Question

cDNA libraries are constructed by using reverse transcriptase to synthesize DNA from mRNA that has been isolated from a cell. Since cDNA libraries represent mRNA sequences found within a cell, which of the following would be missing from a gene's sequence in a eukaryotic cDNA library? A) a start codon B) exons C) a signal sequence for polyadenylation D) introns E) a stop codon

Answer 1

1. D) introns

If cDNA library is the sequence of mRNA sequence so if DNA is reverse transcripted then the DNA may lack the introns which are spliced inorder to get an active protein during the translation process.

1. D)chemical 4

In Ames test if the number of colonies is huge in chemical+ liver enzymes petri dish than the control dish then the chemical is said to be mutagenic.

Even chemical 1 and chemical 2 have a increased number of colonies compared with control group but it is not much compared with chemical 4 and this can be due to point mutation.