Many of the cell and tissue movements in Xenopus gastrulation happen simultaneously. Still identify the different types of behaviors that occur during Xenopus gastrulation:

A. Epiboly: The thinning and spreading of the animal cap cells over the vegetal hemisphere, powered by proliferation and radial intercalation.

B. Vegetal rotation: Vegetal cells asymmetrically press up against the inner blastocoel roof on the dorsal side.

C. Bottle cell formation and invagination: The leading edge of invaginating cells crawls up onto the blastocoel roof.

D. Involution and cell migration: Localized apical constriction at the dorsal blastopore lip creates anisotropic forces that foster invagination.

E. Convergence and extension: The targeted medial-to-lateral intercalation of cells on the midline (convergence) drives anterior-posterior axis elongation (extension).

Which of the following definition are correct according to their process?

#Question id: 4077

#Unit 3. Fundamental Processes

Which of the following is (are) associated with most polyadenylation events?

a. cleavage of the 5´ end of the RNA molecule

b. an assembly of a large, multiprotein complex

c. the AAUAAA site upstream of where polyadenylation will occur

d. a GU-rich or U-rich region near the cleavage site

e. slow addition of A residues followed by rapid addition of 200 to 250 more A residues

#Question id: 4078

#Unit 3. Fundamental Processes

Which of the following is (are) required for splicing to occur?

a. two transesterification reactions

b. intact, naturally occurring introns

c. formation of a lariat like structure

d. a branch-point G residue

#Question id: 4079

#Unit 3. Fundamental Processes

What is the evidence that pre-mRNAs are not synthesized unless machinery for processing is properly positioned?

#Question id: 4080

#Unit 3. Fundamental Processes

How the location of exons and introns within a gene are determined?

#Question id: 4081

#Unit 3. Fundamental Processes

Which of the following regulatory scenarios of cell-type-specific expression of fibronectin isoforms in humans is (are) consistent with information on known splicing factors?

a. A Tra-like splicing factor expressed in fibroblasts is required for inclusion of EIIIA and EIIIB exons.

b. An Sxl-like splicing factor is required in hepatocytes for exclusion of EIIIA and EIIIB exons.

c. A Tra-2-like factor enhances binding of the cleavage/polyadenylation complex in fibroblasts.

d. A Dsx-like protein is required to inhibit transcription of the fibronectin gene.

#Question id: 4082

#Unit 3. Fundamental Processes

Which of the following is (are) not involved in alternative splicing in eukaryotes?