Question

The total nucleic acids are extracted from a culture of yeast cells (remember these are eucaryotes) and are then mixed with resin beads to which the polynucleotide 5′-TTTTTTTTTTTTTTTTTTTTTTTTT-3′ has been covalently attached. After a short incubation, the beads are then extracted from the mixture. When you analyze the cellular nucleic acids that have stuck to the beads, which of the following will be most abundant?

A. DNA.
B. tRNA.
C. rRNA. (it is not this one, I put this and it was wrong.)
D. mRNA.
E. Primary transcript RNA.

Answer 1

The most abundant nucleic acids that stick to resin beads attached with oligo(dT) are mRNAs, due to their poly(A) tails which bind to the complementary sequence on the beads.

Step-by-step explanation:

When analyzing the cellular nucleic acids that have adhered to the resin beads with covalently attached polynucleotide sequence 5′-TTTTTTTTTTTTTTTTTTTTTTTTT-3′, the most abundant will be mRNA. This is because eukaryotic mRNA molecules have a poly(A) tail at their 3' end, which is complementary to the oligo(dT) sequence attached to the beads. This technique, known as oligo-d(T) chromatography, specifically isolates mRNAs that have a poly(A) tail, separating them from other types of RNA and DNA. tRNA, DNA, and rRNA will not adhere to the beads in significant amounts because they do not have the poly(A) tail. The primary transcript RNA, which does have a poly(A) tail, is included in the broader category of mRNA during isolation.