Question

Total nucleic acids are extracted from a cultire of yeast cells and then are mixed with beads. 5'-TTTTTTTTTTTTTTTTTTTTTTTTTTT-3'

When you analyze the cellular nucleic acids that have stuck to the beads, which of the following is most abundant?
a)DNA
b)mRNA
c)tRNA
d)rRNA

Answer 1

The nucleic acid most abundant when mixed with beads bearing an oligo-d(T) sequence is mRNA, due to its poly(A) tail that allows it to bind to these beads while other nucleic acids like rRNA, tRNA, and DNA do not have this tail.

Step-by-step explanation:

When analyzing the cellular nucleic acids that have stuck to the beads with the sequence 5'-TTTTTTTTTTTTTTTTTTTTTTTTTTT-3', which represents an oligo-d(T) sequence used to bind to the poly(A) tails, the most abundant form of nucleic acid would be mRNA. This is because eukaryotic mRNA molecules have polyadenylated (poly(A)) tails at their 3' end that will bind to the complementary thymine-rich (oligo-d(T)) beads. Among the nucleic acid options given (DNA, mRNA, tRNA, and rRNA), mRNA is unique in having the poly(A) tail. While rRNA and tRNA are found in larger quantities within the cell, they do not have poly(A) tails and will not be isolated with this method. DNA, although plentiful, does not have a poly(A) tail and thus will not bind to oligo-d(T) beads.