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Applied Biochemistry > Biochemistry Of Bone Formaton (Exam V) > Flashcards

Biochemistry Of Bone Formaton (Exam V) Flashcards

1
Q

The four phases of skeletal development:

A

1- Migration of preskeletal cells to sites of future skeletogenesis
2- Interaction of these cells with epithelial cells
3- Mesenchymal condensation
4- Cell differentiation to chondroblasts or osteoblasts

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2
Q

During skeletal development the pre-skeletal cells of mesenchymal origin travel to:

A

Sites of future skeletogenesis

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3
Q

During skeletal development the interactions of what types of cells leads to mesenchymal condensation:

A

Epithelial-mesenchymal interaction

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4
Q

Following the condensation phase of skeletal development, what can the cells differentiate into:

A

Chondroblasts or osteoblasts

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5
Q

Indirect method of forming bone

A

Endochondral bone formation

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6
Q

During endochondral bone formation, what does the mesenchyme first form:

A

Cartilage template

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7
Q

In endochondral bone formation the cartilage template forms in what shape:

A

Shape of the future bone

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8
Q

In endochondral bone formation the cartilage template will later be replaced by:

A

Mineralized bone tissue

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9
Q

What type of bone formation occurs in most bones of the skeleton especially bones that bear weight and have joints:

A

Endochondral bone formation

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10
Q

Type of bone formation that occurs during fracture repair:

A

Both endochondral & intramembranous

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11
Q

Long bones & bones with joints undergo _____ bone formation

A

Endochondral

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12
Q

Direct transformation of mesenchymal cells to osteoblasts:

A

Intramembranous bone formation

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13
Q

Type of bone formation that does not involve a cartilage intermediate

A

Intramembranous bone formation

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14
Q

Type of bone formation that is restricted to the cranial vault, some facial bones & parts of the mandible & clavicle:

A

Intramembranous

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15
Q

During endochondral bone formation-

The mesenchymal cells will intially condense to form a _____ that shows the _______ of the bone

A

Cartilage model
Future shape

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16
Q

During endochondral bone formation-

Following the condensation of mesenchymal cells to form the cartilage model, what occurs?

A

Differentiation & formation of mineralized collar

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17
Q

During endochondral bone formation-

Where does the differentiation & formation create the mineralized collar?

A

On outside of bone

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18
Q

During endochondral bone formation-

What is the first mineral to form?

A

Mineralized collar on outside of bone

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19
Q

During endochondral bone formation-

The formation of the mineralized collar on the outside of the bone causes:

A

The chondrocytes in the center to undergo hypertrophy

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20
Q

During endochondral bone formation-

What happens when the chondrocytes in the center of the bone undergo hypertrophy?

A
  • swell up
  • change gene expression pattern
  • start to calcify
  • secrete VEGF
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21
Q

During endochondral bone formation-

What produces & secretes VEGF?

A

Hypertrophic chondrocytes

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22
Q

During endochondral bone formation-

What does the secretion of VEGF by the hypertrophic chondrocytes accomplish?

A

Attracts blood vessels into the central area

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23
Q

During endochondral bone formation-

What comes in following the invasion of blood vessels into the central area via VEGF?

A

Osteogenic precursor cells
Osteoclasts

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24
Q

During endochondral bone formation-

The osteogenic precursor cells and osteoclasts brought in during the process of blood vessels invading the cartilage template are from what lineage?

A

Hemopoetic cell lineage

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25
Q

During endochondral bone formation-

Following the addition of the osteogenic precursor cells and osteoclasts (brought in by the blood vessels) what does the osteoclasts do?

A

The osteoclast will resorb the mineralized cartilage matrix in the middle

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26
Q

During endochondral bone formation-

Following the addition of the osteogenic precursor cells and osteoclasts (brought in by the blood vessels) what do the osteogenic precursor cells do?

A

The osteogenic precursor cells cause osteogenesis to occur

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27
Q

During endochondral bone formation, the chondrocytes secrete _____ which attracts ______ into the center which further recruits ______ & ______

A

VEGF
Blood vessels
Osteogenic precursors
Osteoclasts

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28
Q

During endochondral bone formation-

Following the osteoclasts resorbing the mineralized matrix in the center, and the osteogenic precursors initiating osteogenesis what is the next step to take place?

