Development Flashcards
How did John Gurdon show that genetic infomation was retained in differentiated cell?
Transplant tadpole epitheal cell into empty frog egg
- Develops into a tadpole (the infomation has not been lost - but gene expression)
How is cell differentiation determined?
Intrinisic and extrinsic mechanism
Evidence for cytoplasmic factors?
Human liver cell and rat muscle cell fusion: production of human and rat muscle proteins
MyoD was found to be the factor + others that work in a positive feedback loop to ensure the correct structure is formed
What is the mothers role in development?
Sets up the cytoplasm of the egg to contain infomation needed before the mid-blastula transition (when the zygote takes over)
- Often involves setting up polarity
How may egg polarity be set up?
Local mRNA translation: drosophila using the cytoskelton to move the mRNA around the cell
Local mRNA: xenopus cortial cytoplasm rotation upon fusion with the sperm sets the dorsal-ventral axis
Environmental cues: Seaweed. Calcium pumps to determine apical-basal axis.
How is the fine-detailed map set up? how can this be investigated?
The zygotic genes
- Drosophila genetic screenings for mutants can be used to identify the genes responsible
Induction
- Xenopus: when animal cells come into contact with vegetal cells, the mesoderm is formed
What were the three groups of genes found from drosophila genetic screening?
GAP genes
Pair-rule genes
Segment polarity genes
Patten formation in chick limb? (proximal to distal and antero-posterior)
Time spent in the progress zone determines the proximal-distal development
Zone of polarising activity (ZPA) releases sonic hedgehog and cells measure their distance along tyhe antero-posterior axis by the concentration of sonic hedgehog
What is a homeotic mutation?
Muatation in a homeotic gene that cleanly transforms one body part to another area
Features of hox genes
Clustered
Co-linear
Highly conserved
Encode transcription factors with a homeodomain
