PSU BMB 252 EXAM 3 QUESTIONS AND ANSWERS
What is the ECM? - CORRECT ANSWER✅✅✅Extracellular matrix
a network of proteins and polysaccharide chains that are secreted by cells
What are the two forms of the ECM? What are they each? - CORRECT ANSWER✅✅✅ECM of
connective tissue= fibrous polymers like collagen
Basal Lamina= flexible, thin mat of specialized ECM that underlies epithelial cell sheets and tubes
What are the two ways that cells are attached in tissue? - CORRECT ANSWER✅✅✅either to the
basal lamina or to the ECM and to each other
What are the 4 main types of junctions? - CORRECT ANSWER✅✅✅1. Tight junction
2. Cell-cell anchoring junction (adherens and desmosomes)
3. Gap junction
4. Cell-matrix anchoring junction (hemidesmosome and actin-linked cell-matrix junction)
What are cadherins? What are they made of? What do they depend on? - CORRECT ANSWER✅✅✅-
anchoring junction that links cells together
-transmembrane protein
-depend on Ca
cadherens = ca2+ + adherins
What are integrins? - CORRECT ANSWER✅✅✅anchoring junction that links cells to the ECM
What are adherins junctions? - CORRECT ANSWER✅✅✅cell-cell anchoring junction that links actin
filaments
What are desmosomes? - CORRECT ANSWER✅✅✅cell-cell anchoring junction that links
intermediate filaments
,What filament forms a layer close to the cell surface? - CORRECT ANSWER✅✅✅actin
What are the two cell-matrix anchoring junctions? - CORRECT ANSWER✅✅✅actin-linked cell-matrix
adhesions (focal adhesions) and hemidesmosomes
What are focal adhesions? - CORRECT ANSWER✅✅✅link actin filaments to the ECM
What are hemidesmosomes? - CORRECT ANSWER✅✅✅Link intermediate filaments to the ECM
What are the two types of cadherins and what are the differences? - CORRECT
ANSWER✅✅✅classical= named according to tissue they were first found
non-classical- more than 50 alone in brain
Where are each of these cadherins?
N-cadherin
P-cadherin
E-cadherin - CORRECT ANSWER✅✅✅N-cadherin --> nerve
P-cadherin--> placenta, epidermis
E-cadherin---> epithelial
What is the difference between homophilic and heterophilic binding? - CORRECT
ANSWER✅✅✅Homophilic binding happens between molecules that are closely related or the same,
whereas heterophilic binding is between two totally different molecules
What happens to cadherin in the absence of Ca? - CORRECT ANSWER✅✅✅the cadherin molecules
become floppy and interaction fails
How are cadherin molecules arranged? What does it resemble? - CORRECT ANSWER✅✅✅like
velcro, arranged in parallel fashion
, What allows dissociated cells or migrating cells to sort out and reassemble into organized tissues? -
CORRECT ANSWER✅✅✅selective cell adhesion
Where do most cancers originate from? - CORRECT ANSWER✅✅✅epithelium
If there is a mutation in E-cadherin, what does that promote? - CORRECT ANSWER✅✅✅metastatic
cancer
What are Beta-catenins? What do they do? Where are they found? - CORRECT ANSWER✅✅✅a dual
function protein that helps with cell-cell anchoring and also with gene transcription and is found in the
Wnt/B-catenin pathway
it indirectly links classical cadherins to actin filaments
What happens when there is tension and cells are pulling away from each other? What happens with
adherens junctions and actin? - CORRECT ANSWER✅✅✅they respond to these forces and alpha-
catenin stretches which opens up a domain for vinculin binding, this leads to the recruitment of more
actin
What is the adhesion belt? - CORRECT ANSWER✅✅✅a continuous linkage of actin between cells
is important for folding of epithelial sheet to make tubes, helps to regulate cell structure
Where is keratin found? Where is desmin found? - CORRECT ANSWER✅✅✅keratin found in most
epithelial cells
desmin filaments in heart muscle
What does cadherin name come from? - CORRECT ANSWER✅✅✅CA-lcium D-ependent = cad
What is the shape of a desmosome? - CORRECT ANSWER✅✅✅its a small button like structure.
