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ODDR-Microbiology & BioChem > Biochem of the PDL 1 > Flashcards

Biochem of the PDL 1 Flashcards

1
Q

what’re the cells present in the PDL

A

fibroblasts
cementoblasts
osteoblasts

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2
Q

what’re the fibres present in the extracellular matrix called

A

major fibres = collagen
minor fibres = oxytalan elaunin, (elastin in mature fibres)

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3
Q

what type of fibres are elastin fibres found in

A

mature

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4
Q

what are oxytalan fibres also known as

A

immature elastin fibres

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5
Q

what type of collagen fibres are present in the PDL

A

mostly I but also III

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6
Q

what’s the structure of collagen fibres

A
  • 3x polypeptide chains
  • triple helix
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7
Q

What’s the primary structure (a.a) of a-chains in type 1 collagen

A

GLY-X-Y

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8
Q

In the primary structure of a-chains of type 1 collagen what does the X stand for
+ what happens to the characteristics of it

A

PRO or HYP
- more stability & forming H-bonds

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9
Q

what disease can occur if collagen fibres aren’t hydroxylated

A

scurvy (absence of vit.C)

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10
Q

what’s tropocollagen

A

an individual collagen fibre (not connected to another)
-no terminal propeptides

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11
Q

what’re the 2 terminals on procollagen molecules

A

-C -N

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12
Q

why can’t procollagen form fibres?

A

due to terminal propeptides at each end

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13
Q

What post-secretory enzyme makes procollagen -> tropocollagen
+how does it do this

A

procollagen peptidases
- cleave off N- and C- propeptides
- this allows it to form fibres

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14
Q

how is tropocollagen arranged when in fibres (what’s the name of the structure)

A

1/3 stagger array

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15
Q

what’re the links between tropocollagen molecules called

A

reducible intermolecular cross links

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16
Q

what does Lysyl oxide do

A

converts R groups to aldehyde form:
LYS -> allysine (aldehyde form)
HYL -> hydroxyallysine (aldehyde form)

+ Forms reducible intermolecular cross-links

17
Q

what types of bonds are reducible intermolecular cross links

A

covalent

18
Q

reducible intermolecular cross links can be formed between all combinations of ___ and ___ + their _____
+ where they called

A

LYS & HYL & their aldehyde forms
allysine + LYS = LNL
allysine/LYS + HYL = HLN
HYL + HYL = DHLN

19
Q

what’s the ratio of DHLN:HLN in the PDL

A

1:3

20
Q

are there non-reducible cross links in the PDL & why

A

no
due to fast cell turnover

21
Q

what’re the overall steps of Collagen I biosynthesis
(HINTS
1. s______ of _______ in the ____
2. h______ of ______ & _____ with use of ______
3. g________ of ____ & ______
4. _____ bonds forming of the _______
5. Forming a _____
6. Final processing step in the ______ to add more ____
7. secretion
8. Cleave ____ with use of ________
9. ________ formed
10. Formation called the _________
11.intermolecular cross link formed by _____

A
  1. synthesis of a-chains in RER
  2. hydroxylation of PRO & LYS (w. vit.C)
  3. glycostlation of HYL & allysine
  4. S-S bonds of pro-a-chains
  5. procollagen triple helix formed
  6. more sugars added in Golgi
  7. secretion
  8. cleave terminals propeptides (procollagen peptidases)
  9. tropocollagen formed
  10. quater stagger array
  11. cross link formation (lysyl oxidase)
22
Q

is procollagen intracellular or extracellular

A

intracellular

23
Q

is tropocollagen intracellular or extracellular

A

extracellular

24
Q

what’re the enzymes called that help degrade collagen

A

collagenases

25
Q

What cells form collagen in the PDL

A

fibroblasts

26
Q

what 2 ions do collagenases need to work

A

Ca2+ & Zn2+

27
Q

what inhibits collagen degradation

A

TIMP

28
Q

what’re the biochemical changes in the PDL in case of disease in terms of collagen & gelatinases

A

collagen content decreases
gelatinise activity increases

29
Q

what do gelatinises do

A

further degradations of collagen in the PDL

30
Q

What enzyme is responsible for the post-translational modification of PRO->HYP
+ what’s the co-factor
+ what’s the reducing agent

A

Prolyl hydroxylase
+ Fe2+
+ Vit.C

31
Q

How is procollagen assembled(4)
1. _____ assemble at _ terminal
2. _____ bonds formed which add ______
3. _______ formation
4. _______ added in the ___ & _____

A

A-chains assemble at C terminal
S-S = stabilised
Spontaneous helix formation
Sugars added in RER & Golgi

32
Q

How is tropocollagen formed

A

1.Procollagen
2.procollagen peptidases
3. Cleaves N- & C- propeptides
4.=tropocollagen

33
Q

How are fibrils stabilised
+ what’re the cross links between

A

Covalent cross links
LYS HYL

34
Q

How do non-reducible cross links form

A

Spontaneously with age

35
Q

The PDL has non-reducible cross-links (true or false) + why

A

False
+ rapid turnover rate in collagen

36
Q

Are collagenases endopeptidases or exopeptideases
+ why

A

Endopeptidases
+ cleaves collagen fibres in the middle of the chains, not at either end

37
Q

When collagen degradation takes place, what fragment lengths are they cleaved into?

A

1/4 +3/4

ODDR-Microbiology & BioChem (3 decks)

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