What is a virus?
A virus is a microscopic infectious agent that can only replicate inside the living cells of an organism. Unlike cells, viruses do not have cellular structures; they consist of genetic material (either DNA or RNA) encased in a protein shell called a capsid. Some viruses may also have an outer lipid envelope. Viruses can infect a variety of organisms, including animals, plants, and bacteria.
How does a virus reproduce?
Viruses reproduce through a process called the lytic cycle or the lysogenic cycle.
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Lytic Cycle: The virus attaches to a host cell and injects its genetic material. The host cell's machinery is then hijacked to replicate the virus's genetic material and produce viral proteins. Once the new virus particles are assembled, they burst out of the host cell, destroying it in the process and infecting new cells.
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Lysogenic Cycle: In this cycle, the virus integrates its genetic material into the host cell's genome and can remain dormant for a period of time. The viral genetic material is replicated along with the host's DNA when the cell divides. Environmental triggers can then activate the viral DNA, initiating the lytic cycle.
What are 2-3 differences between a virus and a cell or multicellular organism?
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Structure: Viruses lack cellular structures; they are made up of genetic material and a protein coat, while cells have a complex structure including a nucleus, cytoplasm, and various organelles.
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Reproduction: Cells can reproduce independently through cellular division (mitosis or meiosis), whereas viruses cannot reproduce on their own and must infect a host cell to replicate.
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Metabolism: Viruses do not have metabolic processes; they do not consume energy or produce waste. Cells, on the other hand, have metabolic pathways that allow them to convert nutrients into energy and perform various life functions.
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