The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On Earth, these primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of

#Question id: 4103

#XL - Q Biochemistry

In a biochemical experiment, you compare the products from splicing reactions carried out in vitro using three different substrates. In each case the substrate is a construct containing a single intron surrounded by two exons, and in all cases the construct is the same overall size. But in one case, the intron is a group I intron, in another a group II intron, and in the third an intron removed by the spliceosome. Each construct is labelled in a manner that allows it to be detected after gel electrophoresis, and each is tested in two reactions—one, conditions that support self-splicing, and two, in the presence of nuclear extract as well. Note that, for simplification, only the final products of the splicing reaction are seen, but before degradation of the introns.

 Which of the following observation is/are correct?

A. In lane A, the presence of nuclear abstract, a band for the lariat and the spliced product and pre-mRNA.

B. Lane B shows Group I Introns and Lane C is for Group II introns and reaction is nonself-splicing

C. Lane C is Group I intron. Splicing takes place in the absence and presence of nuclear abstract, and the reaction is self-splicing.

#Question id: 4126

#XL - T Zoology

Which one of the following is true about the genetic code?

#Question id: 4128

#XL - T Zoology

Which of the following statements about tRNA molecules is false?

#Question id: 4130

#XL - T Zoology

Which of the following is not true of tRNA molecules?

#Question id: 4131

#XL - T Zoology

Aminoacyl-tRNA synthetases (amino acid activating enzymes):

#Question id: 4132

#XL - T Zoology

In E. coli, aminoacyl-tRNA synthetases: