A) Germ cell specification in Drosophila occurs by maternally contributed determinants. In Drosophilla, germ cells can easily be identified very early in embryogenesis, when their differentiation as germ cells is assured by the localisation of maternally inherited determinants before, or immediately following, fertilisation. During oogenesis in Drosophila melanogaster, RNAs and proteins are synthesised by the nurse cells. These products are transported through cytoplasmic bridges to the oocyte where They become localised to the posterior of the ooplasm both by molecular anchoring at the posterior of the oocyte, and by posterior-specific translational and transcriptional regulation. This posterior ooplasm is the germ plasm, or germ line determinant. During early embryogenesis, cells which inherit the germ plasm become the primordial germ cells. One of the important gene that contributes to germ cell specification in Drosophila is Nanos. b) Neural crest cell specification is due to the cell signalling and depends on BMP signalling in the prospective epidermis and Wnt signalling from the underlying mesoderm. C) Anterior -posterior specification in Drosophila is initiated by maternal effect genes that produce messenger RNA that are placed in different regions of egg . These mRNA encode transcriptional and translational regulatory protiens that diffuse through the syncytial blastoderm and activates or repress the expression of certain zygotic genes. One important maternal effect gene in this respect is bicoid gene. Solution A) Germ cell specification in Drosophila occurs by maternally contributed determinants. In Drosophilla, germ cells can easily be identified very early in embryogenesis, when their differentiation as germ cells is assured by the localisation of maternally inherited determinants before, or immediately following, fertilisation. During oogenesis in Drosophila melanogaster, RNAs and proteins are synthesised by the nurse cells. These products are transported through cytoplasmic bridges to the oocyte where They become localised to the posterior of the ooplasm both by molecular anchoring at the posterior of the oocyte, and by posterior-specific translational and transcriptional regulation. This posterior ooplasm is the germ plasm, or germ line determinant. During early embryogenesis, cells which inherit the germ plasm become the primordial germ cells. One of the important gene that contributes to germ cell specification in Drosophila is Nanos. b) Neural crest cell specification is due to the cell signalling and depends on BMP signalling in the prospective epidermis and Wnt signalling from the underlying mesoderm. C) Anterior -posterior specification in Drosophila is initiated by maternal effect genes that produce messenger RNA that are placed in different regions of egg . These mRNA encode transcriptional and translational regulatory protiens that diffuse through the syncytial blastoderm and activates or repress the expression of certa.

1. A) Germ cell specification in Drosophila occurs by maternally contributed determinants. In
Drosophilla, germ cells can easily be identified very early in embryogenesis, when their
differentiation as germ cells is assured by the localisation of maternally inherited determinants
before, or immediately following, fertilisation.
During oogenesis in Drosophila melanogaster, RNAs and proteins are synthesised by the nurse
cells. These products are transported through cytoplasmic bridges to the oocyte where They
become localised to the posterior of the ooplasm both by molecular anchoring at the posterior of
the oocyte, and by posterior-specific translational and transcriptional regulation. This posterior
ooplasm is the germ plasm, or germ line determinant. During early embryogenesis, cells which
inherit the germ plasm become the primordial germ cells.
One of the important gene that contributes to germ cell specification in Drosophila is Nanos.
b) Neural crest cell specification is due to the cell signalling and depends on BMP signalling in
the prospective epidermis and Wnt signalling from the underlying mesoderm.
C) Anterior -posterior specification in Drosophila is initiated by maternal effect genes that
produce messenger RNA that are placed in different regions of egg . These mRNA encode
transcriptional and translational regulatory protiens that diffuse through the syncytial blastoderm
and activates or repress the expression of certain zygotic genes.
One important maternal effect gene in this respect is bicoid gene.
Solution
A) Germ cell specification in Drosophila occurs by maternally contributed determinants. In
Drosophilla, germ cells can easily be identified very early in embryogenesis, when their
differentiation as germ cells is assured by the localisation of maternally inherited determinants
before, or immediately following, fertilisation.
During oogenesis in Drosophila melanogaster, RNAs and proteins are synthesised by the nurse
cells. These products are transported through cytoplasmic bridges to the oocyte where They
become localised to the posterior of the ooplasm both by molecular anchoring at the posterior of
the oocyte, and by posterior-specific translational and transcriptional regulation. This posterior
ooplasm is the germ plasm, or germ line determinant. During early embryogenesis, cells which
inherit the germ plasm become the primordial germ cells.
One of the important gene that contributes to germ cell specification in Drosophila is Nanos.
b) Neural crest cell specification is due to the cell signalling and depends on BMP signalling in
the prospective epidermis and Wnt signalling from the underlying mesoderm.
C) Anterior -posterior specification in Drosophila is initiated by maternal effect genes that

2. produce messenger RNA that are placed in different regions of egg . These mRNA encode
transcriptional and translational regulatory protiens that diffuse through the syncytial blastoderm
and activates or repress the expression of certain zygotic genes.
One important maternal effect gene in this respect is bicoid gene.