Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MMB > [008] Connective Tissue Fibrous Proteins: Shape and Function (α-Keratin, Elastin, Collagen) > Flashcards

[008] Connective Tissue Fibrous Proteins: Shape and Function (α-Keratin, Elastin, Collagen) Flashcards

1
Q

The CT’s ECM is made of ?

A

1)Water
2)minerals
3)proteoglycans
4) fibrous proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Main properties of fibrous proteins?

A

Extended protein structure.

Insoluble in water.

Secondary structure is simple based on one type.

Quaternary structure is it together by covalent Bridges.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Secondary structureOf alpha Keratin ?

A

Alpha helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

SuperSecondary Structure of Alpha Keratin ?

A

1)TWO parallel α -helices supercoil around each other to form a dimer
2) Each dimer associates antiparallel with another dimer in a staggered arrangement to form the protofibril.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The following picture shows the structure of Alpha Keratin , mention the hidden.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

…. Is a rubber like protein

A

Elastin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

… & … cells synthesize elastin

A

FibroblastsAnd chondrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where can elastin be found ?

A

elastic ligaments,
lung walls
blood vessel walls (large arteries, e.g. the aorta)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Diseases implicated with Elastin synthesis errors ?

A

Emphysema and CVDs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

…. Is the building unit of Elastin.

A

tropoelastin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

… secretes tropoelastin ?

A

Cells of ECM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

AA. Composition of elastin ?

A

1) Rich in lysine
2) and Allysine
3) They form large hydrophobic peptides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

… is an aldehyde form of lysine

A

Allysine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

…. (Protein) is rich in allysine.

A

Elastine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

… (enzyme) oxidatevly-deaminates lysine to Allysine.

A

lysine oxidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Function of large hydrophobic peptides present in Elastine

A

Their sidechains do not interact with each other by hydrogen bonds, and their role appears to allow the elastin network to deform.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How Tropoelastin forms Elastin ?

A

crosslinking of tropoelastin via lysine residues gives elastin extensive interconnection leading to a rubbery consistency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

This figure shows a type of crosslinking that takes place in formation of Elastin , mention the name of this link.

A

desmosine link (4 Lysine residues)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

This figure shows a type of crosslinking that takes place in formation of Elastin , mention the name of this link.

A

-lysinonorleucine link (2 Lysine residues)
linking 2 tropoelastin molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Mention the exact structure of the Desmosine cross-links in Elastin.

A

Formed of three allysine (modified lysine) plus one lysine residue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

…. Is the most abundant protein in the body.

A

Collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Mention the formation of type one Collagen

A

formed of 2 α1 chains and 1 α2 chain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

… &…(cells) makes collagen

A

fibroblasts and chondrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

… is the building unit of Collagen.

A

Tropocollagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Tropocollagen is formed of ?

A

three coiled peptides [left-hand α-chains] , tightly twisted to form a right handed superhelix.

26
Q

AA. Composition of tropocollagen ?

A

α-chain contains the repeating triplet sequence Gly-X-Y :
-The X position is ussually occupied by proline , sometimes lysine
-The y position is ussually occupied by hydroxyproline , sometimes hydroxylysine

27
Q

….(fibrous protein) is considered a a glycoprotein

A

Collagen

28
Q

…&…(sugar) molecules are attached to hydroxylysine residues in Collagen.

A

Glucose and galactose

29
Q

…(AA. In collagen) is responsible for collagen’s glycosilation.

A

hydroxylysine

30
Q

Why Collagen has a strong structure ?

A

1-Each turn contains 3 amino acid residues (makes a tight helix), normal proteins contain 3.3 a.a. / turn.

2- The presence of glycine with its short side chain makes the polypeptide chains very close to each other.

4-The high content of hydroxyproline forms hydrogen bonds between chains

5-The formation of covalent cross linkages between adjacent polypeptide chains is responsible for tensile properties of collagen.

31
Q

most common types of collagen ?

A

type I and type II.

32
Q

Type I Collagen consists of ?

A

(2 α1,, 1α2),

33
Q

Type II Collagen consists of ?

A

(3α1)

34
Q

Four stages of collagen assembly ?

A

(1) Synthesized as procollagen which is secreted from the cell
(2) Cleaved to tropocollagen by procollagen peptidase
(3) Assembly of tropocollagen leads to formation of the collagen fiber
4) Chemical crosslinking of tropocollagen strengthens the fiber

35
Q

Mention steps of procollagen formation

A

• The 3 separate pro-α chains are synthesized inside the cell.

