Question

(03.05 MC) In which of the following ways is DNA replication different from DNA transcription? (2 points) New cells can only be created after transcription has taken place. Replication results in mRNA strands while transcription creates new DNA. Transcription happens outside the nucleus and replication happens inside the nucleus. Thymine is used in replication while uracil is used in transcription.

Answer 1

The right answer is thymine is used in replication while uracil is used in transcription.

If DNA is the carrier of heredity by replicating itself, it is the RNA, ribonucleic acid, which is generally used in cells as an intermediate gene to make the proteins they need (thanks to the transcription). RNA is also involved in many chemical reactions in the cell.

DNA is a polymer of deoxyribonucleic bases, more commonly called nucleotides. Each nucleotide consists of a phosphate group (or phosphoric acid) bonded to a sugar, deoxyribose, itself linked to a nitrogenous base. These bases are four in number: adenine (denoted A), thymine (denoted T), cytosine (denoted C) and guanine (denoted G). The DNA backbone consists of the sugar-phosphate repeat (the presence of uracyl (U) in the DNA shows that it is damaged.

RNA is usually synthesized in cells from a DNA template of which it is a copy. There are four nucleic bases in RNA: adenine, guanine, cytosine and uracil.

The thymine of the DNA is replaced by an uracil in the RNA, and the substitution of deoxyribose by a ribose makes the RNA chemically less stable than the DNA.

Answer 2

We presented with several statements after the question. Only one of these statements are correct.

DNA replication is the process in which a single strand of DNA, acting as the parent strand, forms two new strands of DNA. DNA transcription is the process of copying the information of the DNA strand and delivering this information into a strand of mRNA. These processes may sound similar, but there are key differences. We must look at the building blocks of DNA and RNA. Both structures are composed of four different bases, however, only three of these bases are shared between structures and they each have a unique fourth base. In DNA, the fourth base is thymine and it is uracil in RNA. We already established that DNA replication forms new strands of DNA, which would use thymine by default. DNA transcription results in formation of mRNA which would therefore use uracil.

The correct statement from the choices provided is the following:

Thymine is used in replication while uracil is used in transcription.