Select all that applies. What happens during the mid-blastula transition in Drosophila development? I. Cleavages become asynchronous II. New mRNA is made III. Transfer from maternal to zygotic control of development occurs

I, II, and III

What initiates gastrulation in Drosophila?

Formation of a ventral furrow

What is the importance of temporal order in Drosophila development?

It regulates the sequential transcription of different genes

These morphogens' gradients determine the specification of different cell types.

Bicoid and dorsal

Select all that applies. How is dorsal-ventral polarity regulated in Drosophila? I. By the movement of the nucleus to the dorsal-anterior of the oocyte II. By the formation of a gradient of Dorsal protein III. By the synthesis of proteins in the dorsal side of the egg

I, II, III

What is the role of Dorsal protein in Drosophila development?

Establishing dorsal-ventral polarity

How does Dorsal protein form a gradient in the Drosophila embryo?

Through its movement into various nuclei

Which cells incorporate the most Dorsal protein and become mesoderm in Drosophila?

Ventral surface nuclei

What initiates the anterior-posterior polarity in Drosophila development?

Maternal effect genes

How do morphogens affect gene expression in Drosophila?

By establishing concentration gradients within the embryo

Which proteins activate the genes responsible for the anterior portions of the fly?

Bicoid and Hunchback

Which protein activate the genes responsible for the posterior portions of the fly?

Caudal

The unsegmented anterior and posterior extremities are regulated by the activation of this protein at the anterior and posterior poles of the egg.

Torso

How do the gap genes influence the expression of the pair-rule genes?

By activating and repressing the pair-rule genes

Where are the homeotic selector genes located in Drosophila?

Hom-C gene complex on chromosome III

Where do organs form in Drosophila embryonic development?

Intersection of dorsal-ventral and anterior-posterior regions

What defines the boundaries of transcription for the pair-rule genes?

Gap gene proteins

13. How many bands of transcription do the pair-rule genes form along the anterior-posterior axis?

Seven

Along the anterior-posterior axis, each band of transcription of the pair-rule genes corresponds to how many parasegments?

Two

The pair-rule genes have modular enhancers that result in their activation in:

Specific patterns or stripes

What is the role of the homeotic selector genes in Drosophila development?

To specify the individual segments and determine segment identities

What type of cleavage occurs in amphibians?

Holoblastic cleavage

What initiates amphibian gastrulation?

Invagination of the bottle cells

What are the driving forces behind ectodermal epiboly and convergent extension in amphibian gastrulation?

Intercalation events and merging of tissue layers

What is the critical role of fibronectin in amphibian gastrulation?

Enabling mesodermal cell migration into the embryo

Which proteins are secreted by the organizer to block the BMP signal and ventralize the mesoderm in amphibian development?

Noggin, Chordin, and Follistatin

Dorsal-ventral specification in amphibians begins with:

Maternal messages and proteins stored in the vegetal cytoplasm

The Nieuwkoop center is formed by the translocation of which proteins to the dorsal side of the egg?

Disheveled and Wnt11

How is the Nieuwkoop center formed?

Accumulation of β-catenin on the dorsal side of the embryo

What is the function of the β-catenin and Tcf3 transcription factor complex in amphibian development?

Activating the siamois and twin genes on the dorsal side of the embryo