#Question id: 7256
#Unit 5. Developmental Biology
Sox9 is an autosomal gene involved in several developmental processes, most notably bone formation. In the gonadal rudiments, Sox9 induces testis formation. Expression of the Sox9 gene is specifically upregulated by the combined expression of Sry and Sf1 proteins in Sertoli cell precursors. Thus, Sry may act merely as a “switch” operating during a very short time to activate Sox9, and the Sox9 protein may initiate the conserved evolutionary pathway to testis formation. Following statements are regarding to the functions of Sox9.
A. It appears to be able to activate its own promoter, thereby allowing it to be transcribed for long periods of time.
B. It activates the ability of β-catenin to induce ovary formation, either directly or indirectly.
C. It binds to cis-regulatory regions of numerous genes necessary for testis production.
D. Sox9 binds to the promoter site on the gene for anti-Müllerian hormone, providing a critical link in the pathway toward a male phenotype.
E. Sox9 inhibits the expression of the gene encoding Fgf9, a paracrine factor.
Which of the following statements are correct?
#Question id: 7257
#Unit 5. Developmental Biology
Following statements are regarding to the specification
of anterior-posterior axis in drosophila.
A. The oocyte moves into the posterior region
of the egg chamber, while nurse cells fill the anterior portion. The oocyte
nucleus moves toward the terminal follicle cells and synthesizes Gurken
protein.
B.
When Gurken binds to Torpedo, the terminal follicle cells differentiate into
posterior follicle cells and synthesize a molecule that activates protein
kinase A in the egg.
C.
Bicoid mRNA binds to dynein, a “plus-directed” motor protein associated with
the nongrowing end of microtubules; dynein moves the bicoid mRNA to the
anterior end of the egg.
D.
Oskar mRNA becomes complexed to kinesin I, a “minus-directed” motor protein
that moves it toward the growing end of the microtubules at the posterior
region, where Oskar protein can bind nanos mRNA.
Which of the following is incorrect?
#Question id: 7258
#Unit 5. Developmental Biology
A four-cell embryo normally develops into a blastocyst
consisting of trophectoderm (TE) cells on the outside and inner cell mass (ICM)
cells inside. The transplantation experiments were done with mouse embryos.
A. If a labeled cell is placed on the outside of a very early
embryo, it is likely to form extraembryonic tissues.
B. If a labeled cell is placed on the inside of a very early embryo, it is likely to form embryonic tissues.
According to above observations which of the following statement is true?
#Question id: 7259
#Unit 5. Developmental Biology
The mechanism that triggered to initiate limb bud formation involes:
A. making mesoderm instructive for limb formation
B. inducing epithelial-to-mesenchymal transitions
C. making mesoderm permissive for limb formation
D. inducing mesenchymal-to-epithelial transitions
E. specifying forelimb and hindlimb
Which of the following combinations are incorrect?
#Question id: 7260
#Unit 5. Developmental Biology
There are maternally-determined variations along the animal-vegetal axis that are necessary for normal development in sea urchin. Which of the following statements about regulation in sea urchin embryos is consistent with that fact?
#Question id: 7261
#Unit 5. Developmental Biology
The Turing model provides a framework for limb development. Following statements are regarding to this model:
A. In Turing’s model, morphogen A promotes the production of more morphogen A (autoactivation) as well as production of morphogen I. Morphogen I, however, inhibits the production of morphogen A (lateral inhibition).
B. In Turing’s model, morphogen A inhibits the production of more morphogen A (autoinhibition) as well as production of morphogen I. Morphogen I, however, promotes the production of morphogen A (lateral activation).
C. In Turing’s model, the reaction-diffusion dynamics can tell us how the limb bud acquires its proximal- distal polarity as well as how the number of digits is regulated at the distal tip of the limb.
D. The reaction-diffusion system has been proposed to be sufficient for establishing patterns of precartilage and noncartilage tissues.
E. According to this model, along the proximal-distal axis the AER dividing into two domains 1-the inhibitory domain 2-the active domain.
F. According to this model, along the proximal-distal axis the AER dividing into three domains 1-the inhibitory domain 2-the active domain 3-frozen domain.
Which of the following combinations are incorrect?