Cell adhesion and communication Flashcards
What do unicellular organisms there to ?
Surfaces or food
- no permanent connection with other cells even tho in colonies
What is planktonic and sessile?
Planktonic = freely exist in medium Sessile = attached to surface/ biofilm e.g agar
What is the extracellular matrix?
- material produced by cells and secreted into surrounding medium
- non- cellular
- arthropods produce chitin
- role in tissue development, function and disease
What are the mechanical roles of the ECM?
tensile + compressive strength
Elasticity
What are the protection roles of Ecm ?
buffer from extracellular change (pH)
Retention of water
What are the organisational roles of ECM?
bind growth factors and interact with cell-surface receptors
Describe connective tissue features
low cell density abundent in ECM ECM load bearing Cell attachments to ECM = force transmission in bones and tendons
Describe epithelial tissue features
closely bound into epithelial sheets
Gut lining and skin epidermis
How does specialisation occur?
highly mineralised in bone + teeth
Transparent in cornea
Elastin in tendons
Liquid in blood plasma
Describe the structure of cellulose
Glucose polymer
1-4 linkage
cellulose strands for in cell mem via cellulose synthase rosettes
Describe the structure of hemicellulose
cross link cellulose microfibrils
backbone = glucose residues (glycosylated)
What contributes to the jell like structure of the matrix?
pectin polysaccharides
What regulates the fluidity of the ECM?
calcium abundance - more ca - more cross links - stiffer
Methylation prevents crosslinks - more fluid
What does pectin methylesterase (PME) do?
Demethylase pectin via ca++ bridges
Why are bacterial ECM different?
its a capsule composed of high molecular weight polysaccharides