Lecture 7

Question 1

What holds cells together?

Answer 1

Cell-cell adhesion molecules
Extracellular matrix proteins
Internal-external scaffolding
Close proximity

Question 2

Adherens junctions

Answer 2

Tissue stabilising factor+ acts as barrier
Formed from intracellular actin filaments
Linked to E-cadherin proteins that cross the intercellular space

Question 3

What do desmosomes do?

Answer 3

Provides mechanical strength and further cell-cell stabilising. Strongest one
In skin cells, this is the only cell-to cell adhesion.
Cytokeratin fibres intracellularly, E-cadherins intercellularl

Question 4

Where are gap junctions not found?

Answer 4

Spermatozoa, erythrocytes and motile cells

Question 5

Hemi-desmosome

Answer 5

Found on basal surface and anchors the basal lamina to the connective tissue + prevents loss to external surface.
Intracellular intermediate filaments of cytokeratin
attached to laminin through integrins

Question 6

Focal adhesions

Answer 6

Same function as hemi desmosomes and uses actin filament as intermediates instead of cytokeratin.Uses integrins aswell. Attaches to fibronectin instead of lamina.When bound to fibronectin, conformational change results in binding
to collagen fibres

Question 7

What do gap junctions do?

Answer 7

Function - to quickly communicate changes in intercellular molecular composition e.g. electrolyte+ energy changes
Allows free movement of small molecules from one cell to another e.g. ions, most sugars, amino acids
Consist of cylinders of proteins (connexins) arranged in a hexagonal
pattern that open and close (ATP)

Question 8

Integrins

Answer 8

Alpha-beta diamer