• Selected Pro and Lys residues are hydroxylated to Hyp and Hyl

• Selected hydroxylysine residues are glycosylated

• Three pro-α chains assemble at the C-terminus end starting with disulphide bridge formation between the 3 chains.

• The 3 chains then “zip” up to form procollagen.

36
Q

• Three pro-α chains assemble at the …terminal end through …. (Bond) formation between the 3 chains.

A

C-terminal— disulphide bridge formation

37
Q

The figure shows an intermidiate structure in collagen formation ?

A

Procollagen

38
Q

…. Is a medical problem related to the formation of Procollagen

A

osteogenesis imperfecta

39
Q

Second stage of collagen formation ?

A

Cleavage of procollagen to tropocollagen

40
Q

….(enzyme) cleaves procollagen to tropocollagen.

A

procollagen peptidase

41
Q

Mention the secondary structure of tropocollagen

A

triple helix

42
Q

…. Is a medical problem related to tropocollagen formation

A

Ehlers-Danlos syndrome

43
Q

Third stage of collagen formation ?

A

Assembly of tropocollagen

44
Q

Explain the assembly of tropocollagen

A

• The formation of a one-quarter staggered array of tropocollagen molecules

• There are (40 nm) gaps between the tropocollagen molecules which is where calcium phosphate is deposited in bone formation

• This assembly forms spontaneously by means of noncovalent hydrogen bond interactions involving the OH group of hydroxyproline

45
Q

The following figure illustrates a step in collagen formation , explain it

A

• The formation of a one-quarter staggered array of tropocollagen molecules (i.e. each of which is displaced lengthwise by a quarter of its length)

• There are (40 nm) gaps between the tropocollagen molecules which is where calcium phosphate is deposited in bone formation

• This assembly forms spontaneously by means of noncovalent hydrogen bond interactions involving the OH group of hydroxyproline

46
Q

… is a medical condition related to the 3rd step of collagen formation

A

Scurvy

47
Q

Fourth stage of collagen formation is ?

A

Crosslinking of collagen fiber

48
Q

Explain the Fourth stage of collagen formation

A

-Crosslinking of collagen fiber
- Collagen fibre is stabilized by covalent crosslinks between lysine residues.

49
Q

… is a medical problem related to the Crosslinking of collagen fiber (4th stage)

A

lathyrism

50
Q

…. Is alo known as brittle bone syndrome.

A

Osteogenesis imperfecta

51
Q

Pathogenesis of Osteogenesis imperfecta ?

A

-Results from a mutant collagen gene: a buried Glycine residue is mutated to Cystein in procollagen
• The triple helix is partially unfolded at the N-terminal end

• The tropocollagen subunits are not tightly packed, and collagen fiber formation is weaker

• Patients suffer from skeletal deformities

52
Q

Manifestations of Osteogenesis Imperfecta ?

A

• deformed bones which can easily be fractured
• slight spinal curvature
• loose joints
• long tapering extremities
• poor muscle tone
• sometimes with hearing loss or blue sclerae

53
Q

Pathogensis of Ehlers-Danlos syndrome ?

A

• Results from reduced levels of procollagen peptidase, so procollagen is not fully converted into tropocollagen
• A high level of procollagen is found in the skin and tendons of patients
• The 40 nm gaps between tropocollagen molecules become blocked by uncleaved peptides which prevent lysine oxidase from acting on tropocollagen to create the crosslinks (no crosslinks)

54
Q

Ehlers-Danlos syndrome patients suffer from ?

A

stretchable skin
-hypermobile joints
-short stature

55
Q

…. Is also called the famous disease of medieval Europe

A

Scurvy

56
Q

Pathogenesis of Scurvy ?

A

• is related to assembly of tropocollagen
• Hydroxyproline is important for the correct assembly of collagen fibers.
• Hydroxyproline is only formed from Proline residues after procollagen has been formed.
• This reaction of Proline with proline hydroxylase requires ascorbate (Vitamin C) as a cofactor

57
Q

• Complications of scurvy ?

A

• poor collagen fibril formation
• skin lesions develop and wounds do not heal
• blood vessel walls are fragile
• bleeding under the skin and in gums
• falling of teeth

58
Q

…. Is another form of Ehlers Danlos syndrome.

A

Lathyrism

59
Q

Pathogenesis of Lathyrism ?

A

A Diet induced disease Caused by inhibition of lysine oxidase by:
• ingestion of sweet pea seeds(contain β-aminopropionitrile)
• may be due to copper deficiency in diet This affects the cross-linking of collagen

60
Q

Lathyrism is Characterized by:

A

• Deformation of spine
• Dislocation of joints
• Demineralization of bones
• Joint hemorrhage
• Aortic aneurism

MMB (72 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions