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Chapter 36
Vocabulary & Key Concepts
32
Biology
Undergraduate 1
03/19/2014

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Term
viruses are not made up of _____
Definition
cells
Term
viruses are not considered _____
Definition
organisms
Term
viruses cannot factor their own _____ or _____ or _____
Definition
ATP, amino acids, nucleotides
Term
viruses VS organisms: hereditary information
Definition
v: DNA or RNA; can be single stranded or double stranded
o: DNA; always double stranded
Term
viruses VS organisms: plasma membrane present?
Definition
v: no
o: yes
Term
viruses VS organisms: can carry out translation/transcription independently?
Definition
v: no
o: yes
Term
viruses VS organisms: metabolic capabilities
Definition
v: virtually none
o: extensive
Term
lateral gene transfer
Definition
shuttling genes from one organism to another
Term
epidemic
Definition
a disease that rapidly affects a large number of individuals over a widening area
Term
pandemic
Definition
an epidemic on a worldwide scope
Term
virulent
Definition
causes severe disease
Term
3 ways biologists study/characterize viruses
Definition
1. the structure of the extracellular infectious particle (virion)
2. the nature of the genetic material that is transmitted by virions from one host to another
3. variations in how viruses replicate
Term
2 general categories of viruses in terms of structure
Definition
1. those enclosed in only a capsid
2. those enclosed by both a capsid & an envelope
Term
positive-sense RNA virus
Definition
the genome contains the same sequences as the mRNA required to produce viral proteins
Term
negative-sense RNA virus
Definition
the base sequences in the genome are complementary to those in viral mRNAs
Term
ambisense RNA virus
Definition
the genome has at least one strand that contains two regions: one is positive sense & the other is negative sense
Term
replicative growth
Definition
a way that viruses infect the hose that produces the next generation of virions and often kills the host cell
Term
6 phases of replicative growth in virtually all viruses
Definition
1. attachment to a host cell & entry into the cytosol
2. transcription of viral genome & production of viral proteins
3. replication of the viral genome
4. assembly of a new generation of virions
5. exit from the infected cell
6. transmission to a new host
Term
bacteriophage
Definition
a virus that infects bacteria cells
Term
the lytic cycle ends with _____
Definition
destruction of the cell
Term
what is the receptor for HIV attachment?
Definition
CD4
Term
proteases
Definition
viral enzymes that cut polyproteins into individual proteins
Term
RNA replicase
Definition
a viral enzyme that functions as RNA-dependent RNA polymerases
Term
reverse transcriptase
Definition
a viral enzyme that transcribes from RNA to DNA
Term
retroviruses
Definition
viruses that reverse-transcribe their genome
Term
4 steps: lysogeny
Definition
1. viral genome enters host cell
2. viral genome integrates into host-cell genome
3. host-cell DNA polymerase copies chromosome
4. cell divides; virus is transmitted to daughter cells OR at any point after integration, the virus may activate the replicative cycle
Term
latency
Definition
the dormant state of viruses that infect animal cells
Term
transmission
Definition
the spread of pathogens from one individual to another
Term
emerging disease
Definition
a new illness that suddenly affects significant numbers of individuals in a host population
Term
strain
Definition
consists of populations that have similar characteristics & is the lowest level of taxonomy for viruses
Term
3 steps: generating new strains
Definition
1. two different strains of the same virus infect the same cell
2. replication produces a mix of strain-specific genomic segments in host cytoplasm
3. reassortment of genomic segments generates new, recombinant strains
Term
Baltimore classification system for distinguishing viruses
Definition
1. virion morphology
2. nature of the host species
3. type of disease resulting from infection
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