Ch.19-Cell Junctions, Cell adhesion, and the extracellular matrix Flashcards
1A. What is the function of Tight Junctions
= prevent molecules from passing between cells
1B. What is the function of Gap junctions
= allow small molecules (<2500 Daltons) to pass
1C. What is the function of Anchoring junctions
= keep cell attached to each other or to extracellular matrix
1D. What is the function of Occluding junctions
= type of tight junction
2A. What are occluding junctions?
= type of tight junction
2B. What are anchoring junctions?
= keep cell attached to each other or to extracellular matrix
2C. What are communicating junctions?
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- Describe the role of tight junctions in intestinal epithelial cells.
- It prevents molecules from passing between cells
- It prevents membrane proteins from moving to membrane at the other end of the cell
- What proteins are present in tight junctions?
Claudins and occludins bind to each other to form tight junctions
- What is the difference between adherense junctions and desmosomes?
- Adherense junctions:
= with adjacent actin cells - Desmosomes:
= with adjacent intermediate filaments
- What is the difference between hemidesmosomes and focal adhesions?
- Hemidesmosomes:
= when intermediate filaments are attached to extracellular matrix - Focal Adhesions:
= when actin cells are attached to extracellular matrix
- What is the difference between hemidesmosomes and desmosomes?
- Hemidesmosomes:
= when intermediate filaments are attached to extracellular matrix
-Desmosomes:
= with adjacent intermediate filaments
- What do integrins do?
give 2 examples
= Link extracellular matrix to cytoskeleton
- Ex: Hemidesmosomes, focal adhesion points
- What do cadherins do?
give 2 examples
= Proteins that form anchoring junctions between cells
- Ex: Adherence junction, desmosome
- How does Ca2+ affect cadherin structure?
- Calcium is need, cadherins bind calcium-required to make protein rigid.
- If you have low calcium, no junction cells are attached to each other
- What kind of molecules can pass through gap junctions?
- Small molecules (<5000 Daltons)
- Water soluble molecules
- Describe Gap Junctions
= are made out of connexons (6 connexins stacked on top of each other makes up a gap junction)
- can be open or closed
- they allow for molecules less than 5,000 Daltons in size to pass
- What are connexins?
= Protein that forms the gap junction
- What does it mean that the permeability of gap junctions can be regulated? Give an example of a molecule that can regulate gap junction permeability.
Gap junctions can be regulate through voltage gated, requires a signal to open junction, regulate the size of the gap junction, has to be water soluble to pass
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- How can cells self-organize based on the type of cadherins they are expressing?
- Cadherins will sort themselves out by either having two different cadherin types by only binding to self
- they can also sort out by binding to different amounts of type of cadherin expressed
- this is an important process in development
- What does the extracellular matrix consist of?
- proteoglycans
- water
- minerals
- fibrous proteins
- What is a proteoglycan? Describe the different parts of a proteoglycan.
(look up on study blue too)
= A core protein that has glycosaminoglycans attached to it (has them attached through a link tetrasaccharide)
18A. What are glycosaminoglycans?
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18B. Describe some aspects of the glycosaminoglycans structure
- are abundant in extra cellular matrix
- are large carbohydrates that consists of repeating disaccharides
- has an amine group associated with it,
- are attached to a core protein
19A. What do fibroblasts do?
= secrete the extra cellular matrix
19B. Where would you find fibroblasts cells?
= within connective tissue
- What is hyaluronan?
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- What is collagen?
= Collagen is an abundant protein in extra cellular matrix
- Describe the structure of collagen.
- 3 amino acid chain wrapped around each other
- each chain is a helix
- 3 amino acids repeat x-y-glycine
- What is elastin?
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- What is fibronectin?
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- What is the basal lamina?
= It is a 2D sheet that is made up out of proteins, attached to a cell cytoskeleton on the basal side via integrins
- cells can control if intergrins are attached to the basal lamina (controlled through signaling molecules)
- sometimes during development cells must be attached to the basal lamina to prevent apoptosis
26.What is the basal lamina made of?
- intergrins
- intermediate filaments
- collagen
- etc
- Describe the functions of the basal lamina.
= Acts as a barrier so that cells will not be able to cross through easily (cancerous cells)
- is involved in cell regeneration (can act as a template of the original structure for regrowth)
- structure that filatures blood in the kidney
