From the lab result, transcription and translation had just occurred in order to create the MHC molecules. In order for transcription and translation to occur, the DNA must not have been condensed (euchromatic).

Euchromatin is a term used to describe an area within the DNA that is much less condensed and highly active transcriptionally. Typically, these areas are seen in highly active cells that are producing many proteins. On the contrary, Heterochromatin are areas that are much more condensed and much less transcriptionally active. On electron micrograph images, euchromatin areas are typically lighter stained vs heterochromatin areas are much more densely stained.

Replication is the process in which the DNA molecule produces two new complementary strands. Transcription produces a messenger RNA, and translation produces a chain of amino acids that become a protein.

DNA polymerase is the primary enzyme involved in DNA replication. It is responsible for adding nucleotides to the growing DNA chain in the 5' to 3' direction. This enzyme also has proofreading functionality, which allows it to remove nucleotides that are mispaired in the 3' to 5' direction and replace them with the correct nucleotide.

The correct answer must complementary base pair with the fragment in the 3’ to 5’ direction because the strands run anti-parallel to each other. Only three of the given options that will run anti-parallel, but only one complements the DNA properly.

The correct answer is Helicase because it is involved with the separation of the two strands of DNA by breaking the hydrogen bonds between them. Primase lays down the RNA primer so that the polymerase enzymes can attach and start adding complementary base pairs. SSBs are single stranded binding proteins which anchor the separated strands and keep them from annealing to each other.

The primary function of the ribosomes bound to the rough endoplasmic reticulum is to synthesize proteins for transport to the cell exterior or extracellular matrix. These ribosomes produce polypeptides that are packaged into vesicles by the Golgi apparatus and transported to the membrane. The vesicle then fuses with the membrane, either releasing proteins out of the cell or incorporating them into the cell membrane.

Nuclear ribosomes synthesize replication and transcription proteins into the nucleus, while cytoplasmic ribosomes produce cytoplasmic proteins.

During DNA replication, helicase is responsible for unwinding the DNA helix and topoisomerase cleaves portions of the sugar-phosphate backbone to release tension in the strands. DNA polymerase then enters the replication bubble created by helicase. The bubble has two sides, each with a leading strand and a lagging strand. The leading strand at one side of the bubble is the lagging strand at the other, since DNA is anti-parallel. DNA polymerase can only synthesize in the 5'-to-3' direction; the strand oriented in the 3'-to-5' direction at the replication fork is known as the lagging strand since it must be replicated in pieces in the reverse direction. These pieces are known as Okazaki fragments.

DNA ligase is the protein responsible for fusing breaks in the sugar-phosphate backbone. It repairs the bonds broken by topoisomerase and creates phosphodiester bonds between Okazaki fragments.

Heterochromatin is “dark” chromatin that represents DNA that is not active in transcription. The fact that it is “dark” implies that it is condensed and inaccessible by polymerases. Heterochromatin is created when DNA is tightly wound around histones. This tight winding prevents transcription proteins from interacting with the DNA. Heterochromatin is most common in the nucleus during mitosis, when no transcription is taking place. In contrast, euchromatin is capable of being transcribed and is most common during interphase, when most cellular growth and production occurs.

Translation occurs outside of the nucleus and uses mRNA as a template, not DNA.