unit 5 Flashcards
What are tissues composed of?
Cells and the ECM
What is the cell wall (in plants) made of?
Cellulose and other polysacharrides
What do cellulose microfibrils do?
Confer tensil strentg
How do microtubules function in cell walls?
They help to direct and position cellulose in the cell wall
What mainly makes up connective tissues?
The extracellular matrix
What are all cell types differentiated from
fibroblasts
What are the two types of ECM
Basal lamina and connective tissue
What is the basal lamina and what types of tissues is it commonly found in?
An ECM type that forms a sheet of proteins; often in epithelial tissues
What is connective tissue and where is often found?
An ECM type that is a dense packing of ECM proteins. Found in dermis, bones, tendons, etc.
What are the 3 classes of ECM?
Proteoglycans, collagen, and multi-adhesive matrix proteins
What are some functions of the ECM?
Provide structure, important for tissue development, cell migration, sequestering growth factors
What is the function of proteoglycans? How are they composed?
Cell-ECM interactions and signaling; glycoproteins containing covalently linked polysaccharide chins
What is the function of collagen? What is its composition?
Tissue strength; cross linked fibers and sheets
What is the main difference in function between collagen and glycosaminoglycans
Collagen provides tensile strength, while glycosaminoglycans (which form proteoglycans) act as spacefillers and resist compression
How are collage fibrils organized?
Triple stranded collagen molecules forms collagen fibrils.
What path does collagen take during its synthesis?
Three singlular collagen polypeptide chains wind in the ER to create a procollagen molecule. They then enter the golgi apparatus and enter the extracellular space via exocytosis, where they are processed (terminal polypeptides removed), and the collegen molecules are assembled.
What are the two ways that cells can interact with the ECM?
Focal adhesions and hemidesmosomes
What are focal adhesions?
Cluster of integrins linked to actin