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viruses
lack organelles, cytoplasm , nucleus Acellular obligate
intracellualr parasites: only reproduce inside a living host
cellLack ribosomes and metabolic processes
TERM 2
viral host range
DEFINITION 2
what organisms a virus can infectmost virus have a narrow
host range depends on a capsid structure
TERM 3
Tissue tropism
DEFINITION 3
most viruses only infect specific cells tissue in a multicellular
animal
TERM 4
Transmission
DEFINITION 4
can be through direct or indirect contact E.G HIV
TERM 5
Mechanical vector
DEFINITION 5
Virus carried passively on surface and transferred by physical
contact
Biological vector
Virus carried inside vector - ArthropodTransmitted by biting
Example Mosquito
TERM 7
Virus structure
DEFINITION 7
Viron - viral particlesize ranges from 20nm-900nm
TERM 8
2 components found in all viruses
DEFINITION 8
1. Nucleic acid core a viral genome Either DNA or RN Can be
SS, ds, circular, linear, can be separate segment2. Capsid is a
coating made of proteinFunction: provide shape and
protective covering
TERM 9
nucleocapid
DEFINITION 9
Nucleic acid + capsid Capsomeres individual protein
subunits
TERM 10
Spikes
DEFINITION 10
Proteins that facilitate attachment to penetration of host
cellGlycoprotein extension of the capsid or envelope Expose
proteins on the outside of envelop
Helical
Round circle represent capsid Tobacco Mosaic virus
TERM 17
Polyhedral
DEFINITION 17
Human Rhinovirus HRV14 (Icosahedral) causes common cold
TERM 18
Complex
DEFINITION 18
Combination of helical and polyhedral symmetryVariola Virus
T-even Bacteriophage
TERM 19
viral classification and taxonomy
DEFINITION 19
1. Classification based on genome DNA VS RNA SS or ds
DNASS or ds RNA (+) or (-) strand RNASegmented Vs
nonsegmented genome2. other : Presence/ absence of
envelope , host specificity, tissue specificity and shape
TERM 20
- RNA
DEFINITION 20
Cannot act as a messenger MRNA
+RNA
Can directly act as MRNACan be used directly to translate
viral proteins
TERM 22
MRNA
DEFINITION 22
Translated to become protein
TERM 23
Bacteriophage
DEFINITION 23
Phage virus that infects bacteria
TERM 24
Two types of bacteriophage
DEFINITION 24
1. Virulent phage 2. Temperature phage
TERM 25
Virulent phage
DEFINITION 25
Leads to immediate death lysis (lytic cycle)Cell death
Attachment
The phage attaches to the surface of host
TERM 32
Penetration
DEFINITION 32
The viral DNA enters the host cell
TERM 33
Biosynthesis
DEFINITION 33
Phage DNA replicates and phage proteins are made
TERM 34
Maturation
DEFINITION 34
New phage particles are assembled
TERM 35
Lysis
DEFINITION 35
The cell lyses releasing the new mage phages and cell dies
Bacteriophage Lysogenic cycle
Temperate phage temperate becomes a part of host cell
chromomosome1. Attachment and Penetration : The phage infects the
cell2. Integration: The phage DNA becomes incorporated into host
genome - virus hide into host cell The cell divides and prophage DNA is
passed on to to Daughter cells 4. Excision Induction : Under stressful
conditions the prophage DNA is exercised from the bacterial chromosome
and enters the Lytic cycle 5. Biosynthesis : Phage DNA replicates and
phage proteins are made 6 : Maturation: New phase particles are
assembledLysis / Release : The cell lyses, releasing the newly made
phages
TERM 37
Prophage
DEFINITION 37
Phage DNA incorporating into host chromosome
TERM 38
Transduction
DEFINITION 38
Transfer of DNA from one bacterium to another via a
Bacteriophage One way in which genetic recombination can
occur in bacteria
TERM 39
Two types of transduction
DEFINITION 39
1. General Transduction2: Specialized Transduction
TERM 40
General Transduction
DEFINITION 40
Happens during a lytic cycle (cell dies ) Transfer random
fragments of bacterial chromosome Transfer of a restricted
set of bacterial genres
Persistent Viral
infection
Virus stay in certain tissue organs of infected person Virus
remains in host in specific tissue and organsCould be a silent
infectionProductive infection that doesn't harm the
hostHerpes, Hepatic C, HIV
TERM 47
2 types of persistent infections
DEFINITION 47
1. Latent infection2. Chronic infection
TERM 48
Latent
infection
DEFINITION 48
Virus stay hidden or dormant inside the cell E.g cold sores,
Chicken pox-shingles
TERM 49
Chronic
infection
DEFINITION 49
Disease with symptom that are recurrent or persistent over a
long timeE.g Hepc , HIVHave an infection with symptoms that
persist over a long time periodOccurs when the body can't
eliminate the virus
TERM 50
Viral Culture
DEFINITION 50
All viruses must be grown inside host cellsBacteriophage -
grown with bacteriaAnimal viruses - Grown in tissue culture
cells or embryonated eggs
Liquid medium
only cannot be used to culture viruses
TERM 52
Viroids
DEFINITION 52
Very small pieces of RNA capable of self-replicationCause
disease in plants RNAs dont code for proteinsNot understood
how viroids replicate May cause disease by inactivating
cellular RNAsEx. Potato spindle tuber viroid - Potato infected
by PSTV
TERM 53
Virusoids
DEFINITION 53
Non-self replicating RNAs Genome is circular and SSOnly 220-
388 nt Found in plants Can only replicate if host cell infected
with helper virus
TERM 54
Prions
DEFINITION 54
they are a rogue form of protein PRP Infectious agents that
donot have nucleic acid Proteinaceous infectious particle
TERM 55
Infection proteins
DEFINITION 55
No nucleic acids are present
Sporadic CJD (Cruetzfeid-Jacob
disease)
Possible Somatic mutation Normal brain CJD brain Normal
brain tissue Sponge-like lesions in the brain tissue of a CJD
patient
TERM 62
Variant CJD
DEFINITION 62
Secondary bloodborne transmission contaminated cattle
products
TERM 63
Familial CJD
DEFINITION 63
Mutation in germline, Prp gene
TERM 64
Iatrogenic CJD
DEFINITION 64
Contaminated neurosurgical instruments hormoneCorneal
graft,gonadotrophic Secondary by blood transfusion
TERM 65
Kuru
DEFINITION 65
Cannibalism
Gerstmann
Mutation in germline Prp gene
TERM 67
human TSEs
symptoms
DEFINITION 67
Dementia, weakened muscle, loss of balanceNo cure: Death
in a few months - several years
TERM 68
2 types of prion proteins
DEFINITION 68
PrPsc - Abnormal prions ( Folded improperly)PrPc normal
cellular prions found on neurons
TERM 69
Mechanisms of prion action
DEFINITION 69
PrPsc - interacts with PRPc on normal PrPc on neuron
converted to PRpscNewly formed PRPsc converts more Prpcs
TERM 70
Prpcs
DEFINITION 70
This causes neuronal cell death results in holes in brain
tissue
