Bacteria_Essay

It appears as if, when the virus was added, it resulted in an exponential decline in the bacteria population and an exponential increase in the virus population due to the lytic cycle (in which the virus reproduces by killing the host bacteria). However, after a certain time, the virus lost its ability to destroy the bacteria. This may have occurred for a variety of reasons. First, the viral DNA may have entered the bacteria genome and is dormant (lysogenic cycle). Second, the bacteria may have evolved by natural selection. Those bacteria resistant to the virus, whether it be by restriction enzymes or another means, survived and the viral population can no longer reproduce as rapidly, causing its population to level off. The protein capsid attaches to the host cell, releasing its DNA. The DNA may enter the host DNA as a prophage, entering the lysogenic cycle. Eventually, the viral DNA exits the host chromosome, and enters the lytic cycle. In the lytic cycle, the viral DNA uses host cell machinery (RNA polymerase, tRNA, etc..) to produce an mRNA transcript and eventually viral proteins that form the capsid for new viruses. The DNA is copied with DNA polymerase, and the newly formed viruses burst the host cell, killing it and releasing new viral copies to infect other cells. HIV is a retrovirus that carries RNA as its genetic material. The envelope glycoproteins enable the virus to bind to specific receptors on certain white blood cells. The virus fuses with the cell’s plasma membrane. The protein capsid binds to the host cell, are then removed, and releases its RNA along with an enzyme called reverse transcriptase. This enzyme is used to use the RNA as a template for creating a complementary DNA sequence. This DNA then enters the bacterial genome as a provirus and remains dormant. The DNA is then transcribed from time to time, and produces viral proteins. Proviral genes are transcribed into RNA molecules, which serve as genomes for the next viral generation and as mRNAs for translation into viral protein, including capsid proteins, reverse transcription, and envelope glycoproteins. Vesicles transport the glycoproteins to the cell’s plasma membrane and capsids are then assembled around viral genomes and reverse transcriptase molecules. Finally, new viruses bud off from the host cell.