chapter 14 notes

stable, heritable changes in DNA base sequences

alternatve form of a gene

process in which one or more nucleic acids are rearranged or combined to produce a new nucleotide sequence

occur without exposure to external agents

base tautomerization resulting in transition and transversion mutations

somebacteria can select particular mutations to better adapt to the environment

random generation of multiple mutations, survivors are only those cells with favorable mutations

structurally similar to normal bases that make mistakes when added to polynucleotide chains

alter a base causing it to mispair

distort DNA to induce single nucleotide pair insertions and deletions

forms thymine dimers so the DNA no longer serves as a template

going from a wild type to a mutant form

mutant phenotype goes to a wild type mutation

occurs when the second mutation is at a different site htan the original mutation

mutations that affect protein structure

change nucleoside sequence of codon - but not the encoded amino acid

a single base substitution that changes codon for one amino acid into codon for another amino acid

converts a sense codon to a stop codon

results from insertion or deletion of one or two bases pairs in the coding region of the gene

expressed only under certain environmental conditions

unable to make an essential macromolecule

mutation in the operator site and produce altered operator sequences not recognized by the repressor

 protein synthesis is interrupted

used to detect auxotrophic mutants

used to test for carcinogenicity.one plate without test mutagen and one with, check for mutation rate

correction of errors in base pairing made during replication

corrects damage that causes distortions in double helix

• nucleoside excision repair
• excision repair
• bot remove damaged DNA stract using an intact complementary strand as template

directly repairs thymine dimers

catalyst that separates thymine dimers

catalyst for direct repair of alkylated bases

mismatch correction enzyme scan newly synthsized dna for mismatched pairs and then they are removed and replaced by DNA polymerase and ligase

used by e.coli mistmatch repair system to distinguish old dna strands from new strands (new ones aren't methylated)

repairs dna with damage in both strands, uses an undamaged dna molecule

recA

used to repair excessive damage that halts replications and involves recA protein

process in which one ore more nucleic acids are rearranged or combined to produce a new nucleotide sequence

crossing over

vertical gene transfer

dna that is transferred to recipient

genome of recipient

recipient cell that is temporatily diploid as result of transfer process

• homologous recombination
• site specific recombination
• transposition

incorporation of a single strand of DNA into the chromosome forms a stretch of heteroduplex DNA

viruses

• segments of DNA that move about the genome in a process called transposition
• jumping genes

insertion sequences

transposable elements which contain genes other than those used for transposition

small, autonomously replicating DNA molecules that can exist independently or, integrate reversibly into the host chromosome

DNA molecule that can integrate reversibly into the host chormosome

can transfer copies of themselves to other bacteria during conjugation

• direct cell to cell contact
• type 4 secretino system

a copy of the f factor is transferred to the recipient and does not integrate into the host chromosome

F' conjugation

uptake of naked DNA by a competent cell followed by incorporation of the DNA into the recipient cell's genome

the transfer of bacterial genes by viruses

viral process in which the host cell is destroyed or the viral DNA can integrate into the host genome, becoming a latent prophage

• any part of the bacterial genome can be trasnferred
• occurs during the lytic cyle
• host DNA fragments mistakenly packaged into phage head

temperate phages have establised lysogeny

locating genes on an organism's chromosome