Drug companies frequently market new versions of their drugs

Drug companies frequently market new versions of their drugs that contain a specific isomer of the drug they were previously selling. For example, the antidepressant citalopram was sold for many years, and was a mixture of two isomers of the drug. Later the same company released escitalopram, which contained only one of the two isomers. The economic advantages to the company are obvious. Explain the scientific basis of this decision to release a new version of an old drug. The major difference between prokaryotes and eukaryotes is that eukaryotes use membranes to form organelles within them seals, but prokaryotes do not. Eukaryotes package their DNA within the nucleus, a structure that prokaryotes do not have. List three advantages that eukaryotes have over prokaryotes as a result of enclosing their genetic information within the nucleus.

Solution

2) The new version of the old drug must be more effective. Escitalopram is having superior therapeutic properties than citalopram. We can cite the examples of drug like Sildenafil which was used in the late 1980’ s as an angina medication but now its released as Viagra, which is used to treat erectile dysfunction. Another example is Azidothymidine which failed as a chemotherapy drug but is now used as a treatment for HIV.

3)

a) The nuclear envelope which surrounds the nucleus is having a double membrane and has lots of pores on it. The pores play an important role on regulating the passage of macro molecules like protein and RNA. It permits the free passage of ions and water without any restrictions. Thus the membrane controls the information flow in the cell. The nucleus also maintains the integrity of the genes and aids in the regulation of gene expression.

b) In eukaryotes transcription and translation takes place in two different compartments. While transcription takes place in the nuclear compartment, translation takes place outside of the nuclear compartment. Compartmentalization helps to prevent translation of unspliced mRNA’s. If nuclues is not there the ribosomes will translate the RNAs which are not processed, resulting in the formation of impaired proteins.

c) The presence of the genetic material inside a separate compartment is advantageous for processes like nuclear division (for both mitosis and meiosis) to take place efficiently.