Proofreading occurs during the elongation phase of transcription. RNA polymerase's movement over the DNA template strand includes a backtracking motion that allows RNA polymerase to proofread the newly synthesized RNA transcript.

Telomeres and centromeres are composed of heterochromatin. In contrast to euchromatin, heterochromatin's genes are generally in an inactive state. This is because the genetic material is highly condensed. Often, heterochromatin is thought of as "junk DNA". Since telomeres are slowly being degraded during DNA replication, the cell does not want to have active or important genes in this area. Same goes for centromeres, where there is the possibility of chromatids not separating evenly across the centromere in anaphase.

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'

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.

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.

Proteins are coded for by RNA, which is coded for by DNA. The central dogma of molecular biology is the general sequence for the flow of information in coding for a protein. An mRNA strand is created using the DNA strand as a template. This new strand of mRNA then leaves the nucleus and is used as a template for 3-pronged tRNA molecules carrying amino acids to create a chain, which will eventually create a protein.

The central dogma of molecular biology is the general sequence of DNA to RNA to protein.

Following DNA transcription, the resulting RNA molecule must be modified before leaving the nucleus. Proteins in the nucleus add a 5' cap to the 5' end of the RNA strand, and a poly-A tail to the 3' end. These additions help prevent degradation of the transcript by any hydrolytic enzymes in the cytosol. Protein complexes called spliceosomes interact with the transcript to remove segments of non-coding RNA called introns. The remaining transcript following the excision of introns is composed only of coding segments of RNA, known as exons.

Though introns are removed during post-transcriptional modification, exons are not inserted. Rather, they are simply the remaining RNA sequences after the introns have been spliced out.

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.

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.

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.