Chapter 7 Flashcards
Do cells interact with the extracellular environment?
Yes
What is the glycolyx?
Carbohydrate projections on outer surface of the plasma membrane
Roles of the glycolyx?
- mediator of cell-cell and cell-substratum interactions
- mechanical projection
- barrier to molecular movement toward plasma membrane
- regulatory factor binding site
ECM protein texture:
Fibrous
What is the best to find extra cellular matrices?
The basement membrane
What does the basement membrane surround?
Muscles, nerves, and fat cells 
What are collagens?
A family of fibrous glycol proteins known for their high tensile strength the function exclusively as part of the extra cellular matrix
What is the most abundant protein in the human body?
Collagen
A collagen molecule is made up of what?
Triple helix of three helical alpha chains, known as trimers
What is collagen produced by?
Fibroblasts, smooth muscle, and epithelial cells 
What is the corneal stroma?
Layers of collagen fibres of uniform diameter and spacing arranged at right angles
Define: Proteoglycans
Protein – polysaccharide complex, with a core protein attached to glycosaminoglycans
Where are proteoglycans common?
In basement membranes and cartilage
What is fibronectin?
It binds to cell receptors to attach cell to the ECM, used for cell adhesion and shape determination
What is laminin?
It can influence the cells potential for migration, growth, and differentiation. Role in development of neuronal outgrowth
What are integrins?
Family of membrane proteins unique to animals, in cells not the ECM
What are integrins composed of?
Two membrane spanning polypeptide chains, an alpha and a beta chain
Changes in integrins are driven by what?
Divalent metal ions
What are the two major activities of integrins?
- Adhesion of cells to ECM or two other cells
- Transmission of signals between external environment and cell interior
Intracellularly, integrins binds to what?
Ligands like talin (Inside out signalling)
What are outside in signals?
Different integrins find different ECM components, can induce confirmational change in Talin
What is the function of outside in signals?
Can influence cell differentiation, motility, growth, and cell survival
What is focal adhesion?
Cultured cells are anchored to surface of the dish only at scattered, discrete sites
Focal adhesion function:
Play a key role in cell and heating and locomotion
What kind of structures are focal adhesions?
Dynamic structures
What are hemidesmosomes?
Sell to ECM attachment in vivo, scene at basil surface of epithelial cells, anchored to underlying basement membrane
How are keratin filaments linked to ECM?
By integrins
What is cell to cell adhesion mediated by?
- Selectins
- Members of IGSF (Immunoglobin super family)
- Members of integrin family
- Cadherins
What are selectins?
A family of membrane glycol proteins that bind to specific oligoaccharides
Selectin structure
Small cytoplasmic segment, a single membrane spanning domain, and large extra cellular
What are selectins present on?
Platelets, and Endothelial cells, leukocytes
Selects signal what?
Cell growth, migration, differentiation, and survival
What are cadherins?
Glycoprotein family member, typically join cells of similar type to one another
Where are cadherins found?
Adheren junctions and desmosomes
What are tight junctions?
Occur between neighbouring epithelial cells and seals extra cellular space
What is the function of tight junctions?
Prevents solute distribution where different soluble concentrations are in adjacent compartments
What are gap junctions?
Sites between animal cells that are specialized for intercellular communication
Do plasma membranes make a direct contact at the gap junction?
No
What are gap junctions composed of?
Several integral membrane proteins and organized into multi subunit complexes
What is a major role of cell to cell adhesion in humans?
Inflammation