A

Formation of a marrow cavity

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29
Q

During endochondral bone formation-

What forms after the marrow cavity?

A

Trabecular bone

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30
Q

During endochondral bone formation-

Following the trabecular bone formation what will occur late on:

A

Secondary ossification center

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31
Q

Endochondral bone formation
1. Mesenchymal cells will initially condense to form ______ that takes on the shape of the bone
2. Differentiation & formation of the ______ on the outside of the bone
3. The collar mineralization cause the chondrocytes in the center to ________
4. The hypertrophic chondrocytes secrete _______
5. VEGF attracts ___ to enter the central canal
6. Blood vessels invade cartilage template and recruit _____ & _____
7. The osteoclasts will ____ the mineralized cartilage matrix in the middle, while the osteogenic precursor cells cause ____ to occur
8. Next formation of _____ occurs
9. Following ______ formation begins

A
  1. Cartilage
  2. Mineralized collar
  3. Undergo hypertrophy
  4. VEGF
  5. Blood vessels
  6. Osteogenic precursor cells & Osteoclasts
  7. Resorb; osteogenesis
  8. Marrow cavity
  9. Trabecular bone
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32
Q

The area between two bony regions that is left with cartilage

A

Growth plate

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33
Q

During endochondral bone formation, the secondary ossification center leads to:

A

A second are of bone formation on either end of the bone

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34
Q

The growth plate is extremely important in:

A

Longitudinal bone growth

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35
Q

Around what age does fusion of the growth plate occur?

A

Age 14-20

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36
Q

When fusion of the growth plate occurs what is essentially happening and what does this cause?

A

Cartilage dissapears; bone is no longer able to grow

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37
Q

What factors play a role in the timing of fusion of the growth plate:

A

Age & gender

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38
Q

During intramembranous bone formation-

______ cells condense to produce _____

A

Mesenchymal cells
Osteoblasts

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39
Q

What does intramembranous bone formation lack when compared to endochondral bone formation?

A

A cartilage intermediate

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40
Q

During intramembranous bone formation-

Following the mesenchymal cell condensation and resulting osteoblast production, what do the osteoblasts do?

A

Deposit osteoid bone matrix

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41
Q

The osteoid bone matrix deposited by the osteoblasts is:

A

Unmineralized

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42
Q

During intramembranous bone formation-

Following the deposition of osteoid matrix what happens?

A

The osteoid matrix calcifies & osteoblasts become arranged along the calcified region of the matrix

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43
Q

During intramembranous bone formation-

What happens to some of the osteoblasts lining the calcified region of the osteoid matrix?

A

They get trapped in the bone matrix

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44
Q

During intramembranous bone formation-

When osteoblasts get trapped within the bone matrix they ultimately become:

A

Osteocytes

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45
Q

First type of bone produced developmentally:

A

Woven bone

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46
Q

Type of bone that is considered immature bone

A

Woven bone

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47
Q

Primary bone

A

Woven bone

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48
Q

Bone that is produced when osteoblasts need to form bone rapidly

A

woven bone

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49
Q

In what situations would osteoblasts may need to form bone rapidly: (3)

A

Embryonic development
Fracture healing
Disease states

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50
Q

What is an example of a disease state that may require rapid bone formation?

A

Paget’s syndrome

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51
Q

Immature woven bone will later be:

A

Remodeled and replaced with lamellar bone

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52
Q

Secondary bone

A

Lamellar bone

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53
Q

Type of bone that is considered mature

A

Lamellar bone

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54
Q

Name the type of bone this describes:

Disorganized in structure

A

Woven bone

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55
Q

Name the type of bone this describes:

Randomly oriented collagen fibers

A

Woven bone

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56
Q

Name the type of bone this describes:

Mechanically stronger

A

Lamellar bone

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57
Q

Name the type of bone this describes:

Highly organized

A

Lamellar bone

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58
Q

Name the type of bone this describes:

More birefringence with polarized light

A

Lamellar bone

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59
Q

Name the type of bone this describes:

Lower birefringence with polarized light

A

Woven bone

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60
Q

Name the type of bone this describes:

Collagen fibers oriented parallel

A

Lamellar bone

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61
Q

Name the type of bone this describes:

