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Biochem Final > Oral Tissues > Flashcards

Oral Tissues Flashcards

1
Q

what is the most abundant protein in the body?

A

collagens

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2
Q

how many types of collagen is there?

A

28

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3
Q

what is the most common type of collagen?

A

Type I (makes up 80-90%)

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4
Q

what is the starting material for mature collagen?

A

pro-a collagen chains

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5
Q

what is the base unit structure for all collagen?

A

chains of tightly wound RIGHT turned triple helices

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6
Q

what can be mix and matched to make the different types of collagens?

A

different combinations of 3 pro-a collagen chains

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7
Q

what is a defining feature of collagen?

A

33? glycine
13% proline
9% hydroproline
in its repeating tripeptide form

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8
Q

what is special about glycine in the triple helix?

A

its a small R group and flexible so can form tightly packed, allows helix turns

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9
Q

what is special about proline/hydroproline in the triple helix?

A

ridged, provides strength

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10
Q

what bonds strengthen and stabilize collagen?

A

hydrogen and covalent bonds
(hydroxylation)

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11
Q

what is the difference between tropocollagen and procollagen?

A

pro still has carboxyl terminal extension peptides
tropo has these removed, it is just the triple pro-a helix

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12
Q

what occurs within the post translational modification of prolines and lysine’s

A

redox reactions that require Vit C as reducing agent

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13
Q

what are proline and lysine reduced to?

A

4-hydroxyproline residue or 5-hydroxylysine residue
succinate
CO2

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14
Q

what is the only irreversible aspect of scurvy?

A

bone growth in children

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15
Q

Collagen is a _______

A

glycoprotein

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16
Q

Most glycoproteins are ______ or _____ linked in collagen, this also includes hydroxylysine

A

N-linked (Asparagine) or O-linked (Serine or Threonine)
(he said not a test Q)

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17
Q

Covalent attachment of disacharides to hydroxylysine on collagen occurs in these two steps:

A

first galactose and then glucose

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18
Q

what does glycosylation not effect?

A

biochemical properties or
immunogenicity

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19
Q

crosslinks in collagen form both within _____ and _______

A

1 triple helix and between adjacent triple helices

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20
Q

The _____ route predominates in skin, cornea and sclera

A

allysine

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21
Q
  • The ______ route predominates in bone, cartilage,
    ligaments and tendons
A

hydroxyallysine

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22
Q

what is the first step of Biosynthesis of collagens

A

Pre-pro-α chains are synthesized in rough ER, where signal peptide is cleaved

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23
Q

what is the second step of Biosynthesis of collagens

A

Prolines and lysines in pro-α chains are hydroxylated

THIS IS VIT C DEPTENDANT STEP

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24
Q

what is the third step of Biosynthesis of collagens

A

Glycosylation of pro-α chains occurs in the smooth ER

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25
Q

what is the fourth step of Biosynthesis of collagens

A
  1. Triple helix-containing procollagen forms inside the Golgi
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26
Q

what is the fifth step of Biosynthesis of collagens

A
  1. Cleavage of extension peptides occurs outside the cell, as does assembly of tropocollagen units into collagen fibers
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27
Q

how are fibrillar collagens assembled?

A

10% extension area, 90% overlap,
this makes strong and lengthens

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28
Q

what is the arrangement of fibrillar collagens in tendons?

A

Parallel Bundles

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29
Q

what is the arrangement of fibrillar collagens in cartilage?

A

No regular arrangement; associated with glycosaminoglycans

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30
Q

what is the arrangement of fibrillar collagens in skin?

A

Planar sheets of microfibrils layered wat many angles

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31
Q

what is the arrangement of fibrillar collagens in cornea?

A

Planar sheets stacked crossways for strength

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32
Q

what does collagen IX do?

A

Connects collagens to cells and other matrix components

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33
Q

where is collagen X made

A

Produced by chondrocytes, required for normal bone growth

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34
Q

where is collagen IV found?

A

Unique to basement membranes

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35
Q

what collagen pays a roe in muscular dystrophy?

A

Collagen VI

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36
Q

what does collagen VII do?

A

epiderma BM to dermal CT

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37
Q

where is transmembrane collagens found?

A

connective tissue expressing cells

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38
Q

what do multipexins do?

A

proteoglycans expressed in endothelial and epithelial cell

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39
Q

what are some symptoms of Ehlers Danlos syndrome?

A

skin hyperelasticisty
fragile tissue
joint hypermobility

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40
Q

what causes osteogenesis imperfecta?

A

altered collagen type I
(type 1 causes had normal collagen, type II causes fully disrupted collagen)

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41
Q

what is a similarity shared by elastin and collagen?

