Adhesion & Cell-Cell Interactions

Question 1

How many cell types in the body?

How are they joined

Answer 1

~200 cell types joined in epithelial sheets

Question 2

5 epithelia types

Answer 2

• simple
• stratified
• squamous
• cuboidal
• columnar

Question 3

2 surfaces of epithelial cells

Answer 3

1. basal surface

2. apical surface

Question 4

basal lamina composed of:

Answer 4

type IV collagen, containing laminin

Question 5

5 cell junction types

Answer 5

• tight junctions
• gap junction
• desmosomes
• hemidesmosomes
• adherens junctions

Question 6

what protein is used together with cytoskeleton-linked junctions?

Answer 6

cadherin

Question 7

Tight junctions

Answer 7

prevent solute leakage between cells, maintain osmotic balance and cell polarity

Question 8

Breakdown of tight and adherens junctions linked to:

Answer 8

cancer metastasis

- loss of E-cadherin and ZO-1

Question 9

Adherens junctions

Answer 9

Ca2+ dependent cadherins tethered to actin filaments via catenins
- bundles of actin filaments connecting cells

Question 10

EMT transition

Answer 10

activation of Wnt signalling and increase of beta-catenin activates cancer genes

Question 11

Desmosomes

Answer 11

• join intermediate filaments of cells together
• cadherins tethered to keratins
• keratin bundles cross cytoplasm and are linked to other cells via desmosomes
• provide tensile strength

Question 12

Hemidesmosomes

Answer 12

• intermediate filaments tethered to basal lamina via integrins via plaque linker proteins

Question 13

Gap junctions

Answer 13

• form channels that allow small molecules to pass from cell to cell
• gap filled with transmembrane connexon complexes with inner water filled channels
• can be open or closed in response to extra/intracellular signals

Question 14

Gap junctions is plants called:

Answer 14

Plasmodesmata