Gene expression is the showing (or hiding) of a specific trait. The lac operon controls whether or not it produces the enzyme B-gal to digest lactose. The lac operon has a repressor protein on the operator to block the enzyme from being produced. This makes sure the operon isn’t producing unnecessary B-gal. In the presence of lactose, the repressor protein temporarily leaves the operon and the RNA polymerase begins to produce the B-gal enzyme. The first picture shows the operon. The second picture shows the operon turned off. The third picture shows the operon turned on.

This is our original DNA molecule we built. Each side has four nucleotides, a sugar (deoxyribose), and a phosphate group.

In order for a cell to make proteins, the DNA- or more specifically, the part of DNA that has the plan to make proteins- needs to somehow be transferred to the ribosome of a cell. DNA however, cannot leave the nucleus. So, a certain type of messenger RNA called RNA polymerase enters the nucleus, and separates the part of DNA with the protein plan, as shown above.

   Finally, the RNA polymerase adds complementary RNA nucleotides to the side of the DNA with the protein plan. Once this is completed, the complementary RNA nucleotide strand is transported back to the ribosome in order to make proteins. The DNA closes back up again, and all proceeds as normal.

This video is depicting the four phases of mitosis. The first phase that occurs is prophase, which is the condensing of chromatin into chromatids which bond to a common centromere, and the nuclear membrane starts to break down. The mitotic spindle begins to form as well. The second phase that occurs is metaphase, where the sister chromatids line up across the midpoint of the cell. The third phase to occur is anaphase, where the sister chromatids splt at the centromere, and pull to opposite poles of the cell. The final phase of mitosis is telophase, where two new nuclear membranes form, and the cell splits.