ECM to the intermediate filament network via transport receptors.
-contain transmembrane proteins
-They are linked to the intermediate filament in the cytoplasm
-They do NOT bind directly to the ECM, but indirectly, through integrin and lamina
Explain the difference between avidity and affinity modulation of integrin receptor binding
Avidity: varying the clustering of receptors.
Affinity: varies the binding strength of individual receptors.
What are hemidesmosomes? Name 5 points
-They provide structural stability to epithelial sheets
-They are found on the basal surface of epithelial cells, where they link the ECM to the intermediate filament network via transport receptors
-Contain transmembrane proteins (integrins, which means they can also initiate intracellular signaling pathways)
-they are linked to intermediate filament in the cytoplasm
-they do NOT bind to the ECM directly, but INDIRECTLY, through integrin and lamina.
Recall the structure and function of integrin receptors
-they are two alpha and beta subunits
-Function: they act as a receptor controlling cell binding and intracellular responses after adhering
-They also function as a hook giving information about surroundings (critical for multicellularity)
What makes elastin so elastic? Name two reasons
-the strength of elastic fibers arises from covalent crosslinks formed between lysine side chains in adjacent elastin monomers
-The sequence goes hydrophilic-hydrophobic-hydrophilic, which causes them to repel each other. This is when they are resting. As it elongates, it forces the subunits to come close together, and the hydrophobic/hydrophilic regions come closer together, and after the stress is released, the force spontaneously takes back its initial length.
Name the location, function, and composition of adheren junctions in epithelial cells (6 points)
-link neighboring cells
-Contain transmembrane cadherin receptors
-They are a link to actin filaments
-Are involved in binding with actin filaments.
-They help Maintain two cells together
-they form strong adhesions to prevent too much passage between cells.