Increased cell density

A

Woven bone

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62
Q

Name the type of bone this describes:

Reduced mineral content

A

Woven bone

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63
Q

Name the type of bone this describes:

Contain concentrical arrangements around central canal that houses the blood vessels and nerves

A

Lamellar bone

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64
Q

Name the type of bone this describes:

Contain Haversian canals

A

Lamellar bone

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65
Q

Lamellar bone can further be classified into:

A

Compact (cortical) bone
Cancellous (trabecular/spongy) bone

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66
Q

Lamellar bone that is classified as compact is also referred to as:

A

Cortical

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67
Q

Lamellar bone that is classified as cancellous is also referred to as:

A

Trabecular/spongy

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68
Q

Refers to the bone that you find in the cortex, that is full of haversian systems and thick concentric rings of bone:

A

Compact bone

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69
Q

Bone that tends to be more commonly found in the marrow cavity where its also providing a support role but there are plenty of gaps in between the bony trabeculae that allow for space for the marrow to reside:

A

Cancellous bone

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70
Q

The gaps in between the bony trabeculae of cancellous bone allow space for:

A

Marrow to reside

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71
Q

What would happen if the bony trabeculae was filled with compact bone?

A

It would be extremely heavy

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72
Q

Labels the following image

A

1- bone marrow
2- blood vessels
3- compact bone
4- spongy bone

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73
Q

Label the following image

A

1- canaliculi
2- osteocyte lacunae
3- osteon
4- Haversian canals
5- osteon

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74
Q

Giant multinucleated cells that form from the fusion of monocyte/macrophage lineage

A

Osteoclasts

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75
Q

What is the origin of osteoclasts:

A

Hemopoietic origin

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76
Q

What do osteoclasts do?

A

Resorb bone

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77
Q

How do osteoclasts resorb bone?

A

By producing acid and enzymes that digest away and remove bone

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78
Q

Cuboidal cells located on the surface of bone which secrete collagen & other matrix components to generate the bone matrix

A

Osteoblasts

79
Q

Osteoblasts that become trapped/embedded on the surface of bone to form a network

A

Osteocytes

80
Q

Osteocytes look similar in appearance to:

A

Neurons

81
Q

Osteocytes are connected to eachother and other:

A

Osteoblasts

82
Q

Label the types of cells in the image

A

1- osteoclasts
2- osteoblasts
3- osteocytes

83
Q

Determine the types of bone cells in the following image:

A

1- osteoclasts
2- osteoblasts
3- osteocytes

84
Q

What types of cells all differentiate from a common mesenchymal precursor? (4)

A

1- osteoblasts
2- chondrocytes
3- myoblasts
4- adipocytes

85
Q

Type of cell condensation that pattern where the bone is going to form

A

Mesenchymal

86
Q

Cells that dependent on what signals they are subjected to controls what will differentiate into (many options)

A

Multipotent

87
Q

Because mesenchymal cells can give rise to numerous different cell types they are classified as:

A

Multipotent

88
Q

When a mesenchymal cell receives signals to differentiate into a myoblast- it will ultimately give rise to:

A

Myocytes

89
Q

When a mesenchymal cell receives signals to differentiate into a pre-adipocyte- it will ultimately give rise to:

A

Adipocytes

90
Q

When a mesenchymal cell receives signals to differentiate into a pre chondrocytes- it will ultimately give rise to:

A

Hypertrophic chondrocytes

91
Q

When a mesenchymal cell receives signals to differentiate into a a pre-osteoblast- it will ultimately give rise to:

A

Osteoblasts

92
Q

Bone forming cells

A

Osteoblasts

93
Q

Osteoblasts are derived from:

A

Mesenchymal stem cells

94
Q

Describe shape of osteoblasts

A

Plump, cuboidal

95
Q

What specific extracellular matrix protein do osteoblasts produce large amounts of:

A

Collagen type I

96
Q

Lifespan of osteoblasts:

A

Weeks

97
Q

What happens when osteoblasts reach the end of their lifespan?

