ECM/Cell Junctions

Question 1

the ECM is a complex network of ____ in the extracellular space

Answer 1

macromolecules

Question 2

the ECM is secreted by:

Answer 2

the cells in which inhabit it

Question 3

the ECM is a substantial contributor to ____

Answer 3

tissue volume

Question 4

ECM gives ____ and ____ support to cells and tissues

Answer 4

structural; organizational

Question 5

the ECM regulates cellular processes like ___, ____, and ____

Answer 5

proliferation; differentiation; migration

Question 6

4 main families of molecules comprise the ECM

Answer 6

1. collagens
2. elastins
3. glycoproteins
4. proteogycans

Question 7

collagen molecules are a ____ composed of 3 ____ chains

Answer 7

triple helix; polypeptide

Question 8

each polypeptide chain of collagen is itself ____

Answer 8

helical

Question 9

collagens have a characteristic repeating sequence of ____

Answer 9

Gly-X-Y

Question 10

intra and inter chain helices of collagen are stabilized by ____

Answer 10

H bonding

Question 11

collagen is ___ of total body protein, ___ of it is ____

Answer 11

30% ; 90% ; type I collagen

Question 12

defective type I collagen causes _____

Answer 12

osteogenesis/dentogenesis imperfecta

Question 13

genetic defects cause the ____ in the collagen chain to be replaced by other amino acids; collagen chains cannot fold correctly into ____; the resulting ____ are defective

Answer 13

glycine; triple helices; collagen fibrils

Question 14

type ___ collagen forms a matrix

Answer 14

IV

Question 15

type IV collagen associates with ____ collagens, forming a mesh-like structure

Answer 15

fibrillar

Question 16

type IV collagen is a major structural component of ____, _____, and _____

Answer 16

basement membranes; vascular walls; the glomerulus

Question 17

anomalies in type IV collagen in the glomerulus cause disease:

Answer 17

Goodpasture’s syndrome- autoimmune disease

Alport syndrome- defective type IV collagen chains

Question 18

elastins provide ____ and ____ and are the dominant ECM protein in ____

Answer 18

flexibility; resilience; blood vessels

Question 19

elastins are abundant in ____, ____, and ____

Answer 19

skin; lungs; intestines

Question 20

elastins are stabilized by ____ crosslinks; crosslinks contains ____

Answer 20

two-way; desmosine

Question 21

types of glycoproteins:

Answer 21

fibronectin; laminin

Question 22

there are at least 20 types of fibronectin, with ___ and ____ forms

Answer 22

soluble; insoluble

Question 23

fibronectin is produced by ____ of a single precursor ____

Answer 23

alternative splicing; mRNA

Question 24

alternative splicing controlled by many factors and processes:

Answer 24

• tissue or cell of origin
• embryogenesis
• wound healing
• oncogenesis

Question 25

fibronectin facilitates communication between intracellular and extracellular compartments, important for:

Answer 25

cell adhesion, growth, migration, differentiation, embryogenesis, and wound healing

Question 26

loss of fibronectin from the surface of ____ may help initiate ____

Answer 26

tumor cells; metastasis

Question 27

fibronectin binds to ___ molecules on cells

Answer 27

integrin

Question 28

soluble fibronectin in saliva prevents ____, _____, and other oral pathogens from binding to the oral cavity

Answer 28

streptococcus mutans; porphyromonas gingivalis

Question 29

laminin is vital for ____ and ____; laminin is an integral part of the ____

Answer 29

tissue maintenance; survival; ECM scaffolding

Question 30

defective laminins can causes diseases:

Answer 30

- muscular dystrophies - lethal skin blistering disease, epidermolysis bullosa - defects of kidney filter

Question 31

laminin found primarily in ____, gives ____ support to the ECM

Answer 31

basal lamina; structural

Question 32

laminin is the major component of basement membranes in ____ and ____ tissues

Answer 32

epithelial; muscle

Question 33

laminin binds to cells, often through the ____ family of proteins

Answer 33

integrin

Question 34

epithelium attaches to implants by a longer ____ as compared with a natural tooth

Answer 34

junctional peri-implant epithelium

Question 35

proteoglycans combine to form ____

Answer 35

aggrecan

Question 36

in the cartilage matrix, individual proteoglycans are linked to a nonsulfated GAG, called ____, to form a giant complex with a molecular mass of about 3 million

Answer 36

hyaluronic acid

Question 37

functions of proteoglycans

Answer 37

- structural support - gel formation due to hydration - tissue-specific functions

Question 38

tissue specific functions of proteoglycans

Answer 38

- bind growth factors - regulate the activity of specific proteins (regulate enzyme activity) - act as co-receptors

Question 39

proteoglycans have many ____ charges, which attract ____ and ____

Answer 39

negative; cations; water

Question 40

the negative charges of proteoglycans result in ____ of the ECM, which provides ____ and ____

Answer 40

hydration; rigidity; durability

Question 41

proteoglycans are < 10% of ECM protein, but because of their ____, ____ fill most of the extracellular space

Answer 41

hydrophilicity; GAG chains