Coding 10 Flashcards
What happens to the energids in a syncitial drosophila embryo?
The nuclei and the energids migrate to the periphery and use ingression to make the syncitial blastoderm
What is an energid?
The cytoplasmic space that the nuclei in a syncitial blastoderm interact with
What do the pole cells form?
The posterior and the germ cell precursors
Relative to nuclear division when can cleavage occur?
When there are the right number of nuclei to form the syncitium
What is superficial cleavage?
When the yolk limits the cleavage of the embryo to the rim of the egg
What is a syncitial blastoderm?
A blastoderm is an embryo that has undergone cleavage and has a cavity and in this case the only membrane is the one surrounding the egg
What is the cellular blastoderm?
When the cell membranes fold inward between the nuclei and divide into individual cells
What are the maternal affect genes?
These are the genes that are needed for early embryonic development
What is the mid-blastula transition?
When the maternal mRNA are degraded the gap stages are added and the synchonicity of the cell division is lost
When do zygotes produce their own genes?
Cycle 11
When does zygote transcription get enhanced?
Cycle 14
How does the ventral tube form?
when the ventral midline folds inwards and then the ventral furrow forms which then pinches into the tube (analogous to the neural tube forming)
How does the germ band for?
When the cells converge at the ventral midline to form the embyo’s trunk
How do germ line cells form?
An oogonium generates an oocyte which divides and gives rise to 16 cells
What do germ line cells do?
They activate nurse cells
What do nurse cells do?
They make proteins and mRNA which are then transported into the oocyte
When are zygotic genes activated? (Before Vs. After)
After fertilization
What are gap genes?
Encodes for transcription factor that divides the embryo into 3 segments
What are pair-rule genes?
Divides the embryo into 7 segments and it is regulated by various gap gene products
What are segment polarity genes?
Transcription factors from pair-rule genes activate these genes to make 14 segments
How are bicoid and nanos tethered to the anterior or posterior?
By the 3’UTR to the unfertilized egg
When are bicoid and nanos translated?
After ovulation and fertilization
Since there is no cell membrane in a syncitial blastoderm what happens?
Polarity is established
What is the role of the nurse cells in relation to other genes?
It produces transcription factors that are used to regulate the expression of hunchback and caudal
How does bicoid repress caudal?
Bicoid proteins bind to the 3’UTR of the caudal and prevent the addition of the 5’ Cap which prevents caudal to be translated
Why does bicoid repress caudal?
If both are expressed the head and the thorax fail to synthesize proper regions in the anterior
How does nanos repress hunchback?
The nanos proteins bind to the 3’UTR of the hunchback mRNA and prevent the addition of the 5’Cap
What is bicoid?
A gene responsible for making the head in the anterior of the fly
What is nanos?
A gene responsible for making the tail in the posterior of the fly
What is caudal?
It activates genes responsible for making the hindgut
How is bicoid related to hunchback?
It upregulates and activates it
What impact drosophila cell fate?
Protein gradients and signals from other cells
What is the effect of gap mutants?
Lack large regions of the body
What is the effect of pair rule mutatations?
Lacks every other segment