A

Terminal differentiation to become an osteocyte or cell death

98
Q

What are the osteoblast marker proteins are transcription factors (2):

A

Runx2
Osterix

99
Q

What osteoblast marker protein is an enzyme:

A

Alkaline phosphatase

100
Q

What osteoblast marker proteins are extracellular matrix proteins: (4)

A

Type I collagen
Osteopontin
Osteocalcin
Bone sialoprotein (BSP)

101
Q

When we refer to specific proteins as osteoblasts marker proteins- what does this mean?

A

These are the genes that differentiate osteoblasts from other types of cells

102
Q

Proteins that regulate gene expression

A

Transcription factors

103
Q

An enzyme expressed by osteoclasts that is very important in the mineralization process:

A

Alkaline phosphatase

104
Q

Key transcriptional regulators of osteoblast differentiation:

It is imperative that the RUNX2, osterix, & beta-catenin

A

at the appropriate time in an appropriate amount

105
Q

Key transcriptional regulators of osteoblast differentiation:

What transcriptional regulator functions to push the osteogenic precursor to the immature osteoblast?

A

RUNX2
Beta-catenin

106
Q

Key transcriptional regulators of osteoblast differentiation:

If Beta-catenin acts on the mesenchymal cells too early in proliferation what will result?

A

Inhibit the transition from mesenchymal stem cells to osteochondrogenic precursors

107
Q

Key transcriptional regulators of osteoblast differentiation:

What transcriptional regulators function to push the immature osteoblast to the mature (matrix producing) osteoblast during the maturation stage?

A

Osterix & Beta-catenin

108
Q

Key transcriptional regulators of osteoblast differentiation:

If RUNX2 is acts on the immature osteoblast for too long during the maturation phase what is the result?

A

It will prevent further differentiation

109
Q

Key transcriptional regulators of osteoblast differentiation:

What transcription factor is responsible for the transition from mature (matrix producing) osteoblast to the terminally differentiated states?

A

Beta-catenin

110
Q

What are the terminally different states the osteoblast?

A

Osteocyte
Lining cell
Apoptosis

111
Q
A
112
Q

Label the boxes with the appropriate TF factors acting at the various stages of osteoblast differentiation

A
  1. RUNX2 & Beta-Catenin
  2. Osterix & Beta-Catenin
  3. Beta-catenin
113
Q

Label the following stages of osteoblast differentiation

A
  1. Proliferation
  2. Maturation
  3. Terminal differentiation
114
Q

Label the following types of cells in the various state os osteoblast differentiation:

A
  1. Mesenchymal stem cells
  2. Osteochondrogenic precursors
  3. Immature osteoblast
  4. Mature osteoblast
  5. Differentiated cell states- osteocytes, lining cells, apoptosis
115
Q

Beta-catenin is involved in:

A

The WNT signaling pathway

116
Q

_____ comes on at an early stage pushing the precursors from the osteogenic to the osteoblastic phenotype

A

RUNX2

117
Q

____ comes on at a later stage pushing an immature osteoblast to a mature osteoblast

A

Osterix

118
Q

If take a mouse & KO the RUNX2 gene- you end up with a mouse that has:

A

an only cartilaginous skeleton that will not mineralize

119
Q

In humans with complete KO of RUNX2- this will result in:

A

a fetus that is not compatible with life

120
Q

A heterozygous mutation of RUNX2 in humans results in:

A

Cleidocranial dysplasia (CCD)

121
Q

RUNX2 is a master transcription factor essential for:

A

bone & tooth development

122
Q

Cleidocranial dysplasia is caused by what type of mutation?

A

Autosomal dominant

123
Q

CCD results from ______ in RUNX2

A

haploinsufficiency

124
Q

Inactivating mutation/deletion in one allele

A

haploinsifficiency

125
Q

Disease characterized by delayed ossification of midline structures of the body (especially in membranous bone)

A

Cleidocranial dysplasia

126
Q

In CCD:

  1. _____ are partly or completely missing
  2. late closing of _____
  3. describe teeth:
  4. ____ mandible due to ____ of maxilla
A
  1. clavicles
  2. fontanelle
  3. supernumerary teeth
  4. prognathic (protruding); hypoplasia
127
Q

what transcription factor is downstream of RUNX2

A

Osterix

128
Q

What transcription factor does RUNX2 produce?

