The correct answer is B. The two DNA strands complement each other, with A base-paired with T and G base-paired with C. This means that A on the first strand is paired with T on the second strand, G on the first strand is paired with C on the second strand, and so on. Choice B correctly indicates the correct numbers of each base. It is important to note that A = T and G = C in the correct answer.

The correct order in which the enzymes participate in prokaryotic replication is as follows: F, E, C, D, B, A. Primase creates the RNA primer, polymerase III extends the primer with DNA and also proofreads it, polymerase I removes the primer using its 5′→3′ exonuclease activity, fills in the gap with its 5′→3′ polymerase activity, and removes errors using its 3′→5′ exonuclease activity. Finally, ligase creates the 5′→3′-phosphodiester bond that links the DNA synthesized by polymerases I and III.

Dideoxynucleotides lack a 3′-hydroxyl group, which prevents the formation of the 3′-hydroxyl → 5′phosphate bond that links nucleotides together in DNA. Therefore, the incorporation of a dideoxynucleotide into DNA would stop replication.

The genetic blueprint of an organism is contained in the sequence of deoxyribonucleotides in its DNA. However, it is through ribonucleic acid (RNA) that the genetic information is expressed. Transcription is the process by which a DNA strand serves as a template for RNA synthesis. Transcription produces messenger RNA (mRNA) that is translated into proteins, as well as other types of RNA molecules that perform various functions. These include ribosomal RNA (rRNA), transfer RNA (tRNA), and noncoding RNA (ncRNA). Transcription is highly selective, and signals in the DNA sequence instruct the RNA polymerase where and how often to start and stop transcription. Regulatory proteins also play a role in this process. The selectivity of transcription contributes to the biochemical differentiation of an organism's tissues. Additionally, RNA transcripts can undergo modifications that convert them into functional molecules. The complete set of RNA transcripts expressed by a genome is referred to as the transcriptome.

RNA structure is another important aspect to consider.
Correct answer = B. The two DNA strands are complementary to each other, with A base-paired with T and G base-paired with C. So, for example, the 20 A on the first strand would be paired with 20 T on the second strand, the 25 G on the first strand would be paired with 25 C on the second strand, and so forth. When these are all added together, the correct numbers of each base are indicated in choice B. Notice that, in the correct answer, A = T and G = C.
0.4. List the order in which the following enzymes participate in prokaryotic replication.
A. Ligase
B. Polymerase I (3′→5′ exonuclease activity)
C. Polymerase I (5′→3′ exonuclease activity)
D. Polymerase I (5′→3′ polymerase activity)
E. Polymerase III
F. Primase
Correct answer: F, E, C, D, B, A. Primase makes the RNA primer; polymerase (pol) III extends the primer with DNA (and proofreads); pol I removes the primer with its 5′→3′ exonuclease activity, fills in the gap with its 5′→3′ polymerase activity, and removes errors with its 3′→5′ exonuclease activity; and ligase makes the 5′→3′-phosphodiester bond that links the DNA made by pols I and III.
0.5. Dideoxynucleotides lack a 3′-hydroxyl group. Why would incorporation of a dideoxynucleotide into DNA stop replication?
The lack of the 3′-OH group prevents formation of the 3′-hydroxyl → 5′phosphate bond that links one nucleotide to the next in DNA.
RNA Structure, Synthesis, and Processing 31
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I. OVERVIEW
The genetic master plan of an organism is contained in the sequence of deoxyribonucleotides in its DNA. However, it is through ribonucleic acid (RNA), the “working copies” of DNA, that the master plan is expressed (Fig. 31.1). The copying process, during which a DNA strand serves as a template for the synthesis of RNA, is called transcription. Transcription produces messenger RNA (mRNA), which are translated into sequences of amino acids (proteins), and ribosomal RNA (rRNA), transfer RNA (tRNA), and additional RNA molecules that perform specialized structural, catalytic, and regulatory functions and are not translated. That is, they are noncoding RNA (ncRNA). Therefore, the final product of gene expression can be RNA or protein, depending upon the gene. [Note: Only ~2% of the genome encodes proteins.] A central feature of transcription is that it is highly selective. For example, many transcripts are made of some regions of the DNA. In other regions, few or no transcripts are made. This selectivity is due, at least in part, to signals embedded in the nucleotide sequence of the DNA. These signals instruct the RNA polymerase where to start, how often to start, and where to stop transcription. Several regulatory proteins are also involved in this selection process. The biochemical differentiation of an organism’s tissues is ultimately a result of the selectivity of the transcription process. [Note: This selectivity of transcription is in contrast to the “all-or-none” nature of genomic replication.] Another important feature of transcription is that many RNA transcripts that initially are faithful copies of one of the two DNA strands may undergo various modifications, such as terminal additions, base modifications, trimming, and internal segment removal, which convert the inactive primary transcript into a functional molecule. The transcriptome is the complete set of RNA transcripts expressed by a genome.
II. RNA STRUCTURE