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44 Cards in this Set
- Front
- Back
operon
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group of genes with a promoter and operator sites, and structural genes which code for proteins.
not in prokaryotes |
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repression
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(protein) blocks transcription by binding to an operator. Synthesis stops.
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induction
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The synthesis of enzymes in the presence of an inducer.
In the absence of an inducer, a repressor binds to the operator of an operon, and turns off transcription. When present, an inducer binds to the repressor and inactivates it. |
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mutation
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a change in sequence of bases on DNA (or RNA of RNA viruses)
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mutagen
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something that causes a mutation. not always needed.
genotype not phenotype |
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point mutation
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one base substitution.
one thign changes |
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missense mutation
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amino acid is changed
protein's function wont change much. |
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nonsense mutation
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mutation creates a stop codon
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frameshift mutation
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insertion/deletion of one or few bases.
results in misreading the code. |
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spontaneous mutations
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occur without a known mutagen
vs induced mutation |
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chemical mutagens
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nitrous acid and base analogs cause base-pair changes; benzopyrene causes frameshift mutations
sticks itself into the DNA. |
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ionizing radiation
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x rays and gamma rays cause ion formation which causes break in DNA and errors in DNA replication
cell can't recover after circular dna is broken |
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nonionizing radiation
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UV light causes thymine dimer formation, and faulty DNA synthesis.
covalent cross links. excision repair may occur. |
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endonuclease
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find DNA lesion/distorsion in helix and removie it.
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DNA repair polymerase/ligase
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inserts correct pair after endonuclease
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mutagen rate
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the probability that a gene will mutate when a cell divides.
expressed as 10 to the negative number |
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spontaneous rate
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10^-9
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genetic recombination
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the exchange of genes between 2 DNA molecules to form a new combo of genes on one molecule of DNA
mostly in prokaryote than eukaryote |
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recombinant cell
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DNA is transferred from a donor bacterium to recipient bacterium. the recipient becomes this.
basically a new organism. |
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transformation
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naked DNA Goes from cell to cell
discovered by Griffith in 1928 when he was working with 2 strains of Streptococcus pneumoniae |
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conjugation
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via cell to cell contact
requires sex pilus male produces the pilus and finds a female and transfers a plasmid |
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transduction
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via a virus
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DNA transfers between bacteria in what ways?
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transformation
conjugation transduction |
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plasmids
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small DS circles of DNA in cytoplasm. 1-5% size of the chromosome
not essential for cell survival source of genetic variability not in eukaryotic, prokaryotes can have more than one plasmid |
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type of plasmids
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dissimilation
virulence f factors resistance factors (r factors) |
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dissimilation plasmids
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code for enzymes that degrade unusual compounds
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virulence determinants
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code for virulence determinants, like exotoxins
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F factors
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carry genes for sex pili and for transfer of plasmid to another cell
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resistance factors (R factors)
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code for proteins to make cell resistant to antibiotics
jas am RTF region and r determinant |
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F+
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ability to produce the pilus. male with F factor.
female is F- |
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Hfr
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F factor is part of the chromosome of the pilus. in a male
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F factor
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cluster of genes transferred from F+ to F-
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RTF region
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resistance transfer factor. includes genes for plasmid replication and transfer
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r determinant
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resistance genes, penicillinase.
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transposons
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transposable genetic elements. jumping genes.
they move from chromosome --> plasmid, plasmid --> plasmid, plasmid --> chromosome, chromosome -- chromosoem palindromic |
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transposase
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cuts out transposable elements. and insert it somewhere else
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transposition
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cut a gene out and copy it, paste it somewhere else
an IS or a complex transposon is sipped out and inserted in another location |
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complex transposon
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carries other gene between 2 insertion sequences. toxin genes/antibiotic resistance
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significances of recombination
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increase in genetic diversity/change
allows for adaptation of new environments *causes partial or full duplication of genetic material (genetic increase) |
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genetic change in microorganisms contributes to
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antibiotic resistance
host tropism (change in host species) immune invasion (antigenic change) increased pathogenicity (ability to cause disease) |
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tuberculosis
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caused by mycobacterium tuberculosis
gram + rod, aerobe, acid fast has mycolic acids in cell envelope, cell is resistant to drying and dessication. grows very slowly |
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tubercle
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granuloma of macrophages, neutrophils, bacteria, and tissue cells in the lung
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miliary tuberculosis
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bacteria cells rupture
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consumption
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weight loss because of tuberculosis
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