A

osterix

129
Q

Mice lacking osterix have:

A

impaired osteoblast formation

130
Q

Gene name for osterix

A

SP7

131
Q

Osterix controls expression of what osteoblast genes?

A

Type I Collagen
Osteocalcin
Osteopontin

132
Q

Human mutations in SP7 (osterix) are associated with:

A

Osteogenesis imperfecta type xii

133
Q

What are two important key signaling pathways that regulate osteoblast differentiation:

A

BMPs
WNT/Beta-catenin signaling

134
Q

What important key signaling pathway comes first when regulation osteoblast differentiation?

A

BMP2,7

135
Q

If signaling of WNT/Beta-catenin pathways occurs too early what will occur?

A

Inhibit the mesenchymal cells from differentiation into osteechondrogenic precurosurs

136
Q

Originally purified from bone extracts that induce bone formation when implanted in muscle (ectopic bone assay)

A

BMPs

137
Q

BMPs required for ______ of adult bone homeostasis

A

skeletal development/maintenance

138
Q

BMPs promote differentiation from:

A

early osteoprogenitor cells

139
Q

Important in fracture healing

A

BMPs

140
Q

KO of specific BMPs leads to

A

skeletal defects

141
Q

Naturally occurring mutations in BMPs or their receptors result in:

A

inherited skeletal disorders in humans

142
Q

A disease characterized by heterotopic bone formation:

A

Fibrodyplasia ossificans progressiva

143
Q

Stone man syndrome

A

Fibrodysplasia ossificans progressiva

144
Q

Where does the bone form in fibrodysplasia ossificans progressiva?

A

soft tissues

145
Q

In FOP cases surgical treatment is not an option because?

A

Bone forms in response to tissue trauma

146
Q

what mutation in what gene causes fibrodysplasia ossificans progressiva

A

Mutation in BMP type I receptor (single amino acid mutation)
gene: ACVR1

147
Q

The mutation involved in FOP causes mild _______ & _______ with BMP ligand binding and overreaction with BMP ligand binding

A

constitutive activation

148
Q

In addition to the constitutive activation & over activation with BMP ligand binding in FOP, there is also acquired responsiveness to:

A

Activin A

149
Q

What potential treatments have been looked into regarding FOP?

A

antibodies against activin A & Kinase inhibitors selective for mutant receptor

150
Q

WNT/Beta-catenin signaling pathway:

In normal circumstances when there is no WNT to stimulate its receptor, the Beta-catenin will be:

A

phosphorylated by GSK-3-Beta

151
Q

WNT/Beta-catenin signaling pathway:

When Beta-Catenin is phosphorylated by GSK-3-Beta what results:

A

Beta-catenin will go to be degraded in cell

152
Q

WNT/Beta-catenin signaling pathway:

Describe the receptor for the WNT ligand:

A

LRP5 + LRP6 + Frizzled

153
Q

WNT/Beta-catenin signaling pathway:

When WNT comes in & binds its receptor complex, that will then come in and phosphorylate the GSK-3-beta which will then:

A

release the beta-catenin

154
Q

WNT/Beta-catenin signaling pathway:

When the GSK-3-Beta releases the B-catenin, it allows for the beta-catenin to go to the _____ & interact with a protein called _____ & then initiate ______

A

nucleus
TCF
Gene transcription

155
Q

WNT/Beta-catenin signaling pathway:

When the Beta-catenin is able to get inside the nucleus to interact with TCF & initiate gene transcription it will ultimately lead to:

A

bone formation (osteogenesis)

156
Q

Signaling pathway important in determining bone mass

A

Wnt-B-catenin pathway

157
Q

Activating mutations in Lrp5 leads to:

A

High bone mass in humans

158
Q

Inactivating mutations of Lrp5 leads to:

A

Low bone mass in humans

159
Q

_____ mutations in Lrp5 lead to high bone mass while ______ mutations in Lrp5 lead to low bone mass

A

activating
inactivating

160
Q

Mechanism of bone mineralization:

The first phase of mineralization is initiated by:

A

Matrix vesicles released by the cell surface of mineralizing cell types

161
Q

Mechanism of bone mineralization:

The second phase of mineralization involves:

A

Propogation of mineralization on collagen fibers

162
Q

Mechanism of bone mineralization:

