F.2

Question 1

Life Characteristics (5)

Answer 1

• Metabolism
• Growth
• Responsiveness
• Control
• Organizational & Structural similarities: Genome + Barrier 4

Question 2

is a virus alive? what does it do and doesn’t do?

Answer 2

no it is not alive:
-Does not respire
-Does not display irritability
-Does not grow*
-Does reproduce
-Adapt to new hosts

Question 3

what does “bottom up” mean?

Answer 3

-simplest form capable of displaying the most essential attributes of an organism
* Replication + Adaptation

Question 4

new definition of an organism

Answer 4

the unit element of a continuous lineage with an individual evolutionary history

Question 5

life dependence of virus

Answer 5

-Cannot carry out metabolic activity
-Cannot reproduce independently
-No membrane bound organelles
-No lipid membrane*
-Do not grow in size or respond to direct environment
-Do not follow the Central Dogma

Question 6

Typical Virus are:

Answer 6

-Sub-Microscopic
-Acellular (No organelles)
-Nucleic Acid content (Amount/Type)
-Barrier (Capsid enclosure)
-Infectious
-Intra- & Extra-cellular states
-Virus/Virion

Question 7

states of viruses:

Answer 7

Extracellular (Virion):
* Possess a protein coat [capsid]: Capsid + Genome = Nucleocapsid
* Recognition for host: Infectious stage
* May possess a phospholipid cover [envelope]
Intracellular (Virus):
* No capsid present
* Replication stage

Question 8

taxa for viruses

Answer 8

-Order (-virales): highest currently recognized.
-Family (-viridae)
-Subfamily (-virinae)
» Genus (-virus)
* Species/Specific epithet (e.g.: hanta virus)

Question 9

taxonomic criteria for virus
GHP

Answer 9

1. Genome Structure
2. Host Organism(s)
3. Particle Morphology
   * Disease symptoms, antigenicity, protein profile, host range, etc. (familial if not generic level)

Question 10

viral genome options:
content?
strand?
how many?
arrangement?
decodability?

Answer 10

-DNA or RNA (never both*): Content is low
-Single-stranded (ss) or Double-stranded (ds)
-Multiple vs. Single
-Arrangement: Linear Molecules, Circular Molecules
-Decodability: Positive Sense, Negative Sense

Question 11

viral genome: decodability

Answer 11

Sense:
* Positive: Direct production of protein
Negative:
* Additional steps required to produce protein
* Usually complementary to template strand

Question 12

what can viruses infect?

Answer 12

-all cellular organisms can be infected: all 5 kingdoms (all 3 domains)
-infection is based on complementarity: surface antigens (proteins, glycoproteins)

Question 13

Virus families infecting two kingdoms of organisms are

Answer 13

-Bunyaviridae (animals and plants)
-Partitiviridae (plants and fungi)
-Reoviridae (animals and plants)
-Rhabdoviridae (animals and plants)
-Phycodnaviridae (protozoa and plants)
-Picornaviridae (plants and animals - tentative)
-Totiviridae (protozoa, fungi and insects- tentative)

Question 14

viral morphology:

Answer 14

-Average bacterial range: 1-4μm, Visualized via Light Microscopy
-Viral size: 10nm («400nm)

Question 15

capsid are:

Answer 15

-Virus/Virion: Nucleic Acid, Protein Coat (Capsid)
-Capsid:-
-Repetitive units of one or few proteins: Capsomeres
-Functions: Structural (Enclosure), Enzymatic
-Helical/Tube
-Spherical/Polyhedral
-Complex
-Binal (Phage)

Question 16

envelope of virus

Answer 16

-Viral Membranes: Similar composition to cellular membrane “Enveloped viruses”
-Host-acquired: With (Enveloped), Without (Non-
enveloped or Naked)
-Viral protection mechanism

Question 17

viral types (order)

Answer 17

-Ligamenvirales: infecting archaea
-Caudovirales: dsDNA bacteriophages
-Herpesvirales: large eukaryotic dsDNA viruses
-Ligamenvirales: dsDNA archaean viruses
-Mononegavirales: nonsegmented (-) strand ssRNA plant and animal viruses
-Nidovirales: (+) strand ssRNA viruses with vertebrate hosts
-Picornavirales: small (+) strand ssRNA viruses that infect a variety of plant, insect and animal hosts
-Tymovirales: (+) ssRNA viruses that infect plants

Question 18

basic stages of virus

Answer 18

1. Attachment: Locate and stick
2. Entry: Getting in
3. Synthesis: Making pieces
4. Assembly: Putting it together
5. Lysis: Getting out

Question 19

lytic replication: prokaryotes

Answer 19

-Depend on hosts for life cycle:
* Enzymatic reaction: Ribosomal protein production, Replication mechanisms
-5 Characteristic steps:
* Attachment
* Entry
* Synthesis
* Assembly
* Lysis

