Bacterial Genetics Flashcards

1
Q

plasmids

A

double-stranded, often circular DNA sequences that are capable of autonomously replicating in a host cell
*NOT part of the core chromosome

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2
Q

genomic thrift

A

majority of bacterial genome is coding for something (selects for rapid growth, ditching genes that slow them down/are not super important)

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3
Q

unique functions that a plasmid may provide a host bacteria

A

-antibiotic resistance
-toxin production
-novel biochemical functions or surface molecules

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4
Q

copy and paste (retro) transposons in bacteria

A

replicative

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5
Q

cut and paste transposons in bacteria

A

conservative (no additional copies)

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6
Q

operons

A

*bacterial genes organized in clusters of related genes
*genes in an operon turn on or off TOGETHER
*a single promoter regulates all of the genes in an operon
*allow efficient use of resources and genomic space (only express the genes when needed)

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7
Q

operon for vancomycin resistance

A

when vancomycin is sensed, the cell switches to making an alternative cross-linker to function in presence of antibiotic
*switches back to off when no vancomycin present

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8
Q

how do bacteria divide / replicate

A

binary fission

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9
Q

wild-type bacteria

A

description of a bacterium that is found MOST ABUNDANTLY in nature

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10
Q

mutant bacteria

A

bacterium that differs genetically from the wild-type; the mutant has a genotype different from the wild-type strain, which may or may not result in a readily observable trait

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11
Q

2 primary mechanisms for generating genetic diversity in bactera

A
  1. vertical transmission - spontaneous and random mutations and selection for bacteria with enhanced properties (slow)
  2. horizontal transmission - gene transfer from other microorganisms (rapid)
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12
Q

4 mechanisms of horizontal gene transfer

A
  1. transformation
  2. transduction
  3. conjugation
  4. transposition
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13
Q

horizontal gene transfer: transformation

A

*uptake by a bacteria of naked DNA
*find DNA in the environment and put it into its own chromosome
*can occur between unrelated bacteria and between domains

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14
Q

examples of transformation in real life

A

*strep. pneumoniae
*haemophilus influenza
*can acquire capsule protein (virulence factor)

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15
Q

horizontal gene transfer: transduction

A

*infection of non-lethal virus carrying bacterial genes
*acquisition of genes from a BACTERIOPHAGE (injection of DNA)

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16
Q

lytic phages

A

phages that cause KILLING of host bacterium

17
Q

lysogenic phage

A

phage that can survive in the bacterium without killing; usually integrated into the bacterial chromosome

18
Q

temperate phage

A

phage capable of undergoing BOTH lytic or lysogenic development

19
Q

virulent phage

A

phage capable of undergoing ONLY lytic development

20
Q

lysogen

A

bacterium harboring a lysogenic phage

21
Q

examples of transduction

A

*many bacterial exotoxins coded for by phages
1. group A strep
2. clostridium Botulinum
3. vibrio Cholerae
4. Corynebacterium diphtheriae
5. Staph aureus
6. E. coli (shiga toxin)

22
Q

restriction systems that limit transduction

A
  1. methylating enzyme protects DNA
  2. endonuclease cuts unmethylated DNA
23
Q

horizontal gene transfer: conjugation

A

*plasmid-mediated exchange of information between bacteria in contact
*can NOT go between gram + and gram -
*not all plasmids are conjugative

24
Q

horizontal gene transfer: transposition

A

*exchange of genetic information via mobile genetic elements
*can be cut and paste or copy and paste
*inverted repeats at either end of the transposons

25
Q

mecA and MRSA

A

*mecA is carried on a mobile genomic element (transposon)
*encodes an ALTERED PENICILLIN BINDING PROTEIN
*causes resistance to beta-lactam antibiotics

26
Q

drug-resistance of Neisseria gonnorhea

A

swaps out the pilin genes to hide from our immune system