Chapter 19: Cell Junctions and Extracellular Matrix Flashcards
What are 2 tissues essential to effective cell binding?
- Epithelial tissue
- Connective tisse
What 2 things do
epithelial tissues do to structurally support cells?
- Transmits cell stresses (via cytoskeletal membranes)
- Anchors cells to eachother + the basal membrane
How does connective tissue aid in the structural integrity of cells?
ECM directly bears mechanical stressors (tension/compression)
What are 4 types of junctions typically found in vertebrate epithelium?
- Tight junctions
- Cell-to-cell anchors
- Gap junctions
- Cell-matrix anchoring junctions
These connections gives space between cells with the same integrity of a plasma membrane; run along the entire width of each cell
Tight junctions
What are the two types of cell-to-cell anchors?
- Desmosomes
- Adherens junctions
These cellular connections allow for quick small molecule transport between two cells
Gap junctions
What are two types of cell-matrix anchoring junctions?
- Hemidesmosomes
- Actin-linked junctions
What proteins enforce the structure of tight junctions?
- Claudin (critical)
- Occludin
These types of anchoring junctions connect cells to other cells; consist of adherins and desmosomes
Cell-to-cell cadherin
This type of anchoring junction connects cells to the ECM; consists of actin-based anchors and hemidesmosomes
Cell-to-matrix (integrin)
This type of cell junctions mediate the passage chemical and electrical signals
Communication junctions
What are the 3 types of communication junctions?
- Gap junctions
- Chemical synapses
- Plasmodesmata
These are channels held together by connexons that connect two different cells by allowing the passage of small molecules between them
Gap junctions
About how wide is the channel of a gap junction?
1.4 nm
What problem of plant cells does the plasmodesmata aim to combat?
Cell communication between thick cell walls
This is the thin tube that connects the smooth ERs of two different plant cells through their cell walls
Desmotube
What ion plays an integral role in the synthesis and structure of cadherin proteins?
Ca2+
What happens to cadherin proteins without adequate amounts of Ca2+
Floppy, not structurally sound, incapable of interacting with other cadherins
How does trypsan solution allow for the easy lifting of cells in cell culture?
Cleaves proteins and chelates Ca2+ ions
This is a triple stranded, super-coiled alpha helix that is intergral to cellular structure
Collagen
Fibrilar collagen is synthesized by what cells?
Fibroblasts
What are the 3 steps of fibrocollagen/collagen formation?
- Procollagen triple helix formed (in ER & Golgi)
- Procollagen cleaved and separated
- Resulting collagen aggregates into fibers
What is the normal repeat of collagen?
Glycine-proline-hydroxyproline
What is the purpose of hydroxyproline in collagen fibers?
Stabilizes collagen fibers (allows for supercoiled helix to form)
A severe lack of vitamin C (scurvy) does what to collagen?
Inhibits hydroxyproline formation (becomes Gly-proline-proline); looses stability and falls apart
What are the symptoms of scurvy?
Tooth loss, slow wound healing, fragile blood vessels, bone pain, heart failure