Question 20

bacteriophages: attachment

Answer 20

-Random collision of bacterium and phage
-Attraction between phage “tail fibers” and
proteins on bacterium: Cell wall, Flagellum, Pilus

Question 21

bacteriophages: entry

Answer 21

-Overcoming of cell wall and membrane
-Penetration via:
* Perforation: Digestive enzymes (Lysozyme)
* Injection: Hollow tube
* Host override: Enzymes halt host metabolism

Question 22

bacteriophages: entry expanded

Answer 22

Getting in:
-Variation on host type (Prokaryotic, Eukaryotic)
-Capsid morphology: Naked, Enveloped
Methods:
*Direct Penetration: Naked viruses, Perforation on cell barriers
*Membrane Fusion: Enveloped, Membrane layer
interaction
*Endocytosis: Enveloped, Host-cell eating triggered (Uncoating)

Question 23

bacteriophages: synthesis

Answer 23

Overcoming of bacterial system:
*Entry of viral blueprint: DNA or RNA
*Entry of viral enzymes: Lysozyme destroys bacterial system, Polymerases replicate genome
*Bacterial system forced to produce viral system: Genome, Components

Question 24

bacteriophages synthesis explained

Answer 24

Expression:
*Entry: Genetic Material, Accessory proteins
* Blueprint: May create needed proteins, Serves as template
*Proteins: May adapt genetic material, Replicate genetic material, Support in integration into host genome
Replication:
*Genetic material copied
*Genetic material adapted for copying
*Cell-type variation:
* Eukaryotes: Nuclear transcription & Assembly, Cytosolic Translation
*Prokaryotes: All cytosolic

Question 25

bacteriophages: release

Answer 25

-Completion of destruction of cell wall and membrane by lysozyme
-Bacterium is destroyed: Lysed or Eaten (BacterioPHAGE)
-Cycle:
-Time from Attachment to Release. (Burst time)
-Quantity: Burst size

Question 26

specialized replication: lysogeny
-what is it?
-when?
no? instead?
-suppresses?
-interpretation into?
resuming of?

Answer 26

-Modification of replication in bacteria
-Post-entry
-No-synthesis → Prophage (Dormant/inactive)
-Suppression of other viral genes
-Integration into bacterial genome: Bacterial replication multiplication, Possible bacterial modification (New Toxic bacteria:Cholera, Diphtheria, Rheumatic fever)
-Resuming of viral cycle: Induction

Question 27

eukaryotic viruses
similar?
variations (NVT)

Answer 27

-Similar steps
-Variations:
* No cell wall
* Viruses with envelopes
* Types of genetic material

Question 28

eukaryotic viruses: assembly and release and budding

Answer 28

-Similar Assembly methods: Nuclear or Cytosolic
-Release: By Budding With Envelope or Without Envelope
-By Lysis: ~Lytic Cycle

Question 29

eukaryotic viruses:
what is it?
what is latency?
what is lysogeny aka?
vs?
possible?

Answer 29

-Nutritional and biosynthetic requirements for cells are the same for a virus and its host
*Latency: When a virus is present in the body but exists in a resting (latent) state without producing more virus
~ lysogeny (known as temperate phage or prophage)
-Provirus vs. prophage
-Possible permanent integration into genome vs. guaranteed prophage integration (Lack of induction)

Question 30

oncogenesis: cancer review
what is it?
recall?
genes involved in? are?
what may disrupt genetic control?

Answer 30

-Abnormal Cell Division
-Recall: Mitosis & Meiosis (Neoplasia/Tumorigenesis), Under genetic control (Activators / Repressors)
-Genes involved in control of division: Protooncogenes, Oncogenes, TSGs
-Viral lysogeny/latency may disrupt genetic control

Question 31

parasite needs:

Answer 31

-Hosts: Standardized cells optimized for viral
replication
-Media types: Mature organisms, Fertilized eggs, Tissue culture
-Mature organisms: Living (Bacterial lawns, Plants and Animals)
-Eggs: Embryonated eggs (Large contained, sterile cells, self-sustained)
-Tissue Culture: Primary, Stable

Question 32

further exceptions to the dogma: viroids + prions

Answer 32

Smaller RNA pieces:
*Viroids: Non-capsid, Circular RNA, Extremely small, Infectious particles, Found in plants
*Viroid-like agents: Same idea, Found in fungi
Infectious proteins:
* Prions: Nucleic acid-independent reproductive proteins, Protein based, Protein-reshaping, Genetic predisposition, Heat-resistant
*Neurological disorders (TSE): BSE, Scrapie, Kuru, CJD, CWD