Topoisomerase I functions as a stress reliever during DNA replication. DNA coils and supercoils, and without topoisomerase, the tension caused by this winding would not be able to dissipate.  

The correct matches between prokaryotic DNA polymerase type and function are:

DNA polymerase I - fills in gaps in lagging strand

DNA polymerase II - DNA repair

DNA polymerase III - primary enzyme for DNA synthesis

Note: The functions of certain DNA polymerases in eukaryotes and prokaryotes are not the same.

Transcription is the second process involved in the production of proteins from a gene. The three processes are DNA replication, transcription, and translation. DNA replication involves replication of DNA from a parent strand, transcription involves the synthesis of a RNA molecule from a DNA molecule, and translation involves the conversion of the mRNA molecule to a polypeptide.

As mentioned, transcription produces an RNA molecule from a DNA molecule (parent strand). Recall that RNA molecules have uracil, whereas DNA molecules have thymine; therefore, the product will contain more uracil.

Amino acids are found in proteins. Since the products of transcription are nucleic acids (RNA molecules) they won’t contain any amino acids. Recall that a nucleic acid consists of pentose sugar molecules (ribose in RNA and deoxyribose in DNA), nitrogenous bases (adenine, guanine, cytosine, thymine (in DNA), and uracil (in RNA)), and phosphate groups.

RNA polymerase is an important enzyme involved in transcription. Its function is to add nucleotides to the growing mRNA chain. Although it adds complementary nucleotides to the DNA, RNA polymerase itself doesn’t bind to complementary DNA sequences, rather it binds at promoters.

There are three types of RNA molecules. First, mRNA molecules are the main products of transcription that undergo translation to produce most of the proteins found in a cell. Second, tRNA molecules are special RNA molecules that facilitate the addition of amino acids to a growing polypeptide chain during translation. Third, rRNA molecules are components of ribosomes and are synthesized in the nucleolus (location of assembly of ribosomes). The enzyme in this question is involved in the production of rRNA molecules. RNA polymerase I is used in production of rRNA molecules. RNA polymerase II is used for mRNA molecules and RNA polymerase III is used for tRNA molecules.

Prokaryotic and eukaryotic transcription are similar in many ways; however, they are also different from one another. One main difference is that in eukaryotic transcription there are several events that occur after the completion of transcription. These events are called post-transcriptional modifications.

There are three main post-transcriptional modifications: polyadenylation, capping, and splicing. Polyadenylation involves the addition of multiple adenine molecules at the 3’ end of the newly synthesized RNA molecule. This segment of RNA with multiple adenine molecules is called the poly A tail. Capping involves the addition of a methyl cap to the 5’ end of the RNA molecule. Splicing involves the excision of segments of the mRNA molecule that aren’t used in translation. These segments are called introns and the usable segments are called exons. The exons are ligated back together and the end product is released into the cytoplasm where it can undergo translation.

Products of prokaryotic transcription don’t undergo any of these post-transcriptional modifications and are immediately translated into proteins.

Transcription is the process of producing RNA molecules from a parent strand of DNA. The first step in transcription involves the binding of a sigma factor to inactive RNA polymerase, which in turn binds to the promoter region on the DNA molecule. After the binding of RNA polymerase to the DNA promoter, RNA polymerase gets activated and removes the hydrogen bonds between nucleotides of the double stranded DNA. Finally, RNA polymerase adds complementary nucleotides to the growing RNA molecule.

After completion of transcription, RNA molecules undergo post-transcriptional modifications and exit the nucleus and enter cytoplasm, where it can undergo translation.

RNA Polymerase II is used to catalyze the polymerization of mRNA during transcription. RNA polymerase I catalyzes the polymerization of rRNA, and RNA polymerase III catalyzes the polymerization of tRNA.

If the coding DNA reads 5’ AATGACGTC 3’, then the template strand would read 3’ UUACTGCAG 5’. The mRNA transcription would read 5’ AAUGACGUC 3’. The corresponding tRNA anti-codons would be 3’ UUA 5’ 3’ CUG 5’; 3’ CAG 5’, which produce the amino acids Asn-Asp-Val. To determine the amino acid sequence, you find the portion of the genetic code table corresponding to the DNA or mRNA, not the tRNA, nucleotides. (That's why ”Leu-Leu-Gln" is incorrect.)

The "central dogma" of biology says that information goes from DNA via transcription to RNA via translation to proteins. Reverse transcriptases, however, employed by retroviruses, synthesize DNA from RNA. As for the other enzymes: one function of helicases (among others) is to pull apart double helix strands. Catalase breaks down hydrogen peroxide. Carboxylase adds a carboxyl group to a substrate, and a ligase creates a bond between two molecules, for example, via a phosphodiester bond.

The spliceosome first releases the 5' exon by forming a lariat structure (2'-5' phosphodiester) bond between two introns in a transesterification reaction. Then, the exons are spliced together with another transesterifaction reaction, and the intron lariat is released.