Ramachandran plots can help increase the accuracy of models derived from x-ray crystallography data. The plot below was created by measuring phi, and psi for each amino acid residue in a 2.2 A resolution crystal structure. In the plot, which excludes Gly and Pro residues, selected residues (dots) are numbered 1 through 5.

Which of the following statements can be correctly stated for this plot in reference to selected residues?

A. Residues 1 and 3 are in either B sheets

B. residue 2 is in a right-handed a helix, and residue 4 is in a left-handed a helix.

C. If residue 5 were Gly, it might be in an acceptable position in the plot

#Question id: 7227

#Unit 5. Developmental Biology

The regulative ability of the limb bud has recently been highlighted by a remarkable experiment of nature. In numerous ponds in the United States, multilegged frogs and salamanders have been found. The presence of these extra appendages has been linked to the infestation of the larval abdomen by parasitic trematode worms. The eggs of these worms apparently split the developing tadpole limb buds in several places, and the limb bud fragments develop as multiple limbs. This shows:

A. The limb field represents a harmonious equipotent system. 

B. The limb field do not represents harmonious equipotential system because different types of genes express during proximal to distal growth.

C. The limb field represents coupled system wherein one gene maintain the expression of other genes.

D. The limb field represents a harmonious equipotent system because only Hox genes expresses all along the limb axis.

E. The limb field represents cells of the limb region can be instructed to form any part of the limb. 

Which of the following statements are correct?

#Question id: 7228

#Unit 5. Developmental Biology

Why do Drosophila wings develop in only one particular thoracic segment, legs in all three, and antennae on the head? Which of the following answer is correct?

#Question id: 7229

#Unit 5. Developmental Biology

Two embryos were injected with bicoid at early cleavage stage. What would be the phenotypes of the resulting embryos?

#Question id: 7230

#Unit 5. Developmental Biology

Following statements are being made regarding gradients of specific translational inhibitors in drosophila.

A. In the anterior region, Bicoid protein prevents translation of the caudal message by binds to a specific region of caudal’s 3′UTR. Here, bicoid recruits Bin3 (a translation inhibitor) which prevents translation of caudal in the anterior of the embryo.

B. In the posterior region, Nanos protein prevents translation of the hunchback message by forming a complex with several other ubiquitous proteins, including Pumilio and Brat. This complex binds to the 3’UTR of the hunchback message, where it recruits d4EHP and prevents the hunchback message from attaching to ribosomes.

C. In the anterior region, Bicoid protein prevents translation of the caudal message by binds to a specific region of caudal’s 5′UTR. Here, bicoid recruits pumilio and brat (a translation inhibitor) which prevents translation of caudal in the anterior of the embryo.

D. In the posterior region, Nanos protein prevents translation of the hunchback message by forming a complex with several other ubiquitous proteins, including bin3 and smaug. This complex binds to the 3’UTR of the hunchback message, where it recruits d4EHP and prevents the hunchback message from attaching to ribosomes.

Which of the following combination are incorrect?

#Question id: 7231

#Unit 5. Developmental Biology

Kragl and colleagues (2009) performed an experiment in which they transplanted limb tissue from a salamander whose cells expressed green fluorescent protein (GFP) into different regions of limbs of normal salamanders that did not have the GFP transgene. If they transplanted the GFP-expressing limb cartilage into a salamander limb that did not contain the GFP transgene, the GFP-expressing cartilage would integrate normally into the limb skeleton. They later amputated the limb through the region containing GFP-marked cartilage cells. The blastema was found to contain GFP-expressing cells, and when the blastema differentiated, the only GFP-expressing cells found were in the limb cartilage. Similarly, GFP-marked muscle cells gave rise only to muscle, and GFP-marked epidermal cells only produced the epidermis of the regenerated limb. Which of the following phenomenon is proved according to experiment?

#Question id: 7232

#Unit 5. Developmental Biology

During early development in sea urchin following events occur.

A. localized maternal factors in egg

B. organizer specified in vegetal region (micromeres)

C. induction of endomesoderm

D. b-catenin accumulation

E. animal–vegetal axis

which of the following sequence of developmental event is correct?