Forming Tissues Flashcards
(18 cards)
How do tight junctions work
Neighbouring cells connected via cell surface proteins called Claudins &occludins, which are then connected to actin filaments for strength. Actin and these proteins r connected by ZO complex.
Explain role of desmosome
Cell surface molecules called cadherins form connections between similar cells
Desmosomes connect cells through intermediate filaments
Anchor proteins needed to connect Cadherin molecules to cytoskeleton
Similarities&difference between desmosomes and tight junctions
S-Anchor proteins needed to connect cadherin molecules to cytoskeleton
D- wider gap in desmosomes
Similarity& differences between desmosomes and adherens junction
S- use cadherins and anchor proteins
D- adherens junction connect to actin filament
How do cells attach to ECM
Cell surface molecules called integrins which act as matrix receptors
And transmit signals into the cell to respond to its surroundings
Role of ECM
mechanical &. Biochemical support for tissues
Form basement membranes- thin sheets of ECM at the base of tissues
Component of ECM
Collagen
Fibronectin
Proteoglycan ( polysaccharide protein and carbohydrate)
Role of proteoglycan
Found in cell surface and ECM
lubricate ECM and modify activity and stability of other proteins in ECM
Describe structure of fibronectin
Glycoprotein with many binding sites for multiple ECM proteins as well as for integrins
Describe structure of integrins
alpha and beta chain and different combinations of these allow recognition of wide range of ECM components
Change shape into an open conformation when bind to ECM
How does integrin attach to ECM
Cytoplasmic tail of Integrin connects to actin cytoskeleton through anchor and adaptor proteins called adhesion complex
Apart from adhesion complexes, describe another way cells attach to ECM
attach to basement membranes through hemodesmosomes which connect ECM to intermediate filaments in the cell
This link goes through integrin molecules
Role of fibroblast
Important in maintaining the ECM
Advantages of multicellularity
Improved acquisition of resources
Increases resistance to stresses
Protection from predation
Opportunity for cell differentiation and specialisation a,omg different cells
Disadvantages of multicellularity
Energetic costs
Physical limitations of reduced freedom of movement
Describe biofilm formation
Biofilm - multicellular aggregate
Cells attach to surface and join to other cells which form micro colonies which expand in size to form biofilm. Release individual cells for dispersal
How does social amoeba thrive
Alternate between single felled and multicellular
When food is scarce cells aggregate to aid dispersal
What is clinal multicellularity
All cells in organism have same DNA
