Ch 9 Flashcards by MC J

vertical transmission is a method of

composition of genes to gain prokaryotic genomes

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forms of horizontal transmission

-transformation
-conjugation
-transduction
-transposition

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breakdown of E coli genome

88% protein coding
11% for regulation
0.8% tRNA & rRNA genes
20% of genome acquired from other microbes

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gene pools that each species has

core gene pool
flexible gene pool

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E coli GC?

hmm

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core gene pool definition

genes common to all members of a species; typically informational genes

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flexible gene pool definition

genes NOT common to all members of a species; vary among members

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DNA elements of core gene pool

chromosomes and some plasmids

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encoded features of core gene pool

ribosomes
cell envelope
key metabolic pathways
DNA replication
Nucleotide turnover

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DNA elements of flexible gene pool

genomic islands and islets
bacteriophages
plasmids
integrons
transposons

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encoded features of flexible gene pool

pathogenicity
antibiotic resistance
secretion
symbiosis
degradation
secondary metabolism; restriction modification; transposases/integrases

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transformation definition

uptake of “naked DNA” from the environment

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Conjugation definition

transfer of DNA via cell-to-cell contact

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transduction definition

DNA transfer via a viral intermediate

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transposition definition

transfer of transposons (mobile genetics elements)

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genomic islands definition

transferred genetic elements containing large number of genes of similar function

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which genes do pathogenicity islands contain

virulence genes
antibiotic resistance genes

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bacteria host interactions are found in what kind of genomic island

symbiosis islands

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fitness islands contain

catabolic pathway

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potential fate of DNA acquired via horizontal transmission

degrade DNA; use as food
recombine w chromosome
co-exist

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_____ is a major recombination protein

RecA; scans DNA for, and aligns with homologous regions

in order to uptake DNA, a cell must be

competent

in order to be competent, a cell must accumulate

competence factors

formation of ______ allows gram-positive bacteria to uptake DNA fragments

transformasome complex

quorum sensing mechanism controls

competence; is a cell density dependent phenomenon (prior example: biofilm formation)

for transformation, gram-negative bacteria use

type IV pilus haemophilus neisseria; pilus attaches to external DNA fragment and brings into cell

artificials transformation works by

inducing competence in cells by addition of chemicals, or via electric charge (electroporation)

if threshold level of CF accumulate...

...CFs bind sensor protein; binding initiates sigma factor expression

the transformasome imports

only one DNA strand of the double helix

inside cell, transformed DNA may

recombine with host chromosome

conjugation typically occurs in which species

bacterial, archeal

fertility factor or F factor function

facilitates conjugation; F+ cells contain F factor, known as conjugative or transferable plasmids

Donor cells are ____ and recipient cells are ____ that conjoin via _____

F+ F- sex pilus to transfer plasmid

conjugation-specific genes include

tra genes sex pilus relaxosome: facilitates bridging of cells and transfer of DNA oriT (for transfer) OriV (used when not conjugating)

inside recipient cell, F factor can either

remain as a plasmid or integrate into the chromosome via recombination (yields a cell termed an Hfr cell)

Hfr stands for

high-frequency recombination strain; capable of transferring portions of the chromosome during conjugation

Hfr formation integration occurs at

areas of homology between plasmid and chromosome

Hfr x F- mating means

F- gains chromosomal genes but remains F-

F' (F prime) factor formation occurs when

error in excision of integrated F factor from host chromosome (aberrant excision) -excised F factor contains some host DNA; extra genes expressed as a part of the F' plasmid -acquisition of F' plasmid by a cell can result in partial diploid; acquires extra copy of a chromosomal gene

generalized transduction means that

any gene can transfer between cells

transduction: during viral life cycle, _________ are mistakenly packaged in _______

host DNA fragments; phage particles

TRANSDUCTION: infectious phage contain ______ which infect new host and transfer to DNA

bacterial DNA

specialized transduction

transfer of a few closely linked genes

transposable elements exist only as

forms integrated into DNA

transposable elements are not ______ like plasmids

autonomous

transposition is the process of

mobilizing the transposable elements within or between DNA molecules

transposable elements include

transposase gene & simplest

transposase gene function

catalyses transfer or copying unit from one DNA to another

simplest properties

insertion sequences (IS); have only a transposase and possess inverted repeat sequences

complex transposon composition

insertion sequences + additional genes

conjugative transposons

transfer of transposon to another cell via conjugation