Term
| 2 ways bacteria adjust to new circumstances |
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Definition
| regulation of gene expression and genetic change |
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Term
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Definition
| sequence of nucleotides in the dna, observable characteristics |
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Term
| why do genetic changes have a significant impact in bacteria |
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Definition
| because they are haploid - contain only a single copy of genes (no back-up), often alters phenotype |
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Term
| which can be altered by environment phenotype or genotype |
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Definition
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Term
| 2 mechanisms to cause genetic change in bacteria |
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Definition
mutation
horizontal gene transfer |
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Term
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Definition
| changes in existing nucleotide sequence of a cell's dna, which is then passed on to progeny |
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Term
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Definition
| acquisition of genes from another organism which is then passed on to progeny |
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Term
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Definition
| a mutant that requires a growth factor |
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Term
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Definition
| a mutant that does not require growth factors |
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Term
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Definition
| genetic mutations that result from normal cell processes (occurs randomly, but at characteristic rates) |
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Term
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Definition
| probability a mutation will occur in a given gene per cell division (typically 10^-4-10^-12...or 1 in 10,000 -> 1 in a trillion) |
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Term
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Definition
| mutations passed to a cell's progeny, but then change back to non mutant state |
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Term
| why are 2+ antimicrobial drugs given at once |
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Definition
| to prevent pathogens from developing resistance, chances of single cell becoming resistant to both = the product of both mutation rates |
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Term
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Definition
| incorrect nucleotide is incorporated to DNA, if only one base pair is "point mutation" |
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Term
| base substitution leads to 3 outcomes |
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Definition
silent - does not alter function of protein
missense - (mistake) codes for wrong amino acids, protein doesn't function fully (leaky)
nonsense - codes for premature codon, shorter and often nonfunctional protein |
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Term
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Definition
| jumping genes - segments of DNA that can move from one location to another in a cells genome |
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Term
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Definition
| genetic changes that occur due to an influence outside of a cell (agent that causes change = mutagen) |
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Term
| why can't transposon replicate on its own |
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Definition
| lacks origin of replication |
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Term
| transposons generally do what |
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Definition
| inactivate the gene it inserts to |
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Term
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Definition
| ultraviolet light causes covalent bonds to form between thymine molecules, distorts dna molecule, replication & transcription stall at the distortion |
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Term
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Definition
| DNA polymerase can backup and excise a nucleotide that is not correctly hydrogen bonded, and incorporate the correct base |
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Term
| in a mismatch repair, how does the cell know which strand to remove |
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Definition
| soon after DNA strand is synthesized, an enzyme adds methyl groups to certain nucleotides |
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Term
| how to repair thymine dimers (2) |
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Definition
photoreactivation/light repair- enzyme uses energy of visible light to break the covalent bonds (only in prokaryotes)
excision repair (dark repair) - enzyme recognizes distortions and makes cuts on both sides of damage to remove it |
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Term
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Definition
| last ditch mechanism for extensively damaged DNA, includes DNA polymerase that synthesizes w/o proofreading, causes errors (SOS mutagenesis) |
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Term
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Definition
| master plate pressed to velvet, then velvet pressed to nutrient agar & glucose salts agar...prototrophs grow on both types, auxotrophs grow only on nutrient agar |
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Term
| penicillin enrichment of mutants |
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Definition
| used before replica plating, increases proportion of auxotrophs by incubating in glucose-salts broth & penicillin. penicillin kills growing prototrophs, so auxotrophs survive. then penicillinase kills penicillin |
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Term
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Definition
| cancer causing agents, most are mutagens |
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Term
| Ames test for carcinogens |
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Definition
| tests for reversion rate of histidine requiring auxotroph, if chemical is mutagenic reversion rate will increase relative to control |
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Term
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Definition
| cells resulting from donor/recipient horizontal gene transfer - have properties of each of the original strains |
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Term
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Definition
| naked DNA taken up into cell, from burst cells or cells that secreted DNA |
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Term
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Definition
| has an origin of replication, can duplicate dna and pass to daughter cells |
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Term
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Definition
| donor DNA is similar in nucleotide sequence to a region in recipient cell's genome |
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Term
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Definition
| physiological state that allows the cell to take up DNA, requires a high concentration of bacteria (sense via quorum sensing) |
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Term
| bacillus subtilis triggered to become competent by what |
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Definition
| when nitrogen or carbon becomes scarce |
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Term
| what fraction of population becomes competent under ideal conditions |
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Definition
| only a fraction, thus seemingly identical cells in the same environment can differ in physiological properties |
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Term
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Definition