What is the ECM? - CORRECT ANSWER✅✅✅Extracellular matrix
a network of proteins and polysaccharide chains that are secreted by cells
What are the two forms of the ECM? What are they each? - CORRECT ANSWER✅✅✅ECM of
connective tissue= fibrous polymers like collagen
Basal Lamina= flexible, thin mat of specialized ECM that underlies epithelial cell sheets and tubes
What are the two ways that cells are attached in tissue? - CORRECT ANSWER✅✅✅either to the
basal lamina or to the ECM and to each other
What are the 4 main types of junctions? - CORRECT ANSWER✅✅✅1. Tight junction
2. Cell-cell anchoring junction (adherens and desmosomes)
3. Gap junction
4. Cell-matrix anchoring junction (hemidesmosome and actin-linked cell-matrix junction)
What are cadherins? What are they made of? What do they depend on? - CORRECT ANSWER✅✅✅-
anchoring junction that links cells together
-transmembrane protein
-depend on Ca
cadherens = ca2+ + adherins
What are integrins? - CORRECT ANSWER✅✅✅anchoring junction that links cells to the ECM
What are adherins junctions? - CORRECT ANSWER✅✅✅cell-cell anchoring junction that links actin
filaments
What are desmosomes? - CORRECT ANSWER✅✅✅cell-cell anchoring junction that links
intermediate filaments
,What filament forms a layer close to the cell surface? - CORRECT ANSWER✅✅✅actin
What are the two cell-matrix anchoring junctions? - CORRECT ANSWER✅✅✅actin-linked cell-matrix
adhesions (focal adhesions) and hemidesmosomes
What are focal adhesions? - CORRECT ANSWER✅✅✅link actin filaments to the ECM
What are hemidesmosomes? - CORRECT ANSWER✅✅✅Link intermediate filaments to the ECM
What are the two types of cadherins and what are the differences? - CORRECT
ANSWER✅✅✅classical= named according to tissue they were first found
non-classical- more than 50 alone in brain
Where are each of these cadherins?
N-cadherin
P-cadherin
E-cadherin - CORRECT ANSWER✅✅✅N-cadherin --> nerve
P-cadherin--> placenta, epidermis
E-cadherin---> epithelial
What is the difference between homophilic and heterophilic binding? - CORRECT
ANSWER✅✅✅Homophilic binding happens between molecules that are closely related or the same,
whereas heterophilic binding is between two totally different molecules
What happens to cadherin in the absence of Ca? - CORRECT ANSWER✅✅✅the cadherin molecules
become floppy and interaction fails
How are cadherin molecules arranged? What does it resemble? - CORRECT ANSWER✅✅✅like
velcro, arranged in parallel fashion
, What allows dissociated cells or migrating cells to sort out and reassemble into organized tissues? -
CORRECT ANSWER✅✅✅selective cell adhesion
Where do most cancers originate from? - CORRECT ANSWER✅✅✅epithelium
If there is a mutation in E-cadherin, what does that promote? - CORRECT ANSWER✅✅✅metastatic
cancer
What are Beta-catenins? What do they do? Where are they found? - CORRECT ANSWER✅✅✅a dual
function protein that helps with cell-cell anchoring and also with gene transcription and is found in the
Wnt/B-catenin pathway
it indirectly links classical cadherins to actin filaments
What happens when there is tension and cells are pulling away from each other? What happens with
adherens junctions and actin? - CORRECT ANSWER✅✅✅they respond to these forces and alpha-
catenin stretches which opens up a domain for vinculin binding, this leads to the recruitment of more
actin
What is the adhesion belt? - CORRECT ANSWER✅✅✅a continuous linkage of actin between cells
is important for folding of epithelial sheet to make tubes, helps to regulate cell structure
Where is keratin found? Where is desmin found? - CORRECT ANSWER✅✅✅keratin found in most
epithelial cells
desmin filaments in heart muscle
What does cadherin name come from? - CORRECT ANSWER✅✅✅CA-lcium D-ependent = cad
What is the shape of a desmosome? - CORRECT ANSWER✅✅✅its a small button like structure.
