1+2: significance, morphology Flashcards
What is a Virion
the complete, infective form of a virus outside a host cell, with a core of RNA and a capsid.
Characteristics of Virion:
- Insert particles transferring genetic information
- Size: 20-300 nm: Only EM!
- Shape: high variety
- Content: NA (DNA or RNA), protein, +/- lipid
Vegetative virus:
the infected cell
What is a Obligatory cell parasite?
An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce.
What are the two forms of existence?
- Virion
- Vegetative virus
Occurrence of viruses:
- Widespread: bacteria, fungi, plants, animals, human hosts
- every human carries 2.5 viruses
- Active virus multiplication in 1-3% of the people
How many accepted species does the International Commitee on Taxonomy of Viruses have?
5630
What is ment by Quasispecies character?
the species concept has limitations by viruses
What is Metagenomic studies?
Identification of NA in environmental samples. 125000 different viral DNA sequences were identified.
What does Orphan virus mean?
Not pathogenic: Only infection, but no disease
The origin of viruses
- Most viruses of eukaryotes probably have been evolved from prokaryotic viruses (bacteriophages)
- they do not fit into the phylogenetic tree of living creatures
What is the Cell degeneration theories of the Origin of the virus?
Cell degeneration (= Chlamydia, Rickettsia): the parasite cell lost its independence. Outside of the cell only carries the information -> complicated viruses (i.e poxviruses)
What is the Runaway cell components theories of the Origin of the virus?
- mRNA –> +ssRNA virus
- Chromosome fragment –> dsDNA virus
Morphology of viruses is determined by?
the capsid
What is a Capsid?
Morphologically defined protein coat
