chapter 13

Question 1

virion

Answer 1

single particle

Question 2

viruses

Answer 2

more than one type of virus (HIV)

Question 3

What was the first virus to be discovered?

Answer 3

TMV, tobacco mosaic

Question 4

Characteristics of viruses

Answer 4

-do not divide
-can carry DNA or RNA but not both
-can perform reverse transcription
-cannot carry out metabolic pathways

Question 5

mama virus and mimi virus

Answer 5

giant viruses

Question 6

extracellular state

Answer 6

virion
-have a protein coat called a capsid that surrounds nucleic acid
-

Question 7

nucleocapsid

Answer 7

combination of both capsid and nucleic acid together

Question 8

intracellular state

Answer 8

capsid is removed and the virus exists as nucleic acid
-while in host cell, they only have a genome

Question 9

Why do viruses only infect certain host cells?

Answer 9

due to the affinity of the viral surface and the complementary proteins on the host cell

Question 10

generalists

Answer 10

infect many kinds of cells or many different hosts

Question 11

What is the smallest virion?

Answer 11

bacteriophage MS2

Question 12

Is a virion or bacteria bigger?

Answer 12

bacteria

Question 13

What is the biggest animal virus?

Answer 13

smallpox

Question 14

helical

Answer 14

capsid composed of capsomeres bound together in a circular fashion to form a tube around the nucleic acid

Question 15

polyhedral

Answer 15

roughly spherical capsid

Question 16

complex

Answer 16

many different shapes
rabies

Question 17

What is replication dependent on?

Answer 17

the hosts organelles and enzymes

Question 18

lytic replication

Answer 18

viral replication that results in death and lysis of the hosts
-attachment, entry, synthesis, assembly, release

Question 19

lysogenic replication of bacteriophages

Answer 19

the infected host cell grows and reproduces normally for generations before they lyse

Question 20

What are bacteriophages called in their inactive state?

Answer 20

prophages

Question 21

lysogenic conversion

Answer 21

phages carry genes that alter the phenotype of a bacterium from harmless to pathogenic

Question 22

Animal virus replication

Answer 22

same replication pathway as bacteriophages
results may vary due to the presence of an envelope, lack of cell wall

Question 23

In animal virus replication, where does DNA enter?

Answer 23

the nucleus

Question 24

In animal virus replication, where does RNA replicate?

Answer 24

in the cytoplasm

Question 25

What are the four types of RNA viruses?

Answer 25

ssRNA, retroviruses, dsRNA

Question 26

retroviruses

Answer 26

do not use genomes as mRNA,(HIV), use reverse transcriptase

Question 27

latency

Answer 27

phase where animal viruses that remain dormant in host cells

Question 28

What occurs during the penetration stage of the lytic cycle?

Answer 28

the phage injects its DNA into the host cell

Question 29

Synthesis stage of the lytic cycle

Answer 29

the phage causes the host DNA to break into small pieces and then uses the host to make new copies of its DNA

Question 30

Assembly stage (lytic)

Answer 30

the phage components are assembled into virions

Question 31

Release stage (Lytic)

Answer 31

the virons are released to infect other cells

Question 32

temperate bacteriophages

Answer 32

their DNA forms a circle that can replicate and be transcribed or can proceed to the lysogenic cycle after penetration

Question 33

Lysogenic cycle

Answer 33

the phage DNA integrates within the bacterial chromosome by recombination and the inserted phage DNA is a prophage - when the bacterium reproduces, the prophage is copied

Question 34

induction

Answer 34

prophage is excised through the host chromosomes in a process called induction in the lysogenic cycle and after the prophage can enter the lytic cycle

Question 35

Which of the following proteinaceous subunits make viral capsid?

Answer 35

capsomere

Question 36

The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle?

Answer 36

entry and release