A

high in glycine and proline
Covalent bonds provide
strength

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42
Q

what are some differences in Elastin than collagen

A
  • Unlike collagen, no
    repeating patterns
  • Alternating coiled-coil
    domains and hydrophobic
    domains create elasticity
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43
Q

in elastin fibrils _______ is identical to covalent links found in collagen

A

Lysinorleucine

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44
Q

_______ results from
identical chemical reactions,
but is unique to elastin

A

Desmosine

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45
Q

what is Fibrillin

A

–provides a scaffold for elastin deposition
–forms more rigid microfibrils in tissues where
elastin is not present

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46
Q

what do fibrillin/Elastin microfibrils do?

A

facilitate flexibility of skin,
ligaments, and blood
vessels.

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47
Q

Fibrillin microfibrils provide:

A

limited elasticity; the majority comes from elastin INSTEAD
provide support for bones, and
tissues that support nerves, muscles and lenses of the eye

48
Q

what is marfan syndrome?

A

defect in Fibrillin
longer than normal limbs, fingers, cardiac risk with too stretchy arteries

49
Q

what makes bone and teeth so hard?

A

Collagen Microfibrils Hydroxyapatite Crystals

50
Q

what does collagen do for bones

A

shape and strength

51
Q

what does hydroxyapatite do for bones?

A

bone hardness

52
Q

what does acid do to bones?

A

decalcifies them which is why they get soft (or get cavities)

53
Q

collagen has sites for ____ of hydroxyapatite crystals

A

nucleation

54
Q

________ Removes Inhibitor of Hydroxyapatite formation

A

Pyrophosphatase

55
Q

Pyrophosphatase limits formation of what?

A

crystal formation

56
Q

what is the structural organization of bone?

A

amino acids, tropocollagen, mineralized collagen fibrils, fibril arrays, fiver patterns, osteons/haversian canals, bone

57
Q

acidity shifts equibrium of bone toward what?

A

toward dissociation of hypocyapitite crystals

58
Q

_____ and _____ are critical for osteoclast differentiation, but process also required Ca2+-dependent NFAT activity

A

RANKL and m-CSF

59
Q

Osteoblasts differentiate
from stroma and regulate
________ differentiation

A

osteoclast differentiation

60
Q

what are the physiological roIes of osteocIasts?

A
  • Osteoclasts are essential for sustaining serum Ca2+ levels
  • Works in concert with osteoblasts for maintenance of healthy bone
61
Q

pathological roles of osteoclasts

A

Mediates bone erosion in osteoporosis, arthritis, multiple myeloma,
tuberculosis, anorexia.

62
Q

Why does bone erosion happen in so many different
inflammatory conditions?

A

because rank aIso triggers NFkB causing pro inflammatory activation

63
Q

Crosstalk between _______ and _______ cause bone erosion during arthritis

A

RANK and inflammatory cytokines

64
Q

bone erosion during arthritis happens from

A

introduction of foreign collagen

65
Q

why does bone loss occur with menopause?

A

lack of regulation of interleukin 6 by estrogen makes

66
Q

how does anorexia effect bones?

A

causes too many clasts resuting in bone loss

67
Q

how does menopause effect teeth?

A

causes loss of surrounding bone structure resulting in loss of teeth

68
Q

how are osteoclasts and blasts meditate bone remodeling?

A

mechanical force stimulates them to remodel (this is why astronauts without gravity get bone loss)

69
Q

what is the technique used for bone remodeling in orthodontics?

A

compression and tension forces in the root trigger the movement of the tooth

70
Q

what is the composition of enamel?

A

hypoxyapatite crystal: 90% Collagen: 0%

71
Q

what is the composition of dentin?

A

hypoxyapatite crystal: 70% Collagen: 18%

72
Q

what is the composition of cementum?

A

hypoxyapatite crystal: 65% Collagen: 19%

73
Q

what is the composition of bone?

A

hypoxyapatite crystal: 65% Collagen: 19%

74
Q

enamel has more what wereas bone has more

A

enamel: Ca
bone carbonate

75
Q

what is dental calculus made from?

A

calcium phosphate gets altered by bacteria

76
Q

what is the most abundant mineral in the human body?

A

calcium (and it is very tightly regulated)

77
Q

about how much Ca do we need each day?

A

1 g

78
Q

what effect does Ca have on cells?

A

potent signaling molecule, activates them

79
Q

what is the difference between a resting platelet and a Ca activated one?

A

regular look like disc, activated like pointy blob

80
Q

what are the roles of Ca in activating cells

A
  • Contraction of skeletal, cardiac and smooth muscle
  • Neurotransmitter release
  • T cell activation
    bone structure
81
Q

how does Ca impact thrombin?

A

esentay retracts blood clot

review the chart on side 439, draw it out

82
Q

how is Ca homeostasis maintained?

