viral genetics

Question 1

viral genome

Answer 1

may consist of double or single stranded DNA, double or single stranded RNA

Question 2

capsid

Answer 2

protein shell enclosing the viral genome built from capsomeres

Question 3

viral envelope

Answer 3

surrounds the capsids and is derived from the membrane of the host cell; contains host cell membrane proteins and phospholipids

Question 4

bacteriophage

Answer 4

viruses that infect bacteria and have the most complex capsids

Question 5

RNA viral genes

Answer 5

include specialized virus encoded polymerase that use RNA as a template

Question 6

lytic cycle

Answer 6

last stage of infection, where bacterium lyses open and releases phages produced within cell

Question 7

virulent phage

Answer 7

bacteriophage that reproduces only by a lytic cycle

Question 8

lysogenic cycle

Answer 8

replicates the phage genome after the viral genome enters by genetic recombination

Question 9

temperate phage

Answer 9

phage capable of using both lysogenic and lytic cycle for replication

Question 10

prophage

Answer 10

after being integrated into the bacterial chromosome the viral DNA is a prophage that blocks transcription of viral genes

Question 11

enveloped viruses

Answer 11

not all viruses have envelopes; reproductive cycle that allows virus to export and infect other cells without lysing cell

Question 12

retrovirus

Answer 12

RNA animal virus equipped with the enzyme reverse transcriptase; HIV is retrovirus

Question 13

provirus

Answer 13

integrated viral DNA from reverse transcriptase that does not leave the hosts genome

Question 14

vaccines

Answer 14

harmless variants or derivatives of pathogenic microbes that stimulate immune response

Question 15

viral horizontal transmission

Answer 15

a plant is infected from an external source of the virus

Question 16

viral vertical transmission

Answer 16

plant inherits a viral infection from a parent

Question 17

viroid

Answer 17

circular RNA pathogenic molecules; only several hundred nucleotides long, that infect plants

Question 18

prions

Answer 18

infectious proteins which appear to cause a number of degenerative brain diseases

Question 19

prion transmission

Answer 19

misfolded protein that induces the correct protein upon contact to assume the incorrect shape

Question 20

transformation

Answer 20

uptake of naked, foreign DNA from the surrounding environment in bacteria capable of natural transformation or induced

Question 21

transduction

Answer 21

phages carry bacterial genes from one host cell to another after incorrect insertion of bacteria DNA into phage

Question 22

conjugation

Answer 22

direct transfer of genetic material between a bacteria with F factor and another bacteria

Question 23

plasmid

Answer 23

small, circular, self replicating DNA molecule separate from bacterial chromosome

Question 24

episome

Answer 24

temperate viruses; genetic element that can replicate either as part or independently of bacterial chromosome

Question 25

transposable element

Answer 25

unlike plasmid or prophage, always part of chromosomal or plasmid DNA

Question 26

insertion sequence

Answer 26

contains only the single gene transposase which recognizes inverted repeats

Question 27

transposon

Answer 27

includes inverted repeats with transposase gene which sandwiches another or multiple genes

Question 28

bacterial operator

Answer 28

controls the access of RNA polymerase to the genes near the promoter

Question 29

operon

Answer 29

the operator, the promoter, and genes they control

Question 30

bacterial repressor

Answer 30

binds to the operator and blocks attachment of RNA polymerase to the promoter

Question 31

corepressor

Answer 31

small molecule that cooperates with a repressor protein to switch an operon off

Question 32

DNA Polymerase III

Answer 32

synthesizes DNA in leading and lagging strand for bacteria

Question 33

DNA Polymerase I

Answer 33

removes RNA primers and fills in with DNA

Question 34

bacteria chromosomes

Answer 34

most bacteria contain circular chromosomal DNA and one chromosome with few million bp

Question 35

bacterial OR

Answer 35

several thousand different genes and one bidirectional origin of replication

Question 36

bacterial DNA compaction

Answer 36

DNA must be compacted 1,000 fold

Question 37

bacterial primosome

Answer 37

DNA helicase+primase

Question 38

bacterial replisome

Answer 38

2 DNA polymerase holoenzymes+primosome