Virus Flashcards
What is a virus?
What are they composed of?
Particles of nucleic acid, protein and sometimes lipids.
Can only reproduce by infecting living cells.
Typical virus composed of DNA or RNA core surrounded by a protein coat.
What is a capsid?
a virus’s protein coat is known as a capsid, which allows a virus cell to enter a host cell.
Define a lytic infection.
When a virus enters a cell, makes copies of itself and then causes the cell to burst.
What is a bacteriophage?
Viruses that infect bacteria.
Define a lysogenic infection.
When a virus embeds its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell’s DNA.
What is a prophage?
The viral DNA that is embedded in the host’s DNA.
What is a retrovirus?
A virus that contains RNA as its genetic information.
What is viral specificity?
Viruses tend to infect certain cells. Plant viruses infect plant cells, most animal viruses infect only certain related species of animals, bacteria viruses infect only certain bacteria.
Where can a virus reproduce?
Only in a host cell.
Why does a virus need a host to survive and reproduce?
Why can they be considered parasites?
It lives off of the host cells nutrition, respiration and other important functions.
Viruses can be considered parasites because they depend on the host, but also harm it in the process.
What are the steps of a lytic infection?
Bacteriophage injects DNA into bacterium.
Bacteriophage DNA forms a circle.
Bacteriophage takes over metabolism, causing new bacteriophage proteins and nucleic acids to form.
Bacteriophage proteins and nucleic acid form full bacteriophage.
Cell lyses (bursts) and releases new bacteriophages.
What are the steps of a lysogenic infection?
Bacteriophage injects DNA into bacterium.
Bacteriophage DNA forms a circle.
Bacteriophage merges into bacterium DNA.
Bacteriophage DNA (prophage) replicates with bacterium.
Prophage exits bacterium’s DNA and enters the lytic cycle.
