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C1-50 Developmental Genetics
Ursin Lecture
14
Biochemistry
Professional
10/04/2010

Additional Biochemistry Flashcards

 


 

Cards

Term

 

 

 

Teratogen

Definition

Any agent that can produce a malformation or raise the population incidence of a malformation

Acts directly and transiently on developing embryonic tissue

Term




Syndrome

Definition

a pattern of multiple primary malformations or defects with a single underlying cause / etiologic agent causes multiple abnormalities in parallel

Term

 

 

 

Smith-Lemli-Opitz Syndrome

Definition

Example of overlap between a metabolic and developmental pathway (SHH signal transduction pathway)

Cholesterol is involved in cleavage of sonic hedgehog (SHH), a secreted ligand, to N-SHH and potentially to the interaction of SHH with its receptor, Patched

Term




Association

 

Definition

A group of abnormalities of unknown etiology and pathogenesis that is seen together more often than would be expected by chance.


ex. VATERR Association

 

Term




VATERR Association

Definition

V – vertebral defects
A – anal atresia +/- fistula
T-E fistula with esophageal atresia
R – radial dysplasia:
thumb or radial hypoplasia
preaxial polydactyly
syndactyly
R – renal anomaly

   Cardiac defects, single umbilical artery, and prenatal growth deficiency  are also nonrandom features

Term

 

 

Sequence

Definition

localized anomaly that causes multiple pleitropic defects as secondary effects of the primary anomaly - a cascade of subsequent defects

ex Robin sequence

Heterogeneous
Restricted mandibular growth causes posterior displacement of the tongue and  interferes with palatal closure
Results in  U-shaped cleft palate
Term

 

 

 

Developmental biology

Definition

the genetic, biochemical, cellular, and physiological processes whereby a one-cell embryo gives rise to an entire organism

 

Differentiation: process whereby one or more cells acquire a specific pattern of gene and protein expression characteristic of a particular cell type or tissue.
Morphogenesis: process whereby changes in cell shape, adhesion, movement, proliferation, and/or death give rise to a three-dimensional structure.

Term

 

 

 

Implantation

Definition

-between days 7-12 after fertilization

Term



Gastrulation

Definition

- three primary germ layers arise from the epiblast


Mosaic development –fate of a particular cell is specified independently of its environment (embryo can no longer easily compensate for damaged or lost cells)


Organogenesis begins after gastrulation
(wks 4-8)

Term



Four major families of signaling molecules

Definition

Fibroblast Growth Factors (FGF)
- about 2 dozen exist and function in angiogenesis, mesoderm formation, axon extension
Hedgehog Proteins
– three homologs ; sonic, desert, indian – induce particular cell types and create boundaries between tissues
Wingless (Wnt) Family Proteins
-family of 15 cysteine-rich glycoproteins – functions: dorsal cells of somites to become muscle, polarity of limbs, GU system
Transforming Growth Factor B (TGF-B)
30 members – regulate formation of extracellular matrix between cells and cell division

Term



HOX (homeobox) genes

Definition

Encode a class of transcription factors
Determine regional identity along anterior-posterior axis
-HOXA and HOXD clusters
-Regional identity along axis of developing limb

Term




PAX3

Definition

9 human genes in the PAX family of transcription factors
PAX3  - expressed in CNS during neural tube closure and later in the somites
Neural crest cells –
migrate throughout the embryo
differentiate into many cell types – melanocytes, enteric and peripheral ganglia, Schwann cells …, and populate tissues including the facial bones and the cardiac outflow tracks

Term




Waardenberg syndrome  Type I

Definition

Mutation of PAX3
Heterozygosity for PAX3 loss-of-function mut results in a reduction of neural crest derivatives such as melanocytes in hair, eyes, and inner ear
White forelock
Pale colored eyes/ heterochromatic irides
Sensorineural deafness

Dystopia canthorum
outward displacement of the inner canthus
Upper extremity defect –
occasional

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