Extracellular Matrix & Connective Tissue

Question 1

The following describes the structure of what biomolecule found in the extracellular matrix:
found in synovial fluid of joints, arterial walls, bone and cartilage, and the ocular vitreous humor.

Answer 1

proteoglycans

Question 2

Proteoglycans interact with proteins in the matrix such as collagen and elastin, fibronectin, and laminin. Collagen and elastin play ___ roles. Fibronectin is involved in cell ___ and ___.

Answer 2

structural; adhesion, migration

Question 3

Proteoglycans consist of a ___ protein covalently attach to many long, linear chains of _____.

Answer 3

core; glycosaminoglycans

Question 4

Glycosaminoglycans are made of repeating ____ units. These repeating units usually contain a ____ and an ___ acid. These sugars are frequently sulfated. Therefore they repel each other (due to negative charge) and act as a lubricant.

Answer 4

disaccharide; hexosamine, uronic

Question 5

Proteoglycans occupy a very large space and act as “molecular ____”. These properties give some flexibility to substances such as cartilage, compression and re-expansion

Answer 5

sieves

Question 6

There are at least seven types of glycosaminoglycans, which differ in the monosaccharides present in their repeating disaccharide units. Name all 7.

Answer 6

chondoritin sulfate
dermatan sulfate
heparan
heparan sulfate
hyaluronic acid
keratan sulfate I
keratan sulfate II

Question 7

All glycosaminoglycans except ___ ___ are attached to proteins by covalent linkage to serine or threonine residues.

Answer 7

hyaluronic acid

Question 8

Keratan sulfate I is attached via ____ residues

Answer 8

asparagine

Question 9

Once the protein enters the ER, synthesis of the proteoglycans starts with the attachment of a ___ to serine or threonine residues of the protein

Answer 9

sugar

Question 10

____-sugars are the substrates for proteoglycan synthesis

Answer 10

UDP

Question 11

Specific UDP-sugar ________ are responsible for sequential transfer of monosaccharides from a nucleotide-linked sugar to an appropriate acceptor

Answer 11

glycosyltransferases

Question 12

Sulfate groups are added through N- and O-sulfation, and they occur after the addition of sugars. What provides the sulfate groups for this reaction?

Answer 12

PAPS

3’ phosphoadenosine 5’

Question 13

Once the synthesis of the proteoglycan is complete, it is secreted and forms the ___ ____

Answer 13

extracellular matrix

Question 14

Proteoglycan ___ is formed by nonequivalent interaction between core protein and hyaluronic acid

Answer 14

aggregate

Question 15

What is the function of hyaluronic acid?

Answer 15

cell migration, embryogenesis, morphogenesis, wound healing

Question 16

What is the function of chondroitin sulfate?

Answer 16

formation of bone, cartilage, cornea

Question 17

What is the function of keratan sulfate?

Answer 17

transparency of cornea

Question 18

What is the function of dermatan sulfate?

Answer 18

transparency of cornea, binds LDL to plasma wall

Question 19

What is the function of heparin?

Answer 19

anticoagulant, releases lipoprotein lipase from capillary walls

Question 20

What is the function of heparan sulfate

Answer 20

component of skin fibroblast and aortic wall, commonly found on cell surfaces

Question 21

The following describes the structure of what biomolecule:
usually contain shorter carbohydrate chain than proteoglycans, The carbohydrate moiety is often branched and is not made of repeating disaccharides. Most circulating proteins in the blood are this biomolecule

Answer 21

glycoproteins

Question 22

In synthesis of glycoproteins, carbohydrate monomers are added to the protein in the lumen of ER and the golgi complex. In most cases, the initial sugar is added either through O-linkage to ___ or ___ residues, or N-linkage to an ___ residue.

Answer 22

serine; threonine; asparagine

Question 23

In regards to O-linked glycosides, glycosylation of the protein begins with the attachment of an __________ onto a specific serial or threonyl side chain of the protein

Answer 23

N-acetyl-galactosamine

Question 24

In regards to O-linked glycosides, glycoproteins that are destined to plasma membrane will be integrated to the Golgi membrane with glycosyl moiety facing the ___ lumen.

Answer 24

Golgi

Question 25

In regards to O-linked glycosides, glycoproteins that are destined to be secreted from the cell remain ___ in the lumen. ___ vesicles bud off the Golgi and fuse with the cell membrane releasing the glycoproteins to the extracellular space

Answer 25

free; secondary

Question 26

In regards to N-linked glycosides, the protein itself does not become glycosylated with individual sugars; instead a lipid-linked _______ is first constructed.

Answer 26

oligosaccharide

Question 27

In regards to N-linked glycosides, after the oligosaccharide is constructed, the sugars are then added by the membrane-bound _______

Answer 27

glycosyltransferase

Question 28

Oligosaccharides are transferred from the dolichol to asparagine residues of the protein by a ____-_____ transferase enzyme present in the ER

Answer 28

protein-oligosaccharide

Question 29

Lysosomal enzymes degrade proteoglycans and glycoproteins bought into the cell by the process of ____

Answer 29

endocytosis

Question 30

The carbohydrate moiety is degraded by the lysosomal ____

Answer 30

glycosidases

Question 31

______ cleave carbohydrate chains to shorter oligosaccharides _____, specific for each type of linkage, remove the sugar residue from the nonreducing end

Answer 31

endoglycosidases; exoglycosidases

Question 32

All collagen types have a ____ ____ structure

Answer 32

triple helical

Question 33

Each polypeptide subunit or alpha chain of collagen is twisted into a ___-handed helix of three residues per turn

Answer 33

left

Question 34

Three alpha chains are then wound into a ___-handed superhelix. ____ bonding stabilizes this triple helix.

