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40 Cards in this Set

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Intracellular form of a virus
1. Obligate intracellular parasites
2. Most likely to cause disease in host
Extracellular form of a virus
1. When outside of host in transit (virons)
2. The metabolically inert form (no replication or biosynthesis)
General properties of Viruses
1. Genetic elements
2. Highly abundant in nature
3. Exist in two forms:
infective intracellular form and transmission extracellular form
Genome
1. Contains either DNA or RNA genomes
2. EIther single or double stranded
3. Linear or circular in shape
4. Genome typically used in viral classification
Bacterial hosts
Bacteriophages
Animal hosts
Prions
Plant hosts
Viroids
The protein shell that surrounds the nucleic acid of the virus is called the __________
capsid
Virus with no membrane coverage
Naked virus
Virus with a lipid bilayer membrane
Enveloped virus
General Features of Viral Replication
1. Attachment
2. Penetration
3. Synthesis
4. Assembly and Packing
5. Release
Latent period
Eclipse + Maturation
Burst size
number of virions released
Baltimore
developed classification scheme for viruses based on relationship of viral genome to its mRNA
Baltimore Classification Scheme
Class 1
dsDNA viruses
Baltimore Classification Scheme
Class 2
ssDNA viruses
Baltimore Classification Scheme
Class 3
dsRNA
Baltimore Classification Scheme
Class 4 & 5
ssRNA (+ or -)
Baltimore Classification Scheme
Class 6
retroviruses (HIV)
Baltimore Classification Scheme
Class 7
dsDNA viruses that replicate through an RNA intermediate
The most studied and common type of bacteriophage
ds DNA viruses
RNA-containing bacteriophages
1. ss MS2 virus (naked)
2. ds 6 virus (enveloped)
Characteristics of MS2 virus
1. infects E. coli cells
2. positive strand RNA genome
3. icosahedral symmetry
4. naked
MS2 genome encodes only four proteins:
1. Maturation protein
2. Coat protein
3. Lysis protein
4. RNA replicase
DNA-containing Bacteriophages
1. ss DNA genome
2. ds DNA genome
ss DNA genome
1. Icosahedral symmetry
2. Filamentous symmetry
ds DNA genome
T2, T7, Mu, and Lambda viruses
Mu (Mutator) Virus
Mutator Phage
induces mutation in host genome
Temperate bacteriophage pathways
1. Lytic Pathway
2. Lysogenic Pathway
Lytic Pathway
1. Conquer of host genetic materials
2. Release of mature viruses from host
3. More potent
Lysogenic Pathway
1. Integration of viral DNA into host DNA
2. Production of lysogenized cell - harboring of viral genes by host possible without harm
Viruses of Domain Archaea
1. All have unusual morphologies
2. All have dsDNA
3. All have small genomes
4. Resistant to conditions in extreme environments
Lytic infection
the destruction of host cells
Persistent infection (acute)
live and actively produced viral cells in host
Latent infection
chronic symptomatology
Tumorgenesis or Transformation
tumor or cancer formation
Retroviruses
Contains an RNA genome that is replicated through a DNA intermediate
*First viruses shown to cause cancer!!
Replication of Retroviruses
1. Entrance into host
2. Uncoating of envelope
3. Reverse transcription
4. Integration into host genome
5. Transcription
6. Assembly and encapsidation (production of nucleocapsids)
7. Budding (release of enveloped cells)
Viroids
1. Small, circular ssRNAs
2. Causes many plant diseases
Prions
1. Contains no nucleic acid
2. Causes various animal diseases