Viruses

Question 1

1. Viruses- cause most diseases that plague the world
2. Viroids
3. Prions

Answer 1

Acellular pathogens

Question 2

Not made of cells
Have DNA or RNA genome
Can’t carry out metabolic pathways
Neither grow or respond to environment
Cannot reproduce independently
Are active only inside a host & inactive outside

Answer 2

Characteristics of viruses

Question 3

This is limited with each virus
They have limited # of organisms it can
infect
Depends on host cell receptor molecules

Answer 3

Host range

Question 4

Specific Tissues they can infect
Depends on host cell surface receptors

Answer 4

Tissue tropism

Question 5

Use host cell functions to reproduce
Mutate quickly

Answer 5

Viral treatment

Question 6

1. Genome
2. Capsid (protein coat)
3. Enveloped vs non-enveloped

Answer 6

Virus structure

Question 7

Genetic make up
Chromosomes are made of either DNA or RNA (either but never both)
double or single stranded
Circular or linear
+, - sense or both

Answer 7

Genome

Question 8

Has code/template - code for gene/protein
Ready to go to the ribosome

Answer 8

Positive sense strand

Question 9

Opposite copy for a code for a gene
Copied back to mRNA

Answer 9

Negative sense strand

Question 10

Protective layer around nucleic acid
Shapes: icosahedral, filamentous, complex, amorphous

Answer 10

Capsid (protein coat)

Question 11

Some animal viruses have a membrane outside of the capsid
Derived from prior host
Viruses w/ out membrane = naked virus

Answer 11

Envelope vs non-enveloped

Question 12

Protect genetic material & gain entry to host cell
Made up of capsomeres which are proteins (repeating)

Answer 12

Capsid

Question 13

Bacteriophage

Answer 13

Virus that infects bacteria

Question 14

Shape of viruses with an envelope

Answer 14

Filamentous
Icosahedral

Question 15

DNA or RNA
single or double stranded
+ or - sense
Linear or circular
Special enzymes

Answer 15

Classification of viruses

Question 16

Generates new strains of a virus that can cause serious disease
Change in protein spikes
“Slight”

Answer 16

Antigenic drift

Question 17

1. Host recognition
2. Genome entry
3. Synthesis
4. Assembly
5. Exit and transmission

Answer 17

Virus reproduction

Question 18

Replication cycles in a bacteriophage

Answer 18

Lytic cycle
Lysogenic cycle

Question 19

Immediate/short
Rupture of host cell
Transcribes it’s DNA & produces enzymes & capsid

Answer 19

Lytic life cycle

Question 20

Long
Phage genome integrates into host DNA= prophage
Replicated along with host cells

Answer 20

Lysogenic life cycle

Question 21

May occur as a result of viral infection

Answer 21

Transduction

Question 22

What is evidence of bacteriophage activity?

Answer 22

Plaque

Question 23

Animal virus replication

Answer 23

8-36 hours
Larger variety of genomes

Question 24

No tails or tail fibers
No cell wall
Have protein/sugar spikes

Answer 24

Animal virus: attachment

Question 25

Take off capsid and release viral genome into host cell

Answer 25

Animal virus: entry/uncoating

Question 26

Capsid stays on outside & viral genome is squirted inside No uncoating

Answer 26

Direct penetration

Question 27

Fuses with host cell cytoplasmic membrane & capsid broke down & releases viral genome in cytoplasm Uncoating

Answer 27

Membrane fusion

Question 28

Glycoprotein spikes fuse/ bind w/ receptors on outside > swallowed by cell membrane via endoyctosis Will eventually lead to uncoating

Answer 28

Endocytosis

Question 29

Will occur differently in RNA and DNA viruses

Answer 29

Animal virus: synthesis & assembly

Question 30

Release/ exit will depend on if the virus has an envelope or not Virus release is usually lethal to host cell

Answer 30

Animal virus: exit

Question 31

Results in enveloped. Only occurs in animals Cells without walls

Answer 31

Budding

Question 32

Results in naked viruses Lack of plasma membrane envelope

Answer 32

Lysis

Question 33

Carries a virus asymptomatically

Answer 33

Latent virus

Question 34

Viral DNA is incorporated into host DNA Temperate virus

Answer 34

Provirus

Question 35

Genome: ds DNA, Naked, small, icosahedral Tissue tropism: narrow, epithelial & mucous membrane 1st virus that taught us cancer can be cause by an infectious agent

Answer 35

HPV

Question 36

1. Attach to receptors on epithelial cells, actively dividing 2. Endocytosis, uncoated is cytoplasm & nucleus and released in host nucleus 3. Host cell makes copies of viral chromosome & makes protein for capsid 4. Protein that makes capsid return to nucleus to assemble around viral chromosome 5. Visions released when epithelial cells shed

Answer 36

HPV life cycle

Question 37

Genome: 8 segments of -ssRNA w/a prepackaged RNA to RNA polymerase Enveloped Amorphous

Answer 37

Characteristics of Influenza virus

Question 38

Occurs when a coinfection of two different strains of the same virus to diced a hybrid strain

Answer 38

Antigenic shift

Question 39

1. Hemaglutininon attaches to receptors on respiratory cell 2. Endocytosis &fuse w/lysosome, uncoating- RNA & it’s polymerase enter nucleus 3. Viral genes transcribed & translates, viral genome is copied w/help from viral polymerase 4. Packaging proteins return to nucleus, assemble around genome 5. Visions bud off cell w/help from neurominidase, host cell envelope around virus

Answer 39

Influenza life cycle

Question 40

Retrovirus: +ssRNA Genome is back copied to DNA using reverse transcriptase Enveloped, conical shaped capsid Leaves cell by budding

Answer 40

HIV characteristics

Question 41

1. Attach to T lymphocytes on CD4 & CCR5 receptors 2. Enter by membrane fusion, uncoating in the cytoplasm, genome is reverse transcribed. 3. Back copies DNA enters host nucleus & integrates into host chromosome, replicated DNA (provirus) viral mRNA is transcribed and translated 4. Viral spikes in cell membrane, proteins assemble around genome near cell membrane 5. Budding or syncytium

Answer 41

HIV life cycle