Can viruses cause genetic mutations?
Can viruses cause genetic mutations?
Virus-induced gene mutations are probably due to insertions of fragments of viral DNA (or cDNA) into the host chromosomes; at least some of these mutations are capable of transpositions and reversions.
Which type of viral infection causes the host cell to lyse or burst?
Bacteriophage infections Bacteriophages, just like other viruses, must infect a host cell in order to reproduce. The steps that make up the infection process are collectively called the lifecycle of the phage. Some phages can only reproduce via a lytic lifecycle, in which they burst and kill their host cells.
Can a host cell be damaged by a virus?
A virus must use cell processes to replicate. The viral replication cycle can produce dramatic biochemical and structural changes in the host cell, which may cause cell damage. These changes, called cytopathic (causing cell damage) effects, can change cell functions or even destroy the cell.
How do pathogens exit the body?
Portals of exit is the means by which a pathogen exits from a reservoir. For a human reservoir, the portal of exit can include blood, respiratory secretions, and anything exiting from the gastrointestinal or urinary tracts.
What is the role of the host cell in a viral infection?
Viruses depend on the host cells that they infect to reproduce. When found outside of host cells, viruses exist as a protein coat or capsid, sometimes enclosed within a membrane. The capsid encloses either DNA or RNA which codes for the virus elements.
What are 3 cytocidal effects produced by viruses?
Cytocidal Infections Morphologic Effects: The changes in cell morphology caused by infecting virus are called cytopathic effects (CPE). Common examples are rounding of the infected cell, fusion with adjacent cells to form a syncytia (polykaryocytes), and the appearance of nuclear or cytoplasmic inclusion bodies.
How does a virus affect the host cell?
A virus must use its host-cell processes to replicate. The viral replication cycle can produce dramatic biochemical and structural changes in the host cell, which may cause cell damage. These changes, called cytopathic effects, can change cell functions or even destroy the cell.
What kind of virus infects plant cells?
Viruses that infect plant or animal cells may also undergo infections where they are not producing virions for long periods. An example is the animal herpesviruses, including herpes simplex viruses, the cause of oral and genital herpes in humans.
How is a virus fixed to a cell?
(a) The virus (or viral component) – complement – antibody complex is fixed to a cell, usually an erythrocyte or leukocyte or platelet, resulting in complement-dependent cell lysis.
How does a virus replicate in a permissive cell?
The permissive cell must make the substances that the virus needs or the virus will not be able to replicate there. A virus must use cell processes to replicate. The viral replication cycle can produce dramatic biochemical and structural changes in the host cell, which may cause cell damage.
How are viruses able to infect other cells?
After penetration, the invading virus must copy its genome and manufacture its own proteins. Finally, the progeny virions must escape the host cell so that they can infect other cells. Viruses can infect only certain species of hosts and only certain cells within that host.
How are viruses and cancer related to each other?
Viruses and cancer. Some viruses alter the DNA of their host cells in a way that helps cancer develop. Some viruses, such as herpesviruses and HIV, leave their genetic material in the host cell, where the material remains dormant for an extended time (called latent infection).
How does a virus get genetic information from its host?
This also provides a means to insert foreign material into a gene (figure 2). Recombination enables a virus to pick up genetic information from viruses of the same type and occasionally from unrelated viruses or even the host genome (as occurs in some retroviruses – see retroviruses ).
What kind of infections can a retrovirus cause?
RNA viruses, particularly retroviruses, are prone to mutate. Some viruses do not kill the cells they infect but instead alter the cell’s functions. Sometimes the infected cell loses control over normal cell division and becomes cancerous. Some viruses, such as hepatitis B virus and hepatitis C virus, can cause chronic infections.