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Flashcards in Extracellular Matrix & Connective Tissue Deck (68):
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.

proteoglycans

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 ___.

structural; adhesion, migration

3

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

core; glycosaminoglycans

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.

disaccharide; hexosamine, uronic

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

sieves

6

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

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

7

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

hyaluronic acid

8

Keratan sulfate I is attached via ____ residues

asparagine

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

sugar

10

____-sugars are the substrates for proteoglycan synthesis

UDP

11

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

glycosyltransferases

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?

PAPS
(3' phosphoadenosine 5')

13

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

extracellular matrix

14

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

aggregate

15

What is the function of hyaluronic acid?

cell migration, embryogenesis, morphogenesis, wound healing

16

What is the function of chondroitin sulfate?

formation of bone, cartilage, cornea

17

What is the function of keratan sulfate?

transparency of cornea

18

What is the function of dermatan sulfate?

transparency of cornea, binds LDL to plasma wall

19

What is the function of heparin?

anticoagulant, releases lipoprotein lipase from capillary walls

20

What is the function of heparan sulfate

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

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

glycoproteins

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.

serine; threonine; asparagine

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

N-acetyl-galactosamine

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.

Golgi

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

free; secondary

26

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

oligosaccharide

27

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

glycosyltransferase

28

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

protein-oligosaccharide

29

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

endocytosis

30

The carbohydrate moiety is degraded by the lysosomal ____

glycosidases

31

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

endoglycosidases; exoglycosidases

32

All collagen types have a ____ ____ structure

triple helical

33

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

left

34

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

right; hydrogen

35

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

glycine

36

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

proline; hydroxyproline

37

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

preprocollagen

38

In regard to collagen synthesis, extension peptides contain ___ residues

cysteine (disulfide bridges)

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

prolyl hydroxylase

40

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

Y

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

interruptions

42

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

IV

43

Where is Type I collagen found?

skin, bone, tendon, blood vessels, cornea

44

Where is type II collagen found?

cartilage, intervertebral disk, nitrous body

45

Where is type III collagen found?

blood vessels, fetal skin

46

Where is type IV collagen found?

basement membrane

47

Where is type V collagen found?

same as type I

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.

Ehlers-Danlos syndrom

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.

IV

50

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

VI

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.

VIIC

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.

alport syndrom

53

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

vitamin C

54

What are the major signs of scurvy?

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

55

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

elastin

56

Elastin is synthesized in a single ___ molecule.

tropoelastin

57

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

true

58

____ are the major cross-links of elastin

desmosines

59

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

williams

60

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

aortic stenosis

61

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

fibroblasts

62

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

marfan syndrom

63

Marfan syndrome is due to a mutation in the ___ gene

fibrillin

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

fibronectin

65

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

integrin

66

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

true

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

laminin

68

What are the three primary components of the basal lamina?

laminin, entactin, and type IV collagen