Extracellular membrane bound vesicles produced by osteoclasts:

A

matrix vesicles

163
Q

Mechanism of bone mineralization:

The size of matrix vesicles is:

A

30-1000nm in diameter

164
Q

Mechanism of bone mineralization:

What is located in the membrane of the matrix vesicles? (3)

A
  1. calcium transporters
  2. phosphate transporters
  3. enzymes that generate phosphate
165
Q

Mechanism of bone mineralization:

What do the matrix vesicles create in the second phase (propogation of mineralization on collagen fibers)

A

seating crystals- formed by calcium & phosphate

166
Q

Mechanism of bone mineralization:

The seating crystals fill the matrix vesicle & eventually ______

A

puncture it

167
Q

Mechanism of bone mineralization:

After puncturing the matrix vesicles, the crystal then act as ________

A

nucleation sites (seed points)

168
Q

Mechanism of bone mineralization:

when acting as nucleation sites (following the puncturing of the matrix vesicles) this is allowing for:

A

further propagation of mineral deposition on collagen

169
Q

Enzyme highly expressed in osteoblasts/odontoblasts

A

alkaline phosphatase

170
Q

Enzyme that is a marker gene for mature osteoblasts & plays a role in bone mineralization by hydrolyzing pyrophosphate (PPI) a natural inhibitor mineralization

A

alkaline phosphatase

171
Q

When alkaline phosphatase hydrolyzes PPI this results in:

A

Increased local concentration of phosphate
Promotes mineralization

172
Q

Mice lacking alkaline phosphatase gene (TNAP) have:

A

impaired mineralization

173
Q

Humans with a mutation in the gene for alkaline phosphatase (TNSALP) this is association with _______ a disease of impaired mineralization

A

hypophosphatasia

174
Q

a disease characterized by impaired mineralization due to mutation in gene for alkaline phosphatase

A

hypophosphatasia

175
Q

Rare heritable rickets/osteomalacia is caused by a mutation in:

A

Hypophosphatasia

176
Q

They type of mutation most common in the rare heritable rickets/osteomalacia (HPP) is due to

A

missense mutation in human alkaline phosphatase gene

177
Q

The mutation in alkaline phosphatase gene in HPP render:

A

reduced activity of alkaline phosphatase

178
Q

Symptoms of what disease include: impaired mineralization of skeleton/dentition, leg bowing, rachitic rosary, early tooth loss, waddling gait, muscle weakness & seizures

A

Hypophosphatasia (rare heritable rickets/osteomalacia)

179
Q

Hypophosphatasia varies in severity from perinatal-lethal to adult mild onset forms only affecting the dentition. The varying severity is dependent on:

A

degree of loss of function of alkaline phosphatase

180
Q

Treatments for hypophosphatasia:

A

Bone targeted enzyme replacement therapy TNSALP

181
Q

In the mineralization process, mutations in ENPP1 are associated with:

A

syndrome of sponteneous infantile arterial & periarticular calcification

182
Q

In the mineralization process, mutations ion TNSALP are associated with:

A

Hypophosphatasia

183
Q

In the mineralization process, mutations in Anx5 don’t abnormal skeletal development. This is likely due to:

A

compensation from other annexing family members

184
Q

PHOSPHO1 deletion in mice causes:

A

impaired mineralization, including in MV

185
Q

Key roles of osteocytes:

A

1- regulation of activity of osteoblast & osteoclast
2- major role in mechanosensation
3- role in phosphate homeostasis
4- endocrine function

186
Q

Make up over 90% of all been cells

A

osteocytes

187
Q

Lifespan of osteocytes:

A

decades

188
Q

No master transcription factors have been discovered in osteocytes but _____ may play a role:

A

Mef2c

189
Q

E11/gp38 are markers of:

A

early osteocyte

190
Q

SOST (Sclerostin) is a marker of:

A

late/mature osteocyte

191
Q

Highly expressed by osteocytes & acts as a naturally occurring inhibitor of bone formation by inhibiting the WNT-beta catenin signaling

A

sclerostin

192
Q

Currently a target for the development of bone metabolic drugs

A

sclerostin

193
Q

If a drug was found to inhibit sclerotin it would result in:

A

promotion of bone formation

Applied Biochemistry (18 decks)

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