Microbiology (Chp 4)

Question 1

virus

Answer 1

obligate intracellular parasites

- not considered alive (cant reproduce on their own, cant produce their own E)

Question 2

bacteriophage

Answer 2

a virus that parasitizes a bacterium by infecting it and reproducing inside it

Question 3

capsid

Answer 3

protein coat surrounding viral nucleic acid

Question 4

bacteriophage life cycles

Answer 4

1. attachment or adsorption
2. penetration or eclipse

from here phage can follow one of two paths (lytic cycle or lysogenic cycle)

Question 5

attachment

Answer 5

aka adsorption

binding to exterior of bacterial cell

Question 6

penetration

Answer 6

aka eclipse

capsid remains on outer surface of bacterium while the genome disappears into the cell

Question 7

lytic cycle of phages

Answer 7

1. • as soon as phage genome enters host cell, host polymerases and or ribosomes begin to transcribe/translate
   • early genes: hydrolase - degrades host enzyme
2. replicate viral genome
3. late genes: lysozyme - destroys bacterial cell wall
   >host bacterium lyses> releases progeny viruses

(timing of lysozyme is important - if too early phage wouldn’t have had time to replicate and assemble)

Question 8

lysogenic cycle of phages

Answer 8

1. phage genome is incorporated into the bacterial genome (phage now referred to as a prophage and bacterium as lysogen)
2. phage is reproduced when bacterial genome is replicated
3. phage is dormant until stressor
   >excises itself from bacterial genome and enters lytic cycle

Question 9

prophage

Answer 9

phage genome that has been incorporated into bacterial genome

Question 10

transduction

Answer 10

foreign DNA is introduced into a cell by a virus or viral vector

Question 11

endocytosis

Answer 11

animal viruses can enter cells through endocytosis - host cell engulfs the virus and internalizes it

Question 12

productive cycle

Answer 12

animal cells only
similar to lytic cycle but doesnt destroy host cell

instead budding - virus aquires a coating of lipid bilayer (envelope) > host cell can’t differentiate btw itself and virus

Question 13

+ RNA viruses

Answer 13

must ENCODE RNA dependent RNA pol (and do not have to carry it)

translation produces:
viral proteins
negative RNA (complimentary strand) - which RNA dep RNA pol can use to make more + RNA

Question 14

• RNA viruses

Answer 14

must CARRY RNA dependent RNA pol (and encode it too)
template for RNA viral mRNA production

need RNA dep RNA pol to produce + RNA before can start producing more - RNA

Question 15

retroviruses

Answer 15

must encode reverse transcriptase (req RNA dependent DNA polymerase)
ex: HIV

Question 16

subviral particles

Answer 16

infectious agents even smaller and simpler than viruses
include:
prions viroids

Question 17

prions

Answer 17

no DNA or RNA
no membranes
no organells
v small 
extremely stable (can w/stand high T, extreme pH, strong salt conc., etc.)

self replicating proteins (don’t follow central dogma)
misfolding version of a protein that already exists > causes others of that protein to become misfolded

Question 18

viroids

Answer 18

short piece of circular, single stranded RNA
don’t encode proteins
act as miRNA or siRNA to block translation

mostly found in plants (except hep D in humans)

Question 19

Robert Hooke Cell theory

Cork

Answer 19

1. all living orgs are composed of one or more cells and their products
2. cells are the monomer for any org
3. new cells arise from pre-existing living cells

Question 20

primary difference between prokaryotes and eukaryotes

Answer 20

prokaryotes do NOT have membrane bound organelles

Question 21

prokaryotes

Answer 21

means before the nucleus

• no membrane bound organelles
• contain all machinery required for life
• bacteria, archea, blue-green algae

Question 22

plasmid

Answer 22

found in prokaryotes
circular piece of double stranded DNA (smaller than genome) that can contain advantageous info
-ex: antibiotic resistance genes

Question 23

bacterial shapes

Answer 23

round - cocci
rod shaped - bacilli
spiral shaped - spirochetes/spirilla

Question 24

cocci

Answer 24

found bacteria

singular: coccus

Question 25

bacilli

Answer 25

rod shaped bacteria | singular: bacillus

Question 26

spirochetes or spirilla

Answer 26

spiral shaped bacteria | singular: spirochete or spirillum

Question 27

bacterial cell wall is composed of ____

Answer 27

peptidoglycan - complex polymer unique to prokaryotes

Question 28

gram staining

Answer 28

method of classifying bacteria based on cell wall structure (degree to which it can be stained)

Question 29

gram positive

Answer 29

``` dark purple (stain strongly) thick peptidoglycan layer outside the cell membrane and no other layers ```

Question 30

gram negative

Answer 30

pink (stain weakly) | thin layer of peptidoglycan in the cell wall and additional out layer containing lipopolysaccharide

Question 31

periplasmic space

Answer 31

intermediate space in gram negative bacteria between cell membrane and the outer layer

Question 32

bacteria capsule

Answer 32

sticky layer of polysaccharide goo surrounding bacterial cell wall that makes them harder to be eradicated by immune system

Question 33

flagella

Answer 33

filaments involved in bacterial motility can be monotrichous - 1 flagella amphitrichous - two flagella peritrichous - multiple flagella

Question 34

mesophile

Answer 34

bacteria that prefer moderate temp

Question 35

thermophile

Answer 35

bacteria that prefer hot temp

Question 36

psychophile

Answer 36

bacteria that prefer cold temp

Question 37

autotrophs

Answer 37

utilize CO2 as carbon source

Question 38

heterotroph

Answer 38

rely on organic nutrients created by other organisms

Question 39

chemotrophs

Answer 39

get E from chemicals

Question 40

phototrophs

Answer 40

get their energy from light

Question 41

auxotroph

Answer 41

bacterium that cant survive on minimal medium bc it cant synthesize a molecule it needs to live ex: arg- = cant synthesize arg

Question 42

obligate aerobes

Answer 42

bacteria that require O

Question 43

anaerobes

Answer 43

do not require O (3) subcategories: 1. facultative anaerobe - will use O when around but don't need it 2. tolerant anaerobes - grow in presence or absence of O but do not use in their metabolism 3. obligate anaerobes - poisoned by O

Question 44

binary fission

Answer 44

asexual reproduction in bacteria

Question 45

conjugation

Answer 45

mechanism for exchanging genetic information in bacteria

Question 46

bacterial mechanisms for acquiring new genetic material

Answer 46

1. transduction - transfer or genomic DNA from one bacterium to another by a lysogenic phage 2. transformation - bacterial cultures can internalize free DNA under certain conditions 3. conjugation - bacteria make bridge between one another to exchange genetic info

Question 47

F (fertility) factor in conjugation

Answer 47

male: have F Factor female: don't have F factor males transfer replicated F Factor to females

Question 48

parasite

Answer 48

causes damage to host cell can be obligate (must be inside host cell to replicate) or facultative (can live and replicate inside or outside of a host cell)

Question 49

viral life cycle steps

Answer 49

1. attachment (aka adsorption) | 2. injection (penetration)