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MCAT Bio > Microbiology (Chp 4) > Flashcards

Microbiology (Chp 4) Flashcards

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1
Q

virus

A

obligate intracellular parasites

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

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2
Q

bacteriophage

A

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

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3
Q

capsid

A

protein coat surrounding viral nucleic acid

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4
Q

bacteriophage life cycles

A
  1. attachment or adsorption
  2. penetration or eclipse

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

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5
Q

attachment

A

aka adsorption

binding to exterior of bacterial cell

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6
Q

penetration

A

aka eclipse

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

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7
Q

lytic cycle of phages

A
    • 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)

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8
Q

lysogenic cycle of phages

A
  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
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9
Q

prophage

A

phage genome that has been incorporated into bacterial genome

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10
Q

transduction

A

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

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11
Q

endocytosis

A

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

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12
Q

productive cycle

A

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

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13
Q

+ RNA viruses

A

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

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14
Q
  • RNA viruses
A

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

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15
Q

retroviruses

A

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

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16
Q

subviral particles

A

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

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17
Q

prions

A 
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

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18
Q

viroids

A

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)

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19
Q

Robert Hooke Cell theory

Cork

A
  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
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20
Q

primary difference between prokaryotes and eukaryotes

A

prokaryotes do NOT have membrane bound organelles

21
Q

prokaryotes

A

means before the nucleus

  • no membrane bound organelles
  • contain all machinery required for life
  • bacteria, archea, blue-green algae
22
Q

plasmid

A

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

23
Q

bacterial shapes

A

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

24
Q

cocci

A

found bacteria

singular: coccus

25
Q

bacilli

A

rod shaped bacteria

singular: bacillus

26
Q

spirochetes or spirilla

A

spiral shaped bacteria

singular: spirochete or spirillum

27
Q

bacterial cell wall is composed of ____

A

peptidoglycan - complex polymer unique to prokaryotes

28
Q

gram staining

A

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

29
Q

gram positive

A 
dark purple (stain strongly)
thick peptidoglycan layer outside the cell membrane and no other layers
30
Q

gram negative

A

pink (stain weakly)

thin layer of peptidoglycan in the cell wall and additional out layer containing lipopolysaccharide

31
Q

periplasmic space

A

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

32
Q

bacteria capsule

A

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

33
Q

flagella

A

filaments involved in bacterial motility

can be
monotrichous - 1 flagella
amphitrichous - two flagella
peritrichous - multiple flagella

34
Q

mesophile

A

bacteria that prefer moderate temp

35
Q

thermophile

A

bacteria that prefer hot temp

36
Q

psychophile

A

bacteria that prefer cold temp

37
Q

autotrophs

A

utilize CO2 as carbon source

38
Q

heterotroph

A

rely on organic nutrients created by other organisms

39
Q

chemotrophs

A

get E from chemicals

40
Q

phototrophs

A

get their energy from light

41
Q

auxotroph

A

bacterium that cant survive on minimal medium bc it cant synthesize a molecule it needs to live

ex: arg- = cant synthesize arg

42
Q

obligate aerobes

A

bacteria that require O

43
Q

anaerobes

A

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

44
Q

binary fission

A

asexual reproduction in bacteria

45
Q

conjugation

A

mechanism for exchanging genetic information in bacteria

46
Q

bacterial mechanisms for acquiring new genetic material

A
  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
47
Q

F (fertility) factor in conjugation

A

male: have F Factor
female: don’t have F factor

males transfer replicated F Factor to females

48
Q

parasite

A

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)

49
Q

viral life cycle steps

A
  1. attachment (aka adsorption)

2. injection (penetration)

MCAT Bio (6 decks)

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