Chapter 6: viruses

Question 1

Viruses

Answer 1

Infect all living organisms

Question 2

Characteristics of viruses

Answer 2

• microscopic (TEM or SEM)
• size (nm)—-> bacteria( 1000x)
• small genomes (2k-10kb) , bacteria ( 4.6 mb)
• lack metabolism (host is needed)
• shapes: helical filament our, icosahedral

Question 3

Capsid

Answer 3

Capsomers, come together spontaneously to form different capsid structures

Question 4

Isocahedral

Answer 4

-diamond shape (ex. HIV)
-20 sided
12 peaks/ points
- exhibits rotational symmetry

Question 5

Helical filamentous

Answer 5

(Ebola)

-thread like

Question 6

Viral structures

Answer 6

Naked, enveloped, complex

Question 7

Nucleic acid

Answer 7

Strandness
DS, SS RNA
DS, SS DNA

Question 8

Special enzymes

Answer 8

• reverse transcriptase
• rna polymerase
• dna polymerase
• spike genes
• neuramindase (release viruses from host cell)
• capsid

Question 9

Polarity

Answer 9

DNA, RNA
+RNA= ready for translation
-RNA= template for making more -RNA
- most be changed to +RNA and then be translated

Question 10

Viral classification

Answer 10

• envelope
• RNA/DNA
• strandness
• capsid structure
• genome size
• host range

Question 11

Multiplication (steps)

Answer 11

1. Absorption- spikes, envelope, and tail-fibers
2. Penetration- fusion, endosytosis or injection
3. Uncoating
4. Assembly
5. Release

Question 12

How to study viruses

Answer 12

• animal cells/ cell cultures/ eggs
• small living animals
• bacteriophage can be used as delivery systems ( genetically modified)

Question 13

Viroids

Answer 13

Viruses that don’t have cap side, but are very stable. 
-folded structure 
- infect plants
- replicated by host RNA polymerase 
Ex: tobacco mosaic viruses

Question 14

Prions

Answer 14

Infect Animals (ex. Mad cow disease)

• have no nucleic acid component
• alters conformation of other normal proteins

Question 15

Plaque assay

Answer 15

Way to see that bacteriophage has lysis cell