introduction Flashcards
can developmental biology continue in adult life?
yes, an example of this is neurogenesis in the brain
what can be used to study different gene expression patterns?
DNA microarray heat maps
what is the human connectome?
all of the connections in the human nervous system and how they vary between individuals
what are the three body axis?
- anterior/posterior
- dorsal/ventral
- left/right
what was observed in Wnt7a knock out mice?
their claws were in the top of their hands as correct localisation signal was interfered with
what are the three germ layers?
- ectoderm
- mesoderm
- endoderm
how can signals for a cell to differentiate be transmitted? (4)
- secreted
- pass through tiny nano-tubes from cell to cell
- cell bound
- gap junctions
what is asymmetric stem cell division?
mitotic division producing two daughters of different cellular fates
what is required for a cell to respond to a signal?
the correct receptor, looking for expression of this receptor can help model cell to cell interactions
what are morphogens? (giving one example of where it is observed in nature)
a molecule with concentration dependent effects
butterflies develop spots through morphogen gradients
what is the threshold concentration of a morphogen?
the concentration at which it triggers expression/repression
Who stated the French flag hypothesis?
Lewis Wolpert, 1969
what did the French flag hypothesis state?
different cells exposed to different concentrations of signal will have different gene expression and thus different cell fate
describe a finding that challenged the classical role of morphogens
- drosophila engineered to express only tethered Wnt (wingless)
- Wnt could not diffuse
- this was predicted to impare wing development but this was not the case
proposed that signal was spread through cell division
what factors mediate embryo morphogenesis (shape change)? (5)
- cytokines
- signalling
- cell movement
- cell death
- space/tube formation
give an example of how cell death aids morphogenesis
TGF-β is required for programmed cell death in interdigital webs of the developing mouse limb
give an example of morphogenesis in the developing embryo
neural tube closure
neural plate fold in to form the tube. changes in cells actin cytoskeleton causes tube to constrict.
what is spina bifida?
a neural tube defect where the spine does not develop properly leaving gaps in the spine, this is prone to infection.
caused by problems in Wnt signalling.
what is neural tube convergent extension?
Planar cell polarity signal ensure that as the neural tube is closing, it is also lengthening with the embryo.
certain signals, for example Wnt, are required for this and if this doesn’t occur spina bifida develops
give an example of how the scaling of an organism has been evolutionarily tweaked
crabs have scaled one claw to be larger than the other
how can the expression of mRNA for observed in a developing embryo?
FISH, can be used to observe how the cycling of mRNA expression is slowed down in a more mature embryo
what is a somite?
one of the paired segments along the neural tube of a vertebrate embryo, these are blocks of mesoderm
name so additional factors that can influence an embryo in utero (4)
- exogenous factors (e.g. toxins)
- congenital defects (e.g. club foot)
- syndromes
- epigenetics
give an example of how epigenetic inheritance can influence development
older fathers offspring tend to have a higher risk of developing autism (potentially epigenetic changes in older fathers sperm)
certain cells are signalled to in early development as progenitors of gametes. what occurs next?
primordial germ cells migrate through the gut to developing gonads, here they divide less often and then undergo meiosis
