Chapter 19: Viruses Flashcards
An infectious particle consisting of genes packaged in a protein coat
Virus
T/F: viruses are more complex in structure than prokaryotic cells
F: much simpler
T/F: Viruses cannot reproduce or carry out metabolism outside of a host cell
T: They are dependent on the host cell
T/F: Viruses are cells
F: Viruses are not cells; they are very small infectious particles
What do viruses consist of?
Nucleic acid enclosed in a protein coat, and some cases, a membranous envelope
Viral genomes consist of which 2 things?
Double/single stranded DNA or double/single stranded RNA
Viruses are classified as which two kinds of viruses?
DNA or RNA
A genome can be what two kinds of shapes of single molecule of nucleic acid?
Linear or circular
How many genes do viruses have in their genome?
Between 3 and 2,000
The protein shell that encloses the viral genome
Capsid
Capsids are built from protein subunits called _______
Capsomeres
What are the two types of main structures of viruses that are associated with capsid?
Helical or icosahedral
Accessory structures that help viruses infect hosts
Protein spikes
Derived from membranes of host cells and surround the capsids of influenza viruses and many other viruses found in animals
Viral envelopes
Contain a combination of viral and host cell molecules
Viral envelopes
Viruses that infect bacteria; AKA “Phages”
Bacteriophages
Have elongated capsid head that encloses their DNA
Bacteriophages
T/F: Viruses replicate only in host cells
T: viruses are obligate I trace lunar parasites; can replicate only within a host cell
A limited number of host species that can infect
Host range
How does a viruses replicate?
Utilizes the cell’s machinery to reproduce
What are the best understood of all viruses?
Phages
What are phage’s two alternative reproductive mechanisms?
Lytic and lysogenic cycle