Gene Regulation Flashcards
three aspects of development
differentiation, morphogenesis, growth
differentiation
becoming a specialized cell
morphogenesis
organism develops shape
growth
cells divide or grow in size to make a bigger organism
How are cells made different from each other?
cell-cell signaling and asymmetric division of cytoplasmic determinants
cell-cell signaling
signaling molecules can be secreted to bind receptor on target cell or the signaling cell can have a molecule on the plasma membrane that binds adjacently to the target receptor
sequential induction
a series of inductions results in new types of cells
example of sequential induction
epiblast invaginates –> forms 3 layers –> mesoderm forms notochord –> notochord signals above ectoderm to form neuro-ectoderm
bicoid gradient
regulates the A/P patterning in drosophila –> lots of bicoid in anterior and none in posterior
asymmetric distribution
all of protein (determinants) segregate to one side so when cell divides, only one sister cell will get them
example of asymmetric distribution
P-granules in C.elegans all go to posterior before first division
totipotent
can produce all cells even placenta (fertilized egg)
pluripotent
can be all cells except placenta (embryonic stem cell)
multipotent
able to give rise to multiple cell types within the same lineage (hematopoietic stem cell)
stem cells
can divide and differentiate into other types of cells; multiple types
What controls the expression of genes?
epigenetics
determination vs. differentiation
if a posterior region is transplanted to anterior before determination, the posterior will develop as anterior; if it is transplanted after determination, it will differentiate into posterior but in an anterior region
ways to shape embryo
morphogenetic movements, changes in cell shape, cell matrix adhesions, intercellular adhesions, cell death, cell proliferation
When does neurulation begin?
when the notochord induces the formation of the CNS by signaling to the above ectoderm to form the neural plate
neuropores fail to close
spina bifida or anencephaly
neural tube fails to close
craniorachischisis
neuroectoderm
the region of ectoderm above the notochord –> will form the neural tube –> inhibits BMPs
neural tube
will later differentiate into the spinal cord and brain
ectoderm
signals to itself to remain ectoderm by secreting BMP4 and BMP7
neurulation
medial hinge point forms above notochord –> undergo apical constriction to form neural groove –> two dorsolateral hinge points also undergo apical constriction forming a tube –> fusion –> neural crest cells migrate away, epidermis becomes top layer
What level does neural tube folding begin?
around the level of the 4th somite at embryonic day 20
BMP inhibitors
chordin, noggin, follistatin, Shh; secreted by notochord
neural tube fusion
neural plate switches from E-cadherin expression to N-cadherin and N-CAM expression to prevent binding with ectoderm
D/V patterning of neural tube
BMP in dorsal and Shh in ventral –> create a gradient
What are mechanisms that control development?
cell signaling, morphogen gradient, TFs
What is a developmental program?
series of developmental events where each event leads in a controlled way to more events until the life cycle has come full circle
How does information processing occur?
transcription regulation and gene expression, signal transduction pathways, biochemical pathways, most cellular processes
Where is the information for development?
DNA sequence and epigenetic marks, cellular and extracellular structure, womb and environment
