Unit 2 Chapter 8: Cell-Cell Interactions Flashcards
What is the primary cell wall
- forms when plant cells first form
- defines shape
- initial fibre composite
- fibrous component = long strands of cellulose, crosslinked by other filaments and bundled into cable-like microfibrils
- space between microfibrils is filled with gelatinous pectins, which attract and store lots of H2O to make cell wall moist
What is turgor pressure
pressure exerted by the inflated plasma membrane caused by an inward flow of water due to osmosis, leads to cell growth
What is the secondary cell wall
- made when cells stop growing
- inside primary cell wall
- structure varies, could be lignin, cellulose,etc.
What is the extracellular matrix
- found in animal cells
- fibre composite
- contains much more protein than a cell wall
- dominated by collagen
- matrix that surrounds collagen is made of gel forming polysaccharides with a protein core
- most components synthesized in ER-golgie-secreted
What is collagen
3 polypeptide chains that wind around eachother
Why is the link between the cytoskeleton and extracellular matrix critical
- keeps cells in place, helps adjacent cells adhere via their common connection
- if the link is broken cancer can form
What are focal adhesions
adhesion sites between actin filaments in the cell and the extracellular matrix
What are integrins
transmembrane proteins that bind to actin filaments in the cytoskeleton which also bind to proteins in ECM called fibronectins which bind to collagen
What is a tight junction
cell-cell attachment made of special proteins in the plasma membranes of adjacent cells
- looks like quilting where proteins act as stitches
- form a water tight seal
- found in epithelial cells in stomach and intestines
- open and close in response to environmental conditions
What are desmosomes
- particularly common in epithelial and muscle cells
- bind the cytoskeletons of adjacent cells
- contain proteins that bind to eachother and to larger proteins that anchor inter.filaments in the cytoskeletons of the 2 cells
What is cell recognition
one cell specifically binds to another cell of a certain type
What is cell-cell adhesion
cells stably bind to eachother
What is selective adhesion
cells adhere to other cells of the same tissue type (only one species and one cell type)
What are caherins
the attachment molecules in desmosomes
What does the presence of holes or gaps do
allows adjacent plant cells to retain their own organelles, proteins, nucleic acids but communicate by sharing ions and small molecules in their cytoplasm
