Developmental Genetics Flashcards
what does the molecular basis of development involve
establishment and maintenance of different patterns of gene expression cells differentiate
what is a homeotic mutation?
what are they useful in?
a mutation that causes a body part to develop in the wrong place
what is totipotent?
vertebrate example?
-capable of forming any tissue or cell type
-EX. embryonic stem cells
what does differentiated mean in cells?
taking on different morphologies and physiological activities
what is pluripotent? what are its characteristics?
cells that give rise to many but not all cell types
-found in a number of tissues
-retain ability to develop into range of specialized cells
-can replenish what is lost
3 differential directions mesenchymal cells can go
adipocyte
chondrocyte(cartilage)
osteocyte(bone)
how does a cell know its relative position in the embryo?
positional information: cues/signals that inform the cell
what is a morphogen?
substances whose presence in differing concentrations directs developmental fates
induction vs inhibition? what is the organizer?
Induction: when a cell induces its neighbor to acquire a certain fate
Inhibition: a cell prevents its neighbor from adopting a certain fate
Organizer: the transplanted region
why are drosophila so well understood/studied
-short life cycle
-short embryogenesis
how many larval stages do drosophila have? what are they called?
-3 larval stages
-called instars
what is syncytium and syncytium blastoderm
Syncytium: multinucleated egg made from nuclear divisions in early embryogenesis
Syncytium Blastoderm: somatic cells undergoing four rounds of mitosis at embryo periphery, contains 6,000 nuclei
how many thoracic and abdominal segments do drosophila have?
Thoracic: 3
Abdomen: 8
what is the role of the cytoskeleton?
provides “highway” to move molecules to different parts of the embryo
what motor moves the vesicle along the microtubule
kinesin
5 classes of mutations for drosophila and their effects
Coordinate genes: affect entire pole of larva
Gap genes: mutants missing large contiguous section
Pair-rule gene: mutants missing part of adjacent segment pairs in alternating patterns
Segment Polarity gene: defects in patterning with each of the 14 segments
Homeotic genes: defects alter identity of 1+ segments
which gene plays a major role in establishing the anterior posterior axis
bicoid gene
what happens with a loss of function mutant? what are they replaced with?
results in loss of anterior structures
-replaced by mirror image duplication of posterior region
genes that establish A-P positional information? how do they interact?
Bicoid: activates hunchback at anterior end
Hunchback: gap gene, diffuse expression
what represses hunchback in posterior
maternal gene nanos
what genes activates/represses kruppel
Activates: moderate levels of bicoid
Represses: high concentrations of hunchback, knirps, giant
what are the ANT-C and BX-C? what are they responsible for?
ANT-C: antennapedia complex, determines segment identity in head and anterior thorax
BX-C: bithorax complex, leads to altered positions of organs and body structures in homeotic mutants
what is a homeobox? what are the genes of the complexes called?
a shared conserved sequence of 180 nucleotides in proteins encoded by all 8 genes in drosophila
what 5 hox genes are expressed in the limb bud? which hox gene goes with which digit?
thumb: hoxd9
pointer: hoxd9, 10
middle: hoxd9, 10, 11
index: hoxd9, 10, 11, 12
pinky: hoxd9, 10, 11, 12, 13
