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Cell Bio Chapter 17
Junctions & ECM
49
Biology
Undergraduate 4
07/25/2013

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Term
Homophilic CAM junction
Definition
occurs between two cell adhesions of the same type
Term
Heterophilic CAM junctions
Definition
occurs between two cell junctions of different types
Term
Explain the origin of the name of cadherin junction
Definition
Calcium dependent adhesion
Term
What do lectins bind to?
Definition
to the terminal sugar groups of oligosaccharide chains (glycoproteins, proteoglycans)
Term
Why do they call come lectins agglutins?
Definition
Lectins have multiple binding sites
Term
What determines someone's blood group?
Definition
carbohydrate on glycolipids and glycoproteins on the red blood cell
Term
Plasma universal donor
Definition
AB
Term
Plasma universal recipient
Definition
O
Term
RBC universal recipient
Definition
AB
Term
RBC universal donor
Definition
O
Term
three main FUNCTIONAL categories of cell junctions
Definition
1) tight (zonula occludens) (occluding) junctions
2) adhering (zonula adheren, macula adheren) (adhesive) junctions
3) gap (communicating) junctions
Term
Where are zonula occludens?
Definition
just below the apical membrane
form the definition of apical vs. basolateral
Term
two functions of zonula occludens
Definition
1) keep most molecules from entering into the inter membrane space
2) define the apical membrane from the basolateral membrane
Term
Name two types of adhering junctions
Definition
1) zonula adherens
2) macula adherens
Term
Where are the zonula adherens?
Definition
just under the tight junctions
Term
what does zonula mean
Definition
belt-like
Term
what does macula mean
Definition
spot or button
Term
What cytoskeletal element binds to the zonula adherens?
Definition
actin microfilaments
Term
Synonym for macula adherens
Definition
Desmosomes
Term
Where are macula adherens
Definition
scattered all over the lateral surfaces of the cell
Term
what cytoskeletal element interacts with the macula adherens?
Definition
intermediate filaments
Term
what size molecule gets through a gap junction?
Definition
up to about 1,200 Daltons
Term
Name adhesive proteins found in the ECM (4)
Definition
1) fibronectin
2) laminin
3) collagen
4) elastin
Term
name two unusual amino acids in collagen
Definition
1) hydroxylysine
2) hydroxylproline
Term
What is an MMP?
Definition
matrix metalloproteinase
Term
What do MMPs do?
Definition
degrade the ECM, cancer cells use them to invade other cells, inflammatory cells use them to respond to injury
Term
what type of receptor binds to ECM fibers?
Definition
integrins
Term
what type of cell junctions do plants have that animals don't?
Definition
plasmodesmata
Term
How do plasmodesmatas differ from gap junctions?
Definition
they are much bigger. they are about 200 nm in diameter. this allows whole organelles and big molecules to go across the membrane
Term
how can loss of cadherin promote cancer growth?
Definition
it can allow the cancer cells to travel to other places and transition from benign to invasive
Term
how can gain of cadherin promote cancer growth?
Definition
it can promote invasion and metastasis
Term
Why does a plant need a cell membrane
Definition
to act as a selective permeability barrier
Term
what is ground substance?
Definition
fibers embedded in a viscous gel made up of glycoproteins, glycosaminoglycans, and proteoglycans, form a gooey substance, give the cell time to recognize and treat harmful substances
Term
what is the basement membrane or basal lamina?
Definition
provides anchoring matrix for cells
Term
What is a glycoprotein?
Definition
mostly protein with 1 or more short oligosaccharide chains made up of 6-8 sugar types
Term
what is a proteoglyan?
Definition
protein with one or more GAG covalently attached to it
Term
what is a GAG
Definition
glycosaminoglycan
repeating dimers of an amino sugar and a sugar or sugar acid
sulfating makes the GAG highly negatively charged - attracts water and cations
Term
hyaluronic acid
Definition
only GAG that isn't usually attached to a protein
Term
Cell-cell adhesion molecules (4)
Definition
1) CAMs (cell adhesion molecules)
2) cadherins
3) selectins
4) integrins
Term
Cadherens need -
Definition
calcium to function
Term
Selectin
Definition
cell surface glycoprotein the binds to terminal sugars on other cells
Term
What are zonula occludes regulated by?
Definition
claudin expression
Term
Desmosomes - special hair
Definition
intermediate filaments make hairpin turn in the attachment plaque on the cytoplasmic face
Term
what is the cutoff of MW that gap junctions allow ionic communication between cells?
Definition
about 1200 MW
Term
t/f not all collagen is alike
Definition
true can be about 25 different types of collagen
Term
Proteoglycan function (5)
Definition
1) control diffusion
2) barrier to bacteria
3) lubrication
4) modulate growth factor activity
5) packaging histamine in mast cells
Term
Where are laminas found
Definition
basal lamina
Term
Size of laminins
Definition
bigger than 850,000 MW
Term
integrins
Definition
membrane receptor that binds to ECM
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