brainscape_flashcards_viruses
What are the structural features common to all viruses?
Small, fixed size; nucleic acid (DNA or RNA) as genetic material; capsid made of protein; no cytoplasm; few or no enzymes.
What is the size range of most viruses?
Most viruses are between 20 and 300 nm in diameter.
Do viruses grow?
No, viruses do not grow. They are assembled within the host cell and have a fixed size once assembled.
What kind of genetic material do viruses have?
Viruses can have either DNA or RNA, which can be single- or double-stranded.
What is a capsid?
A protein coat that encloses the genetic material of a virus.
Do viruses have cytoplasm or enzymes?
No, viruses lack cytoplasm and have few or no enzymes.
What is a retrovirus?
A virus that makes a double-stranded DNA copy of its RNA and then integrates it into the host genome.
What is the difference between enveloped and non-enveloped viruses?
Enveloped viruses are surrounded by a lipid bilayer when they bud from the host cell, while non-enveloped viruses are not and usually cause cell lysis when exiting.
Which types of cells do enveloped viruses usually infect?
Enveloped viruses usually infect animal cells.
How do non-enveloped viruses exit their host?
Non-enveloped viruses cause lysis (bursting) of the host cell when they exit.
What is the lytic cycle?
A viral life cycle where the virus takes over the host cell machinery to produce new viruses, eventually lysing (destroying) the host cell.
What is the lysogenic cycle?
A viral life cycle where the viral DNA integrates into the host genome and replicates with it, remaining dormant until triggered to enter the lytic cycle.
How does the viral DNA behave in the lytic cycle?
The viral DNA remains separate from the host genome.
How does the viral DNA behave in the lysogenic cycle?
The viral DNA integrates into the host genome as a prophage.
What happens to the host cell in the lytic cycle?
The host cell is lysed (destroyed) to release new viral particles.
