Virus

Question 1

Virus Capsid

Answer 1

Protein sheath around nucleic acids

Question 2

Virus Envelope

Answer 2

in some viruses, formed around capsid with viral proteins and host’s lipids

Question 3

Virion

Answer 3

1 viral cell

Question 4

Viral structure

Answer 4

core of nucleic acid surrounded by protein

Question 5

Classified by nature of Genome. 3 types are

Answer 5

DNA viruses
RNA viruses (most common)
Retroviruses: RNA viruses that use reverse transcriptase (= backwards transcription) to convert its genes to DNA

Question 6

Host Range

Answer 6

suitable cells for a virus

Question 7

DNA viruses characteristics

Answer 7

Most are double-stranded
Replicated in nucleus of eukaryotic host cell
Fewer mutations

Question 8

RNA virus characteristics

Answer 8

Most are single-stranded
Replicated in cytosol of eukaryotic host cell
RNA replication high in mutations constantly changing difficult for host, vaccines, and drugs

Question 9

Retrovirus characteristics

Answer 9

employ reverse transcriptase

Specialized RNA virus

Question 10

Tissue tropism

Answer 10

types of cells within host which can infect by recognizing cell surface proteins on host

Question 11

Virus can reproduce

Answer 11

only in host cell

Question 12

Virus reproduce only in host, why?

Answer 12

Outside, it is metabolically inert virion
Lack enzymes and ribosomes for transcription and translation
Viral genes translated into proteins by host viral proteins assemble more viruses within host

Question 13

Early genes

Answer 13

before replication; viral proteins.

Question 14

Middle genes

Answer 14

replication of viral nucleic acids and production of viral capsid proteins.

Question 15

Late Genes

Answer 15

after replication. proteins for assembly and release

Question 16

3 viral shapes

Answer 16

Helical = rod-shaped (most viruses)
Isometric - spiral
Icosahedral = spherical

Question 17

Some viruses are complex

Answer 17

Poxviruses have multilayered capsid

T-even bacteriophages (ex. T2,T4,T6) have binal symmetry = both icosahedral and helical portions

Question 18

Enveloped viruses are

Answer 18

polymorphic = no distinctive symmetry

Question 19

Bacteriophage

Answer 19

viruses that infect bacteria
Viruses have also been found in archaea
Some very unique with complex symmetry

Question 20

Bacteriophages: Exhibit 2 reproductive cycles

Answer 20

Lytic and lysogenic cycles

Question 21

lytic cycle

Answer 21

utilize host cell’s machinery to replicate viral genome then kill host cell

Question 22

lysogenic cycle

Answer 22

integrates viral genome into host’s genome

Question 23

How are the two cycles termed

Answer 23

Lytic virus are termed virulent

Lysogenic virus are termed temperate

Question 24

lytic cycle process

Answer 24

tail fiber contacts lipoproteins of host bacterial cell wall (attachment or adsorption)
tail contracts and tail tube passes through opening in base plate, piercing bacterial cell wall

Question 25

injection lytic

Answer 25

Contents injected into host cytoplasm

Question 26

synthesis lytic

Answer 26

viral genome and proteins replicated

Question 27

assembly lytic

Answer 27

– viral components put together

Question 28

release lytic

Answer 28

viral exit

Question 29

naked viruses

Answer 29

lyse ( dissolution or destruction) of the host cell to exit

Question 30

Envelope virus

Answer 30

bud off host cell with no harm or produce enzymes which harm/kill host cell

Question 31

Lysogenic cycle process

Answer 31

The integration of a virus into a cellular genome is termed lysogeny.

Question 32

Prophage

Answer 32

viral genome segment integrated into host genome

Question 33

Lysogen

Answer 33

host cell with lysoge

Question 34

phage conversion ( lysogenic)

Answer 34

prophage alters the bacterial phenotype causing harmless bacteria to become harmful with viral gene for toxin lysogenically within host genome

Question 35

Steps of lysogenic cycle

Answer 35

viral genome added into host chromosome  prophage inside lysogen
Propogation = replication of prophage with host genome replication of new host cells
Induction = switch from lysogenic to lytic cycle, prophage exits host chromosome

Question 36

HIV is what kind of virus

Answer 36

retrovirus

Question 37

What cells does HIV attack

Answer 37

CD4+, e3specially T cells
= class of CD4+ white blood cells which initiate cell-mediated immune response

Question 38

HIV lytic cycle

Answer 38

Attachment = viral glycoprotein gp120 attaches to cell surface marker of a CD4 cell and CCR5 receptors (receptors will help HIV across cell membrane of CD4 cell)
Penetration= HIV enters CD4 cell by receptor-mediated endocytosis
Synthesis= reverse transcriptase converts RNA to double-stranded DNA
DNA is incorporated into host genome
Assembly = occurs after period of dormancy
Release = new HIV virions exit by budding

Question 39

Influenza is what kid of virus

Answer 39

RNA virus

Question 40

Emerging virus function how

Answer 40

starts in one host then extends host range

Question 41

Hantavirus characteristics

Answer 41

Causes deadly pneumonia
Natural host is deer mice feces and urine
1993 outbreak in USA

Question 42

Ebola

Answer 42

Causes severe hemorrhagic fever
Host unknown
Mortality 78%
1995 outbreak in Zaire

Question 43

SARS

Answer 43

severe acute respiratory syndrome
Pneumonia-like symptoms
Host is civets (a small, African, carnivorous mammals raised and eaten in Asia)
Mortality 8%
Vaccines currently being developed
2003 worldwide outbreak

Question 44

Prions

Answer 44

proteinaceous infectious particles

Normal prion proteins

Question 45

Viroids

Answer 45

= tiny naked molecules of circular RNA

Question 46

Virus transformation/Transfection

Answer 46

genetic alteration of a cell’s genome by the introduction of foreign DNA

Question 47

Gene transfer therapy

Answer 47

has possibility of treating genetic illnesses and fighting cancers
Introduce working copy of gene into virus