A coding sequence is the sequence of DNA that will code for a particular protein. In this process an messenger or mRNA molecule is transcribed from DNA and later translated into a protein by ribosomes. Messenger or mRNA is flanked by an upstream 5’ UTR untranslated leader sequence and a downstream 3’ UTR untranslated region that follows the termination codon of the synthesized protein.

The term “directionality” refers to the chemical orientation of a molecule. In DNA and RNA, directionality is described as 3’ (three prime) or 5’ (five prime). 3’ refers to the third carbon group in a sugar ring, which terminates in a hydroxyl group, and 5’ refers to the fifth carbon in the sugar ring. In transcription, RNA polymerase reads the template DNA strand in a 3’ to 5’ direction. Reading the template DNA strand in this direction allows transcription to proceed without primers and Okazaki fragments. This yields an RNA molecule that is formed in a mirrored 5’ to 3’ direction.

Termination is the final stage of transcription. During this stage, RNA polymerase reaches a terminator signal in the template DNA strand. This triggers the release of the transcriptional complex and the cleavage or release of the RNA transcript. Post cleavage, a sequence of adenines is added to the 3’ end of the new transcript through a process called polyadenylation. The resulting poly-A tail is important in translation, stability, and export of the transcript.

Promoter sequences are regions of DNA located upstream of transcription start sites. Transcription factors bind to the promoter sequence, which promotes the binding of RNA polymerase and initiation of transcription. Together, along with activators and repressors, these make up the pre-initiation complex. A well-characterized promoter sequence is called the TATA box, which is present within promoters of  of human genes.

The only correct post-transcriptional modification from the answer choices is the addition of a 5' (methyl guanosine) cap. The remaining answer choices are either false, or examples of post-translational modifications.

RNA polymerase transcribes a DNA template in the 3' to 5' direction, creating an RNA molecule 5' to 3'. The DNA sequence given in the question therefore needs to be flipped around and read in the 3' to 5' direction in order to determine the resulting what the RNA sequence will be 5' to 3'. Additionally, the nitrogenous base thymine (T) is replaced by uracil (U) in RNA, so every location where a T would go in the RNA sequence needs to be replaced by a U.

From the passage, chromosome 6 carries the information for the MHC molecules. The chromosomes are stored in the nucleus of the cell. Therefore, transcription occurs in the nucleus. 

The process by which the genetic code of DNA is copied into a strand of messenger RNA is called transcription. Translation uses messenger RNA, transfer RNA, and ribosomal RNA to create a chain of amino acids that become a protein. Replication is the reproduction of two strands of DNA that are used in a new cell.

When finding the mRNA transcript from a template, there are two things to keep in mind:

1. The template strand will be complementary to the transcript, so it will be read in the opposite direction

2. Since the template strand is made from DNA, it will have thymine bases instead of uracil (which is found in RNA in place of thymine).

First, we can reverse the direction of our given DNA sequence.

5'-TACGCATT-3'

3'-TTACGCAT-5'

Then, complete each base pair. Guanine (G) and cytosine (C) always pair, and adenine (A) and thymine (T) always pair. In this case, since we are dealing with RNA, uracil (U) will have an adenine complement.

5'-AAUGCGUA-3'