Answer 34

right; hydrogen

Question 35

______ residues occur at every third position of the triple helical portion of the alpha chain

Answer 35

glycine

Question 36

____ and ____ residues as X and Y in Gly-X-Y increase rigidity of the collagen

Answer 36

proline; hydroxyproline

Question 37

Collagen is synthesized as a ____, which contains a signal sequence and polypeptide extensions

Answer 37

preprocollagen

Question 38

In regard to collagen synthesis, extension peptides contain ___ residues

Answer 38

cysteine (disulfide bridges)

Question 39

Hydroxyproline is formed post-transcriptionally by hydroxylation of the proline residues by a ___ ___ enzyme. The enzyme requires ascorbic acid and alpha ketoglutarate as cofactors

Answer 39

prolyl hydroxylase

Question 40

Lysine and hydroxylysine can participate in the __ position in Gly-X-Y

Answer 40

Y

Question 41

Several collagen types do not form fibrils in tissues. They are characterized as "____" of the triple helix with stretches of protein lacking Gly-X-Y repeat structures

Answer 41

interruptions

Question 42

Collagen ___ is the best known example of collagens with discontinuous triple helices

Answer 42

IV

Question 43

Where is Type I collagen found?

Answer 43

skin, bone, tendon, blood vessels, cornea

Question 44

Where is type II collagen found?

Answer 44

cartilage, intervertebral disk, nitrous body

Question 45

Where is type III collagen found?

Answer 45

blood vessels, fetal skin

Question 46

Where is type IV collagen found?

Answer 46

basement membrane

Question 47

Where is type V collagen found?

Answer 47

same as type I

Question 48

This syndrome comprises a group of inherited disorders whose principal clinical features are hyper extensibility of the skin, abnormal tissue fragility, and increased joint mobility.

Answer 48

Ehlers-Danlos syndrom

Question 49

Type ___ Ehlers-Danlos syndrome is the most serious because of its tendency for spontaneous rupture of arteries of the bowel, reflecting abnormalities in collagen III.

Answer 49

IV

Question 50

Type ____ Ehlers-Danlos syndrome is due to lysl hyroxylase deficiency. Patients exhibit marked joint hyper mobility and tendency to ocular rupture

Answer 50

VI

Question 51

Type ___ Ehlers-Danlos syndrome is due to procollagen N-proteinase deficiency, causing formation of abnormal thin, irregular collagen fibrils, manifested by marked joint hyper mobility.

Answer 51

VIIC

Question 52

This syndrome is referred to a group of genetic abnormalities affecting the structure of type IV collagen fibers. Patients are represented with hematuria and may eventually develop end-stage renal disease due to basal membrane abnormalities.

Answer 52

alport syndrom

Question 53

Scurvy affects the structure of collagen due to a deficiency in what vitamin?

Answer 53

vitamin C

Question 54

What are the major signs of scurvy?

Answer 54

bleeding gums, subcutaneous hemorrhages, and poor wound healing (due to deficiency of prolyl and lysyl hydroxylase activity)

Question 55

___ is a connective tissue that is responsible for properties of extensibility and elastic recoil in tissue

Answer 55

elastin

Question 56

Elastin is synthesized in a single ___ molecule.

Answer 56

tropoelastin

Question 57

True or false? | elastin does not have extension peptides, Gly-X-Y arrangement, triple helical structure, or carbohydrate moiety

Answer 57

true

Question 58

____ are the major cross-links of elastin

Answer 58

desmosines

Question 59

Deletions in elastin gene have been found in 90% of subjects with ___ syndrome, a developmental disorder affecting connective tissue and the CNS

Answer 59

williams

Question 60

Mutations effecting the synthesis of elastin probably play a causative role in the supravalvular ___ ____ often found in this condition

Answer 60

aortic stenosis

Question 61

Fibrillin is a large glycoprotein found in many tissues. It is secreted into the extracellular matrix by ____

Answer 61

fibroblasts

Question 62

This is an autosomal dominant disease affecting connective tissue. Most patients exhibit long digits and hyperextensibility of the joints, and cardiovascular problems

Answer 62

marfan syndrom

Question 63

Marfan syndrome is due to a mutation in the ___ gene

Answer 63

fibrillin

Question 64

This is a soluble glycoprotein found in large amounts in the extracellular matrix. It is a dimer, joined by disulfide bonds near their terminal

Answer 64

fibronectin

Question 65

Fibronectin receptor belongs to a family of transmembrane ___ class of proteins

Answer 65

integrin

Question 66

Fibronectin contains Arg-Gly-Asp sequence that binds to integrin. True or false?

Answer 66

true

Question 67

This consists of a3 distinct elongated polypeptide chains linked to together to form an elongated cruciform shape. It has a binding site for type IV collagen, heparan, and integrin on the cell surface

Answer 67

laminin

Question 68

What are the three primary components of the basal lamina?

Answer 68

laminin, entactin, and type IV collagen