Which model most accurately describes how maternal-effect genes regulate embryon

Question

Which model most accurately describes how maternal-effect genes regulate embryonic development in Drosophila?

1 Embryonic development is initiated by maternal effect gene products confined to the anterior end of embryo. These gene products set off a cascade of activation of zygotic genes starting at the anterior end moving toward the posterior end.

2. Embryonic development is initiated by maternal effect gene products confined to the posterior end of embryo. These gene products set off a cascade of activation of zygotic genes starting at the posterior end moving toward the anterior end.

3. Embryonic development is initiated by molecular gradients of maternal effect gene products throughout the embryo. These gene products activate or repress the expression of zygotic genes in both a temporal and spatial manner.

4. Embryonic development is initiated by maternal effect genes that activate zygotic genes within the anterior end of the embryo and repress zygotic genes within the posterior end of the embryo.

Explanation / Answer

The answer is

3. Embryonic development is initiated by molecular gradients of maternal effect gene products throughout the embryo. These gene products activate or repress the expression of zygotic genes in both a temporal and spatial manner.

The maternal-effect genes encode for proteins that establish a concentration gradient across an embryo. Transcripts, or mRNAs, from many of these maternal-effect genes, can be found in the unfertilized eggs of females. This is why they are known as the maternal-effect genes, as they are specified by the genotype of the mommy fly.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.