Question

The total nucleic acids are extracted from human cells and mixed with small beads that are attached to small oligonucleotides with the sequence 5'-TTTTTTTTTTTTTT-3'. After mixing, the beads are washed to remove unbound material. The analysis of the nucleic acids that have remained bound with the beads would demonstrate that they were composed of mostly:

a. DNA
b. tRNA
c. rRNA
d. mRNA
e. U1 RNA

Answer 1

The nucleic acids that remain bound to the oligonucleotide beads with a 5'-TTTTTTTTTTTTTT-3' sequence are mostly messenger RNA (mRNA), as mRNA has 3' poly(A) tails that can hybridize with the oligo(dT) sequence on the beads.

Step-by-step explanation:

The total nucleic acids extracted from human cells and mixed with oligonucleotides attached to beads with the sequence 5'-TTTTTTTTTTTTTT-3' would bind to nucleic acids with a poly(A) tail. The technique described takes advantage of the hydrogen bonding between the adenine (A) in RNA strands and the thymine (T) in the oligonucleotide sequence. Given that the beads are designed to hybridize with a poly(A) sequence, the nucleic acids that remain bound to the beads after washing would be composed of mostly messenger RNA (mRNA).

mRNA is known for having polyadenylated tails, generally referred to as poly(A) tails, at their 3' end. This poly(A) tail is recognized by the oligo-d(T) sequence on the beads. Since the question specifies that the bound nucleic acids would be composed mostly of a certain type, we can infer that it is mRNA, because other types of RNA such as ribosomal RNA (rRNA), transfer RNA (tRNA), U1 RNA, or DNA, do not typically have poly(A) tails.