A

want to keep it at around 1g a day, take in much more through diet but only absorb to keep at 1g
(900mg to feces, 100mg to urine, excess stored in bones)

83
Q

what promotes osteoclasts?

A

PTH, Vit D
INHIBITED by Calcitonin

84
Q

what is necessary for ca absorption?

A

vit D and PTH

85
Q

PTH promotes

A

Ca resorption and phosphate excretion

86
Q

what triggers PTH release?

A

low blood ca

87
Q

what inhibits pth?

A

high blood ca

88
Q

what other thing stimulates PTH release other than Ca?

A

cAMP

89
Q

Extracellular calcium
sensing receptor (CaR)
is a ______

A

GPCR

90
Q

CaR activates Gai which inhibits ______

A

adenylate cyclase (AC)

91
Q

CaR activates Gaq which stimulates _____

A

PLC

92
Q

Ca2+ binding to Ca receptor has this effect:
* Gai _____
* cAMP _____
* PTH _____

A

activated
decreased
decreased

93
Q

Ca2+ binding to Ca Receptor has this effect:
* Gaq ______
* cytosolic Ca2+ ______
* PTH ______-

A

activated
increases
decreases

94
Q

how does PTH act on bone and kidney?

A

increases Ca uptake by kidney and increases osteoclasts/ activates vit D to get Ca from bones to increase blood Ca

95
Q

How PTH acts on the intestine:

A

PTH increases VitD, increases Ca absorption from food increases blood Ca
(no PTH receptor in intestine do does this through raising vit D)

96
Q

how do osteoclasts work?

A

secrete acid and proteases

97
Q

how do osteoblasts work?

A

Type 1 collagen, alkaline phosphatase, Ca2+ rich vesicles

98
Q

what happens with cronic ow Ca?

A

increased PTH mRNA

99
Q

Osteoclasts express receptors
for ______ and _______

A

M-CSF and RANKL

100
Q

Osteoblasts secrete the
ligands _____ and _____

A

M-CSF and RANKL

101
Q

Osteoblasts secrete _____
which neutralizes RANKL

A

OPG

102
Q

Effects of PTH on Bone:

A
  1. PTH stimulates osteoblasts to release M-CSF and RANKL
  2. M-CSF and RANKL stimulate
    -Differentiation of osteoclasts
    -Secrete acid and endopeptidases
  3. Growth factors released from bone activate osteoblasts
  4. Osteoblasts secrete
    -Collagen, Ca2+ vesicles
    -Alkaline phosphatase
    (cleaves PPi)
103
Q

M-CSF and RANKL stimulate:

A

-Differentiation of osteoclasts
-Secrete acid and endopeptidases

104
Q

how do Osteoclasts Erode Bone Matrix at the Ruffled Border

A
  1. Osteoclasts attach to bone
    surface through integrins
    * Integrins keep H+ high by
    “sealing” ruffled border to bone
  2. Carbonic anhydrase
    II generates H+
  3. H+ pumped out at ruffled border
    * H+ “dissolves” hydroxyapatite.
  4. Ca2+ and Pi are
    released by transcytosis.
105
Q

how does hyperparathyroidism or high PTH effect body?

A

increases risk of Kidney Stones
Bone fragility, Cardiac hypertrophy
HIGH URINE PHOS

106
Q

what occurs with hypothyroidism?

A

Multiple neurological effects
Heart failure, muscle cramps
Can be caused by injury,
hypomagnesemia, hypokalemia
and alkalosis
ow urine phos, high urine Ca

107
Q

what does calcitonin do?

A

counter balances PTH, inhibits bone resorption, stim Ca excretion

108
Q

where is calcitonin made?

A

thyroid gland
parafollicular cells

109
Q

what is calcitons actions for osteoclasts?

A

-decreases activity of ruffed boarder
-dedifferentiation of osteoclasts

110
Q

what protective feature does calcitonin provide?

A

protects against excessive bone resorption

111
Q

what does vitamin D do?

A

needed for Ca absorption, w/o it low Ca

112
Q

what happens with low Ca?

A

Vit D activated, PTH, 1,25 VIT D triggers Ca absorption from gut and bone while inhibiting excretion

113
Q

what happens with high Ca?

A

PTH inhibited, non active vit D calcitonin inhibits clasts, bones take Ca and kidneys excrete

114
Q

what happens with low vit D?

A

some resorpt from PTH
Rickets
* Low serum Ca2+
* Dental deformities
* Impaired growth
* Increased bone fractures
* Muscle cramps
* Short stature
* Skeletal deformities

115
Q

what happens with excess vit D?

A

rare but possibe, vit D becomes inactive, mre Ca absorbed, but more osteocasts so bones softened

Biochem Final (6 decks)

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