11 - viruses Flashcards
What is a virus?
A simple, miniscule, infectious, obligate, intracellular parasite comprising of genetic material surround by a protein coat and sometimes an envelope derived from a host cell membrane.
What is the difference between a virus and a virion?
Virion is the version of the virus outside of body, where as a virus is inside the body
What is the structure of a virus?
A nucleic acid surrounded by a protein coat called a capsid
What is the size of a virus?
20-300nm
What is the eclipse period?
The period in viral multiplication where the virus is constructing viruses and replicating, before the cell bursts
What is a virus capsid made of?
capsomeres
What are the three main shakes of viruses?
Helical - capsomers joined together in a spiral fashion
Polyhedral - a virus with a roughly spherical capsid
Binary (complex) - irregular or complex shapes
What are the functions of a viral capsid?
It protects the nucleic acid, allows the virion to attach to the host cell and provides proteins that enable the virion to penetrate the cell membrane
What is a naked virus?
A virus without an envelope
What hosts can viruses infect?
Bacteria (bacteriophages), animals, fungi, plant, algae, Protozoa and other viruses (virophage)
What are bacteriophages?
viruses that infect bacteria
What are the features of bacteriophages?
Binary capsid, tail fibres that allow for cohesion, a base disc that allows the virus to insert itself into the bacteria and most of them have dsDNA.
What is the lytic phase of a bacteriophage?
When the bacteriophage is virulent and kills the host
What happens in the temperate phase of bacteriophages?
After infection, the bacteriophage inserts it’s genome into a host’s genome, forming a prophage. This prophage then produces a repressor protein which inhibits lytic genes
What are three of the uses of bacteriophages
To kill certain bacteria, e.g. in those that spoil food
They produce enzymes which kill bacteria
They can be used to display antigens for use in vaccines
