Cell-to-cell interactions Flashcards
What are the 3 basic features in multicellular animals?
- Formation of diverse kinds of tissue
- Cells being able to communicate w/ each other
- Cells having markers of individual identity
What kind of proteins do the 3 basic features involve?
-Membrane proteins & proteins secreted by cells
What are the 7 kinds of connections between cells?
- Surface markers
- Septate junctions & tight junctions
- Desmosome (adhesive junction)
- Adherens junction (adhesive junction)
- Hemidesmosome/ focal adhesion (adhesive junction)
- Gap Junction (communicating junction/ Animals)
- Plasmodesmata (communicating junction/ Plants)
What are the 3 types of Adhesive Junctions?
- Desmosomes
- Adherens Junction
- Heridesmosome/ Focal adhesion
What are the 2 types of Communicating Junctions?
- Gap junction
- Plasmodesmata
What functions to mark the surfaces of cells?
-A key set of genes
When cells of the same tissue recognize each other, what do they do?
-They respond by forming connections between their surfaces to better coordinate their functions
What are Glycolipids?
- They’re surface markers for tissue-specific cells
- They’re lipids w/ carbohydrate heads
What blood types are the Glycolipids on the surface of RBD responsible for?
-A,B, and O blood types
What is an example of the function of the cell-surface markers?
-The recognition of “self” & “non-self” by the immune system= vital for multicellular organisms to defend themselves against invaders
What is Major Histocompatibility Complex (MHC)?
-Proteins= makers that vertebrates use to distinguish self from non-self
What is vital for a tissue to maintain its characteristic architecture?
-Cell junctions
What are Adhesive Junctions & where are they found?
- They mechanically attach the cytoskeleton of a cell with the cytoskeleton of other cells or to the extracellular matrix
- They’re found in tissues subject to mechanical stress= muscle & skin epithelium
What are Adherens Junctions & where are they found?
- They’re based on the protein Cadherin
- They’re found in animals ranging from jellyfish to vertebrates
What is Cadherin & how does it help adherens junctions?
- A protein that is Ca2+ dependent adhesion molecule w/ very wide phlyogenetic distribution
- It’s a single-pass transmembrane protein w/ extracellular domain of a cadherin in an adjacent cell to join cells together
How does Cadherin interact on the cytoplasmic side?
-They interact indirectly through other proteins w/ actin to form flexible connections between cells
What are Desmosomes?
- They are a cadherin-based junction unique to vertebrates
- They join adjacent cells= support tissues against mechanical stress
What 2 types of Cadherin do desmosomes have & what do they do?
-Desmocollin & Desmoglein= interact w/ intermediate filaments of cytoskeletons INSTEAD of actin
What are Hemidesmosomes & Focal adhesions?
- They connect cells to the basil lamina or other ECM
- Also connect the cytoskeleton of cells= actin filaments at focal adhesions & intermediate filaments at hemidesmosomes
What are the proteins that interact w/ the ECM in hemidesmosomes & focal adhesions?
-Integrins= Cell-surface receptors that bind to a protein component of the ECM
What are Septate Junctions?
-They’re found in both invertebrates & vertebrates & form a barrier that can seal off a sheet of cells
What are Tight Junctions?
- They’re unique to vertebrates & contain proteins called Claudins= abilty to occulde/block subtances from passing between cells
- IS A BRICK WALL
What are Communicating Junctions?
- Allow communication between cells by diffusion though small openings
- They permit small molcules or ions to pass from one cell to another
What are Gap Junctions?
- They’re found in both invertebrates & vertebrates (in invertebrates they’re formed by protein pannexins while the vertebrates= connexons)
- Provide passageways large enough to permit small substances (amino acids, simple sugars) to pass from one cell to the next but small enough to prevent passage from bigger molecules (proteins)
