Mechanisms of Development Flashcards
Is early or late embryonic development similar in vertebrates?
early
Does the amount of genes determine the complexity of an animal?
NO simple worms have just as much genes as us
what percent of genes do we share with mice?
92%
What is a homologous gene?
a gene similar in structure and evolutionary origin-function, to a gene in another species
What is genome equivalence?
genetic material is identical in every cell, but different cells express different sets
Nuclear transfer provided evidence for what?
that all cells contain the same genes
genomic equivalence
What are the four levels gene expression is regulated at?
- differential transcription
- selective nuclear RNA processing
- selective mRNA translation
- differential protein modification
What does this describe” one group of cell changes the behavior of an adjacent group of cells”
induction
The ability of a cell to respond to a signal is what term?
competence
The optic vesicle in the frog induces what structure in what tissue type?
induces lens formation in head ectoderm
How was it proven that only head ectoderm is competent to respond to optic vesicle?
optic vesicle placed in different location - ectoderm doesnt form lens
If the optic vesicle is removed, does the lens form?
noo0ope
What transcription factor is responsible for making head ectoderm competent
pax6
Autosomal dominant mutations in pax6 cause what disease with what symptoms in humans?
aniridia
affects the iris, intraocular P, lens, cornea, optic nerve
define these terms: juxtacrine, paracrine
juxtacrine - contact btwn inducing and responding cells
paracrine - diffusion of inducers
What are morphogens ?
paracrine signaling molecules that cause concentration dependent effects
How does TGF signal in the cell?
binds to receptor
signal is translocated to cytoplasm via smad proteins
phosphorylation turns smad on
gene transcription is altered
What is the pathway for SHH?
SHH binds patched
- inhibits smoothened
- turns on Gli factors which turn on gene expression
In the neural tube, describe where BMP, WNT, SHH are found?
BMP, WNT - dorsally - roof plate
SHH - ventrally - floor plate
What is the term for normal left right orientation?
situs solitus
What is the term for mirror left right reversal of all organs?
situs inversus
What is the term for disturbance of the left right axis in only a subset of organs?
situs ambiguus or heterotaxy
What are some examples of heterotaxy?
congenital heart defects
asplenia - right isomerism
polysplenia - left isomerism
malrotation of the intestine - volvulus
What is kartageners triad?
bronchiectasis
male infertility
50% with situs invertus
What is the ciliated organ of asymmetry?
the node
Where is nodal expressed in vertebrates?
on the left side of the lateral plate mesoderm
Describe the three effects of nodal
turns on:
nodal
Pitx2 - TF expressed on left side of heart, stomach, brain
Lefty - antagonist, keeps expression in check
