Viruses Flashcards
Viruses ?
A particle that infects cells of organisms.
Nonliving organism
Not composed of cells
Cannot replicate without host cell
Nucleic Acid ?
- RNA or DNA
- ss (single stranded) or ds (double stranded)
Capsid
Protein coat
Envelope
Coat of host cell membrane.
Sometimes there.
Protection : makes it harder to detect
Virus classification (5)
Size and structure
Method of nucleic acid replication (depends on
Bacteriophages
Virus that infects bacteria
Lytic Cycle
Common for viruses and its their main goal. Eventually all viruses do this.
1) Attachment
2) Penetration
3) Replication (copy nucleic acid) and Synthesis (make protein to build more capsids)
4) Assembly
5) Release
Lysogenic Cycle
1) Attachment
2) Penetration
3) Integration : put viral nucleic acid (DNA) into host cells DNA
4) Replication (copies Prophage)
- Eventually leads to assembly and release
Viroids
- short RNA chains (<300 nucleotides)
- no capsids
- plant pathogens
- not virus but virus like
Prions
- misfolded proteins
- cause transmissible spongiform enciphalopathies (brain disease) example; mad cow disease
- degenerative nervous system
- not a virus but virus like
Pox viruses
- dsDNA
- Envelope
- Large, complex viruses; replicate in cytoplasm of host
- Smallpox, cowpox, monkeypox, and economically important diseases of domestic fowl
Herpes viruses
- dsDNA
- Envelope
- medium to large; replicate in host nucleus
- cold sores, genital herpes, a STD, chickenpox, shingles
Adeno virus
- dsDNA
- No envelope
- replicate in the host nucleus
- Respiratory tract disorders (sore throat, tonsillitis), conjunctivitis, and gastrointestinal disorders are caused by more than 40 adenoviruses in humans, others varieties infect animals
Papova viruses
- dsDNA
- No envelope
- Human warts and some degenerative brain diseases; some cancers including cervical cancer
Parvo viruses
- ssDNA
- No envelope
- Some require a helper virus in order to multiply
- Infections in dogs, swine, arthropods, rodents; gastroenteritis in humans (transmitted by eating infected shellfish)
Toga viruses
- ssRNA can serve as mRNA
- Envelope
- Large diverse group of medium sized
- may be transmitted by arthropods
- Rubella (German measles)
Orthomyxoviruses
- ssRNA can serve as template for mRNA synthesis
- Envelope
- medium sized that often exhibit projecting spikes
- Influenza (flu) in humans and other animals
Paramyxovirus
- ssRNA
- resemble orthomyxoviruses but somewhat larger
- Rubeola (measles) and mumps in humans; distemper in dogs
Rhabdoviruses
- ssRNA
- Envelope
- Rabies
Corona viruses
- ssRNA
- Envelope
- Upper respiratory infections; SARS
Flaviviruses
- ssRNA
- Envelope
- Yellow fever, West Nile virus, hepatitis C (the most common reason for liver transplants in the US)
Folio viruses
- ssRNA
- Envelope
- Hemorrhagic fever, including that caused by the Ebola virus
Bunya viruses
- ssRNA
- Envelope
- St. Louis encephalitis; hantavirus pulmonary syndrome (caused by Sin Nombre virus , a hantavirus)
Retro viruses
- ssRNA
- Envelope
- Viruses that contain reverse transcriptase for transcribing the RNA genome into DNA; two identical molecules of ssRNA
- AIDS; some types of cancer
Picornaviruses
- ssRNA can serve as mRNA
- No envelope
- Diverse group of small viruses
- Polio, Hepatitis A, Intestinal disorders (Enteroviruses), common cold (Rhinoviruses), aseptic meningitis (Coxsackievirus, echovirus)
Reovirus
- dsRNA
- No envelope
- Vomiting and diarrhea; encephalitis
