A bacteriophage is a virus that infects bacteria. They are not considered living (becuase they cannot replicate on their own) organisms, nor are they techincally considered non-living organisms. They are called obligate intracellular organisms, because they are parasites (kill the cell) that require a host in order to replicate.

Substance X would logically be released in the later part of viral infection. This would be referred to as a "late gene." The reason is that the virus needs time to replicate and assemble its progeny in the host. Lysing the cell immediately after infection would be futile since no progeny could be created. Lytic viruses use the lysis event to escape from the cell, so it cannot occur after viral release. Finally, lytic viruses typically do not integrate into the host chromosome, lysogenic viruses do.

The cell surface receptors that a virus recognizes and binds provides specificity for the organism(s) that it infects. Both lipopolysaccharides and teichoic acids are cell surface proteins of bacteria. Bacteriophages have very diverse mosaic genomes and replicate through both the lytic and lysogenic cycles. Retroviruses are RNA-positive strand viruses, which uses reverse transcriptase to synthesize DNA from an RNA template. Its DNA form of its genome is integrated into the host cell's genome.

溶原性感染是病毒进入the cell and incorporating its nucleic acid into the host genome. RNA viruses are capable of this type of infection, but must first have their RNA be converted to DNA using the enzyme reverse transcriptase. The DNA genome remains dormant in the cell as it undergoes cellular divisions, increasing the number of cells that contain the viral DNA. This stage is known as the latent period.

Eventually, the viral genome will be stimulated and enter into the lytic viral cycle. During this phase, the virus hijacks the cell ribosomes and produces large quantities of the viral genome and proteins. Eventually the virus causes the cell to lyse, releasing more virions into the host.

HIV is a retrovirus, meaning that it contains RNA as its genetic material, and thus reverse transcriptase to code for DNA from the RNA template. It also has a protein coat, and must use proteases in order to degrade the host cell membrane to inject its RNA. It does not, however, have ribosomes. It will eventually use the host ribosomes to translate its own genetic material.

The question addresses the Baltimore classification system for viral genetic information. Viruses contain some form of DNA or RNA, but never both.

Retroviruses carry RNA and when they infect a host cell, they use their own reverse transciptase to made DNA from that RNA; therefore, within the virus, there are only the molecules that make up RNA. Uracil is used in RNA place of thymine, which can be found in DNA. Cytosine, guanine, and adenine can be found in both DNA and RNA.

Neisseriasynthesizes proteins as a free living prokaryote. Viruses are generally dependent on host cellular machinery, and synthesize their proteins upon hijacking of a host ribosome.

所有的病毒包含蛋白质外套(或胶囊)that protects the genetic material (which can be either DNA or RNA). In some instances (such as herpes simplex), the virus can also contain an lipid envelope that serves as a membrane.

The correct answer is provirus. A retrovirus uses its own reverse transcriptase to synthesize DNA from its RNA. This DNA is then incorporated into the host genome via the integrase enzyme. The viral DNA in the host genome is referred to as a provirus; the host cell transcribes and translates the provirus to produce new copies of the virus, along with its own genome.