11/ drosophila as developmental and genetic models Flashcards
1
Q
what is a centi morgan
A
- a measure of distance
- between genes w a 1% chance of recombination
2
Q
micropyle
A
sperm entry point into egg
2
Q
forward genetics
A
- we have phenotype and want to find gene
- positional identification/cloning
2
Q
how do embryos start to develop
A
- as a syncytium - united cell w multiple nuclei
- at 3 hours post fertilisation embryo consists of single layer of cells enclosing the yolk
- at posterior of embryo the pole cells are separated off - these will form germ line
2
Q
reverse genetics
A
- we know gene and want to find phenotype
- gene knockout
3
Q
drosophila life cycle
A
- fertilised cleavage, syncytial blastoderm, gastrulation forms embryo,
- hatching at 24h
- lava undergoes malting to form 3 successive instars
- pupa then metamorphosis into adult fly
- sexual maturity 9 days after being laid
3
Q
what did mutant saturation screening lead to
A
- basic understanding of how genes are controlling elaboration of a body plan
- molecular identification of many new genes and cell to cell signalling pathways
- confirmed genetics a powerful tool to dissect biological processes
3
Q
what is saturation screening
A
- mutation chemical - EMS- used to randomly mutate genes
- average gene destroyed with a chance of 1/500
- mutated genes need to be homologous to show their phenotype
4
Q
gastrulation
A
ventral furrow, germ band extension, segmentation
4
Q
ovary - how do eggs develop
A
- strings with dividing stem cells at the tip
- these break off and mature into egg cells to be laid
4
Q
what are denticles
A
- anti slip structures to allow the larva to crawl over food
- each segment has a characteristic denticle pattern
- denticles have particular orientation which allows you to recognise a/p polarity in each segment
5
Q
Pair rule gene mutation
A
- every other segment is missing
- pair rule gene required for forming every other segment
5
Q
amnioserosa
A
- one cell thick epithelial tissue that covers dorsal side of embryo
- involved in dorsal closure, germ band extension and germ band retraction
5
Q
gap gene mutation
A
- T1 segment is fused to A1, T2 and T3 missing
- gap gene required for setting up T2 and T3
5
Q
what are imaginal disks
A
groups of cells in larva that form mouthparts, antenna, eye, leg, haltere, wing and genitalia
