14. Drosophila development Flashcards
Describe Drosophila development? (5)
1) fertilisation
2) embryonic development
3) hatching
4) pupation
5) metamorphosis
Why is drosophila a model organism for early development?
Segmentation of adult can be mapped to larval segments
Body plan determined by hierarchy of developmental
genes
What two types of genes regulate segmentation pattern in drosophila? (2)
1) Maternal effect genes
2) Zygotic genes
What do maternal effect genes do?
Phenotype of progeny is determined by maternal genotype
What do zygotic genes do?
Phenotype of individual is determined by the individual’s genotype
1) Segmentation Genes - regulate segments of fly
2) Homeotic Genes - determines structures (wings, legs, etc…)
What are the 4 functional classes of genes required for early development? (4)
- Egg-polarity genes
- Gap genes
- Pair-rule genes
- Segment polarity genes
Describe the nomcluture in maternal effect genes?
A gene symbol in UPPERCASE normal indicates a wild-type allele
A gene in lower case, is the mutant allele
Where is the anterior-posterior polarity determined?
The oocyte
what are the 2 most important maternal effect genes? (2)
BICOID
NANOS
Where are BICOID and NANOS located in oocyte?
BICOID mRNA located at anterior
NANOS mRNA located at posterior
When does translation of BICOID and NANOS happen?
After fertilisation (only)
How to BiICOID and NANOS produce opposing gradients in the early embryo?
By being tethered to they respective pole of the oocyte
What is the relative concentration of BICOID and NANOS important for?
Regulating the zygotic genes
What are the 3 categories of zygotic genes? (3)
GAP genes
Pair-rule genes
Segment Polarity genes
What do zygotic genes do?
specify more and more restricted domains of the embryo
What do homeotic genes do?
regulate the structures that develop on each segment of the adult fly
Why were homeotic genes identified?
Homeotic Genes were identified because thereis atransformationof organs in which the developmental fate of an organ is changed to that of another (replacement)
What are homeotic genes organised into?
Complexes
What kind of transcription factors are homeotic genes?
homeodomain transcription factors
What do homeodomain transcription factors do?
Regulate genes that specify tissue/organ primordia
Are all homeobox contain genes homeotic genes?
No
What are homeotic genes in humans and mice called?
Hox genes
How many Hox clusters are there in mice and humans?
4 (A,B,C,D)
What genes regulate human development?
Hox genes
Where do mutations take place to cause large deletions? (2)
Mutations in ME(maternal effect) or major zygotic genes cause large deletions
What do homeotic mutations result in?
Transformations
How are homeotic genes for development of drosophila structures such as legs or wings arranged?
These genes are arranged in 2 clusters, collectively called the
Hom-C cluster (antennapedia and biothorax)
