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29 Cards in this Set
- Front
- Back
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mutation |
heritable change in DNA sequence -can generate alleles (alternate forms of genes) -can also give rise to new phenotypes |
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vertical gene transfer |
(eukarya) -sexual reproduction -new combinations of genes when gametes from parents fuse |
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horizontal gene transfer |
transfer from 1 independent organism to another 1. conjugation 2. transduction 3. transformation |
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conjugation |
DNA transfer by direct cell contact -requires pili, plasmids -major mode of spreading antibiotic resistance genes |
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plasmids |
double stranded, circular DNA -extrachromosomal -carry genes that confer advantage -can be transferred by conjugation -are replicons--have their own ori |
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episome |
plasmids that exist with or without integrating into chromosome |
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F (fertility) factor of E. coli |
well0studied example of a conjugative plasmid |
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F factor |
1. Pilus extends 2. pilus retracts 3. plasmid encoded enzyme nicks on strand of F factor -single strand enters recipient -rolling circle replication 4. strands replicate, becoming double stranded |
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Hfr cell |
high frequency of recombination -can transfer integrated F factor and part of chromosome to F- cell |
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Agrobacterium tumefaciens |
-causes crown gall disease -has tumor inducing plasmid -piece of Ti plasmid transferred by conjugation into plant cell -piece integrates into plant genome, plasmid genes cause uncontrolled cell growth -conjugated across domains woah |
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Phages |
have head, sheath and tail fibers -tail fibers bend at sharp angle -icosahedral head -attachment is tail first -in attached virions, head appears empty |
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transduction |
bacterial gene transfer by phages 2 types are virulent and temperate |
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virulent |
type of phage -lytic cycles |
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temperate |
type of phage -lysogenic cycles |
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generalized transduction |
during lytic cycle -any part of bacterial genome transferred -during viral assembly, pieces of degraded host DNA mistakenly packaged into phage |
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specialized transduction |
during lysogenic cycle -specific part of genome transferred -prophage incorrectly excises, takes part of genome with it |
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CRISPR |
clustered regularly interspaced short palindromic repeats -clusters of short DNA sequences found in many bacteria and archaea -when phage attacks, bacteria incorporate sequences or viral DNA into their own genetic material, placing them between the repeats -next time the bacteria encounter that phage, they use the DNA in the clusters to make RNAs that recognize the matching viral sequencing -the RNAs guide the Cas proteins to viral DNA, where the Cas protein cuts the invading DNA |
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spacers |
in CRISPR -pieces of phage DNA |
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Fred Griffith |
discovered gene transfer by transformation |
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Transformation |
uptake of free DNA from the environment |
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competent cell |
cell that can naturally take up DNA |
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Gram + streptococcus and bacillus Gram- Haemophilus and Neisseria |
bacterial genera that are competent |
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artificial transformation |
in the lab with bacteria not naturally competent -critical step in cloning -two techniques |
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calcium chloride and electroporation |
two techniques in artificial transformation |
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calcium chloride |
makes cells more permeable -tech in artificial transformation |
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electroportation |
pulses high voltage, temporary holes, cell wall and plasma membrane -tech used in artificial transformation |
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DNA transformation |
bacterial RecA protein integrates DNA by homologous recombination |
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DNA becomes single stranded |
how is DNA changes when membrane bound proteins bring DNA into the cell |
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nuclease |
makes the DNA single stranded when entering the cell |
