molecular genetics and early embryonic development Flashcards

1
Q

Paradigm of Development

A

In every species and at every level of
organization, complex structures are made
by repeating a few basic themes with
variations.

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2
Q

Stages of Embryonic Development

A

dif
growth
patterning

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3
Q

differentiation

A

cells begin to form specific and specialized structures.

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4
Q

growth

A

cell divisions that form more cells with identical functions as the parental cell.

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5
Q

patterning, deminsions?

A

cells produced by cleavage get organized into layers and groups of cell masses through what is known as gastrulation.

• Patterning needs to occur in 3 dimensions
– Anterior-Posterior (top-bottom)
– Dorsal-Ventral (left-right)
– Proximal-Distal (front-back)

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6
Q

Craniofacial Anomalies Account for? why?

A

1/3 all congenital defects

development occurs 3-8wks, most susceptible time for malformations

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7
Q

4 Important Concepts of Embryonic Development

A
  • Universal Mechanisms of Animal Development
  • Proteins can be substituted across species
  • Inductive signaling
  • Regional Determination
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8
Q

Universal Mechanisms of Animal Development

A

Multicellular animals are enriched in proteins mediating cell interactions and gene regulation
the 5 main signaling paths: RTK, TGFB, Wnt, Hedgehog, Notch

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9
Q

Hierarchical Gene Control diagram

A
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10
Q

protein substitution

A
  • Multicellular organisms are enriched in proteins mediating cell interactions and gene regulation, could be different protein among species but sam role
  • Regulatory DNA defines the development program=promoter region, etc.
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11
Q

Important Concepts of Embryonic Development: types of divisions? signaling?

A
  • Asymmetric versus Symmetric Cell Division

* Inductive Signaling/ Morphogens

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12
Q

Asymmetric vs. Symmetric Division

A

both usually with equal distribution of DNA but the distribution of cytoplasmic contents may vary

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13
Q

Inductive Signaling, components?

could lead to?

A
  • Starting Point (cell or cell cluster)
  • Cell – cell signaling
  • Cell signaling cascades
  • Acts over great distances

produces a gradient of factors to cause the differentiation of nearby cells by altering gene expression, can lead to sequential induction

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14
Q

Sequential Induction

A

cells formed via inductive signaling may produce new signals that can then lead to the differentiation of new cell types

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15
Q

Morphogen Gradients

A

could be inducer or inhibitor gradient

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16
Q

Gastrulation simple definiton

A

Early developmental process in which the embryo (week 3 in humans) transforms from a single cell layer (blastula) into the three primary germ layers:

17
Q

Early Embryonic Development/ formation of the primitive streak

A

primitive streak will form giving rise to hensons node; this will define the 3 planes of development (A-P, D-V, M-L)
cells will migrate in and form the various cell layers; endo, meso and ectoderm
(endo formed at hypoblast and ecto formed at exterior with the meso forming between these)

18
Q

Regional Determination

A

cells will commit to certain cascades and form particular structures in different regions, can be transplanted but will still form the structure it was committed to

19
Q

Craniofacial Syndromes
how many?
infant mortality?
howmman y births exhibit these?

A
  • > 700 distinct syndromes
  • Significant cause of infant mortality
  • 3% of all live births exhibit some form of minor or major abnormality
20
Q

Craniofacial Development events

A
  • Neural tube development and closure
  • Formation of ectoderm, somites, mesoderm and other cell masses
  • Neural crest cell development, differentiation and migration
  • Tissue-tissue interactions
  • Tissue specific patterns of gene expression
  • Reciprocal Induction
  • Growth and mineralization of bones and teeth
  • Neural development
  • Muscle development
21
Q

signals of the embryo directionality

A

cells may produce ventralizing, dorsalizing and lateralizing signals to form structures

22
Q

Paraxial mesoderm development and differentiation pathway

A
23
Q

Neural Crest Cells
origin?
stemness?
migration?

A

Embryonic cell population that is localized between the developing neural tube and the epidermis. (adult ones possible)
• Some neural crest cell exhibit “stemness” in that they can give rise to multiple differentiated cell types.
• In the formation of the craniofacial structures (and many other structures) the neural crest cells migrate through restricted pathways to form the developing structures.
• Cell migration is a tightly regulated process and the NCCs receive cues such as morphogens and growth factors that restrict their movement and determine fate.

24
Q

Neural Crest Cells and the Skull, driven by what pathways?

A

skull formed from these cells (pharyngeal arches)

driven by the 5 major signaling pathways

25
Q

Tooth Development basic

A

ectoderm and mesenchyme interact with one another, invagination into the mesenchyme and ecto produces cell signals to cause release of various factors that can then go back and forth between the two layers leading to tooth formation (GF, TF, etc.)

26
Q

Genetics of Tooth Development (mutations)
number?
effects?
most common genetic diseases?

A
  • Over 300 genes identified that have mutations associated with tooth patterning, morphogenesis defects and cell differentiation defects
  • As a collective group craniofacial genetic diseases are the most common
27
Q

Genetic Diseases of the Dentition

A
Ectodermal dysplasias
Tooth Agenesis
Supernumerary Teeth
Cleft Lip/Palate (OMIM lists 565 entries)
Skeletal Diseases
28
Q

Types of Tooth Agenesis

A
  • Hypodontia: common types of tooth agenesis with only a few missing teeth
  • Oligodontia: more severe form of tooth agenesis with at least 6 missing teeth, excluding third molars
  • Anodontia: complete lack of teeth
  • Microdontia: one or more teeth appear smaller
  • Macrodontia: one or more teeth grow faster and exceed average size
29
Q

Key Signaling Pathways in Tooth Development, induced by?

A

involves the 5 major paths in which their activity is induced by the ecto/mesenchyme interactions

30
Q

Ectodermal dysplasias

A

– >100 different disorders
– Commonly involves one or more of teeth, nails, skin, sweat glands
and/or hair

31
Q

homeobox code and tooth formation

A

A homeobox code will drive the expression of singling factors for tooth formation and determine the class of tooth formed

32
Q

period of greastest risk of dev abnomrlaities?

A

3-8 weeks, embryogenesis