10/18: Development Flashcards

1
Q

Genes provide the ___________

A

Blueprint

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2
Q

What does the blueprint ensure

A

We have integrated maxilla, mandible and oronasal cavity

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3
Q

What does the complement of RNA and protein expressed define

A

The identity of each cell, its appearance and behavior

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4
Q

Where do cells receive and process information from?

A

Their surroundings - growth factors, hormones, force/tension, nutrients. oxygen levels, etc

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5
Q

What do these things that cells receive and process modulate?

A

Gene expression, thus allowing the cell to adapt and take on new properties/behaviors

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6
Q

What are multicellular organisms enriched in?

A

Proteins mediating cell communication

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7
Q

These factors have been highly __________________

A

Conserved throughout evolution

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8
Q

What is Wnt signaling

A

Secreted Wnt ligands bind to cell surface receptors, which stimulates specific gene expression

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9
Q

_____ main cellular processes are employed during embryogenesis

A

4
Cell proliferation
Cell specialization
Cell interaction
Cell movement

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10
Q

What is the fifth process and what is it utilized for?

A

programmed cell death - used to “fine tune” development

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11
Q

Homeobox code

A

Patterned expression of an ‘ancient’ family of transcription factors known as HOX proteins

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12
Q

Expressions of the Hox genes is colinear with?

A

Order on the chromosome

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13
Q

What is homeotic transformation?

A

Replacement of one body part with another

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14
Q

What did Ed lewis discover

A

Hox genes are responsible for establishing the fate of individual segments

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15
Q

What does the hox gene organization and expression across species determine?

A

Regional identity in the body plan

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16
Q

Where are mouse complexes located?

A

On 4 different chromsoomes

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17
Q

What does the pattern of expression of each gene follow?

A

Head to tail and order on chromosome

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18
Q

All aspects of positional identity in vertebrates is established by?

A

Hox genes EXCEPT THE FACE which has its own homeobox-related code

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19
Q

What distances to morphogen gradients act over

A

Many cell distances
Nearby cells -> high levels
Distanc cells -> low levels (but over time, receive more)

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20
Q

Morphogen

A

Signaling factor that directs cell fate (tissue development) at a distance from their source

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21
Q

______-dependent and ________-dependent effects on gene expression

A

Time; duration

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22
Q

What are examples of inductive signaling as mechanisms of morphogenesis?

A
  1. Establishing symetry and form in the embryo
  2. Craniofacial growth and patterning
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23
Q

What axes are craniofacial complexes defined by?

A

Left-right
Dorsal-ventral
Anterior-posterior

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24
Q

Clinical treatments always consider:

A

Form (tooth shape, spacing, number, cusp pattern)
Symmetry (because they are critical for function and esthetics)

25
Q

What is the dorsal ventral axis apparent by?

A

Blastocyst stage

26
Q

What occurs in the first 3 weeks?

A

Morula (32 cells) to blastocyst (64 cells) transition is the first sign of cell fate change/commitment

27
Q

What is determined at start of week 3?

A

Anterior-posterior axis [head-tail] and left right axis, with appearance of the primitive streal

28
Q

Primitive streak

A

A change in cell behavior/fate

29
Q

Where do epiblastic cells converge at?

A

Midline and ingress (marks posterior end)

30
Q

Explain the process of cells of the epiblast migrating

A

Cells of the epiblast migrate “through” primitive streak to form mesoderm and embryonic (gut) endoderm

31
Q

What is the process that forms the mesoderm?

A

Epithelial to mesenchyme transformation (EMT)

32
Q

The movement of epiblasts (ectoderm) forms

A

embryonic endoderm

33
Q

What does the node act as

A

a signaling center

34
Q

Factors that are produced by cells at the node induce and specify:

A

fate of the mesoderm as it is formed

35
Q

What does the node generate

A

asymmetry in a previously symmetrical embryo

36
Q

Nodal cells each have one __________

A

motile cilium

37
Q

What is a cilium

A

a membrane covered extension from the cell that has a microtubule cytoskeleton core which helps define the properties of the cilium: mechanosensory or rotational

38
Q

Nodal cilia have a rotational _______

A

beat (for a few hours only)

39
Q

What does the rotational beat generate

A

leftward flow, resulting in asymmetric distribution of morphogens/growth factors

40
Q

What morphogenic factors around the node are expressed and how

A

asymmetrically ; SHH, BMP4, FGF8

41
Q

What does the asymmetric expression initiate?

A

Cascade of gene expression to promote asymmetric specialization/commitment of mesoderm

42
Q

What is the evolutionarily conserved mechanism in vertebrates?

A

Reproducible morphological and functional asymmetries in nearly all internal organs

43
Q

In mice ~______ genes affect L-R asymmetry and what does this affect

A

27; cilia function, gene expression around node changes

44
Q

What is the rapid outgrowth of the early facial tissue driven by?

A

The proliferation and ventral migration of cells originating from the ‘crests’ of the forming neural tube

45
Q

What do neural crest cells arise by

A

Epithelial-mesenchymal transformation (EMT)

46
Q

What is NCC arising anaologous to?

A

Generation of the third germ layer (mesoderm)

47
Q

What do cranial neural crest cells differentiate into?

A

Wide variety of cell types/tissues
‘stem cell-like’
unique developmental potential

48
Q

What defines distinct populations of CNCC and their route of migration into early facial tissue

A

Hindbrain segments (patterned by hox gene expression)

49
Q

What do cranial neural crest cells (CNCC) primarily determine?

A

Facial form/shape

50
Q

What is treacher-collins syndrome?

A

Defects in polymerase I subunits (Required for synthesis of rRNAs) and TCOF1

51
Q

Transplanted ectoderm retains ________ pattern of expression from originating tissue

A

FGF8/SHH

52
Q

What can secreted factors from the FEZ direct

A

outgrowth of the underlying CNCC and determines D-V pattern on the FNP

53
Q

What does precise shape depend upon

A

pattern information inherent in the neural crest

54
Q

Embryogenesis is a __________ process

A

generative (not descriptive)

55
Q

What does cellular communication with neighboring and distant cells/tissues coordinate?

A

Different aspects of development

56
Q

What can malformation and normal phenotypic variation result from?

A
  • single changes in gene sequences
  • combinations of normal gene variants
  • changes in the environment to which cells respond
57
Q

The control of gene expression during development is __________ or ___________

A

hierarchial or sequential

58
Q
A