When do viruses reproduce

They may use an animal, plant, or bacteria host to survive and reproduce. As such, there is some debate as to whether or not viruses should be considered living organisms. A virus that is outside of a host cell is known as a virion. Not only are viruses microscopic, they are smaller than many other microbes, such as bacteria. Most viruses are only 20— nanometers in diameter, whereas human egg cells, for example, are about micrometers in diameter, and the E.

Viruses are so small that they are best viewed using an electron microscope , which is how they were first visualized in the s. Viruses generally come in two forms: rods or spheres. However, bacteriophages viruses that infect bacteria have a unique shape, with a geometric head and filamentous tail fibers.

No matter the shape, all viruses consist of genetic material DNA or RNA and have an outer protein shell, known as a capsid. There are two processes used by viruses to replicate: the lytic cycle and lysogenic cycle. Some viruses reproduce using both methods, while others only use the lytic cycle.

In the lytic cycle, the virus attaches to the host cell and injects its DNA. Then fully formed viruses assemble. These viruses break, or lyse, the cell and spread to other cells to continue the cycle. Like the lytic cycle, in the lysogenic cycle the virus attaches to the host cell and injects its DNA.

In humans, viruses can cause many diseases. For example, the flu is caused by the influenza virus. Typically, viruses cause an immune response in the host, and this kills the virus. Not to scale. Coronaviruses are hundreds of times smaller in width than human cells.

Cross section of a coronavirus. Spike protein. Coronavirus RNA. A poor fit. A good fit. Interior of host cell. Uncoating: The viral capsid is removed and degraded by viral enzymes or host enzymes releasing the viral genomic nucleic acid. Replication: After the viral genome has been uncoated, transcription or translation of the viral genome is initiated. It is this stage of viral replication that differs greatly between DNA and RNA viruses and viruses with opposite nucleic acid polarity.

This process culminates in the de novo synthesis of viral proteins and genome. Assembly: After de novo synthesis of viral genome and proteins, which can be post-transrciptionally modified, viral proteins are packaged with newly replicated viral genome into new virions that are ready for release from the host cell.

This process can also be referred to as maturation. Virion release: There are two methods of viral release: lysis or budding. Lysis results in the death of an infected host cell, these types of viruses are referred to as cytolytic. An example is variola major also known as smallpox. That way, they can adapt and survive in new environments. Eukaryote microbes can either reproduce sexually or asexually. Or both. An example of this is the nematode Caenorhabditis elegans.

During sexual reproduction, a male and a hermaphrodite lay next to each other. The male introduces sperm and fertilises the eggs of the hermaphrodite. But the hermaphrodite can also fertilise itself. Despite the ease of this asexual self-fertilisation, the hermaphrodite still prefers to be fertilised by a different male. This produces more offspring and more genetic variation in progeny.