Following statements are regarding to gastrulation in chick embryo.

A. During gastrulation, future mesodermal and endodermal cells migrate from the epiblast through the primitive streak into the interior of the blastoderm.

B. An aggregation of cells, known as Hensen’s node, forms at the posterior end of the streak.

C. As the streak extends, cells of the epiblast move toward the primitive streak, through it, and then outward again underneath the surface to give rise internally to the mesoderm and endoderm, the latter displacing a lower layer of cells called the endoblast.

D. Cells that remain in the epiblast form the endoderm.

Which of the following statements are correct?

#Question id: 4233

#Unit 3. Fundamental Processes

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is __.

#Question id: 4234

#Unit 3. Fundamental Processes

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the __.

#Question id: 4235

#Unit 3. Fundamental Processes

What would be the consequence of a mutation in a bacterial cell that produces a defective aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNAs with the anticodon AAA?

#Question id: 4236

#Unit 3. Fundamental Processes

In bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. Which of the following statements explains this fact?

#Question id: 4237

#Unit 3. Fundamental Processes

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5′-CCGACG- 3′ (mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3′ to 5′ direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. Which of the following dipeptides will form from this mRNA?

#Question id: 4238

#Unit 3. Fundamental Processes

Use the following information to answer the question. A part of an mRNA molecule with the following sequence is being read by a ribosome: 5′-CCGACG- 3′ (mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3′ to 5′ direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form.