| double stranded DNA binds to receptors on cell, only one strand enters, nucleases degrade other. only one daughter cell will inherit donor dna |
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Term
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Definition
| bacteriophages (phages) transfer bacterial genes |
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Term
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Definition
| bacterial viruses - DNA or RNA surrounded by protein coat , attaches to a cell and injects its nucleic acid, which produces more phages |
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Term
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Definition
| rare error that occurs during construction of phage particles, fragment of bacterial dna enters protein coat of phage (instead of only phage/viral dna), called transducing particle |
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Term
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Definition
| result of the general transduction (error) carries no phage DNA, instead injects bacterial dna - which can then integrate into host chromosome by homologous recombination |
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Term
| what produces transducing particle |
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Definition
| error during phage particle construction (instead of bacterial viruses/phages replicating in protein coat, bacterial dna does) |
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Term
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Definition
| complex process requiring contact between donor and cells, can occur in both gram + and - |
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Term
| which process of conjugation studied in book |
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Definition
| gram neg - F plasmid of E. coli |
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Term
| how are plasmids most frequently transferred to other cells |
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Definition
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Term
| can plasmids be replicated inside cells independent of chromosomal replication? |
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Definition
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Term
| steps in plasmid transfer via conjugation (4) |
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Definition
making contact
initiating transfer
transferring DNA
transfer complete |
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Term
| conjugation - making contact |
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Definition
| making contact - F pilus of donor (F+ cell) binds to recipient cell (F- cell) |
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Term
| conjugation - initiating transfer |
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Definition
| initiating transfer - F pilus retracts, pulling cells together, plasmid of donor is cut at origin of transfer (single strand) |
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Term
| conjugation - transferring dna |
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Definition
transfering dna - single strand enters recipient, is replicated as it enters
(remaining donor strand also replicated) |
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Term
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Definition
| both cells now F+, both can synthesize the F pilus (and do it again) |
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Term
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Definition
| less common than plasmid transfer, happens with HFr cells (high frequency of recombination) |
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Term
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Definition
| where F plasmid has integrated into chromosome (in plasmid conjugation only plasmids transfers, bacterial chromosomes unaaffected) |
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Term
| what is different between chromosome transfer and plasmid transfers |
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Definition
| during transfer, whole chromosome (including integrated F plasmid part) tries to transfer, but is interrupted takes too long |
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Term
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Definition
| code for antibiotic resistance (as opposed to plain plasmids - code for nonessential information) |
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Term
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Definition
| genes which vary considerably (mobilome) |
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Term
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Definition
| portion of a strains genes that are found in all strains (75% for E.coli), rest can move from one DNA to another are mobile |
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Term
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Definition
| large DNA segments in a cell's genome taht originated in other species |
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Term
| low- copy number plasmids |
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Definition
| occur in only one or a few copies of a cell (as opposed to high) |
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Term
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Definition
| carry all the genetic information needed for transfer including an origin of transfer |
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Term
| can plasmids travel between unrelated species |
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Definition
| yes - even between gram positive and gram negative |
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Term
| how do plasmids enable many organisms becoming resistant to many microbials |
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Definition
| they can give simulataneous resistance to many antimicrobials and many have a broad host range |
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Term
| transposons do 2 major things |
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Definition
| cause mutations, provide a mechanisms for transferring genes |
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Term
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Definition
| simplest transposon that encodes only the enzyme responsible for transposition transposase |
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Term
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Definition
| one or more genes blanked by an insertion sequence, causes nonhomologous recombination (does not require similar nucleotide sequence) |
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Term
| how is vancomycin resistance transferred from Enterococcus faecalis to Staphylococcus aureus |
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Definition
| E. faecalis transferred its transposon-containing plasmid to S. aureus by conjugation, which as later destroyed, but before so the transposon jumped to the plasmid already in S. aureus |
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Term
| recombinant DNA techniques |
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Definition
| researchers isolate genes from one organism manipulate the purified DNA in vitro, and then transfer them to another organism |
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Term
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Definition
| process of deliberately altering an organisms genetic information using in vitro techniques |
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Term
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Definition
| enzyme recognizes specific nucleotide sequence and then cuts the DNA at the site |
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Term
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Definition
| is used to form covalent bonds between adjacent (fragments) of nucleotides |
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Term
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Definition
| separates DNA fragments by size, long fragments move slower |
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Term
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Definition
| Negative - so moves from negative to Positive |
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Term
| what is used to dye DNA before electrophoresis |
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Definition
| ethidium bromide - binds DNA and flouresces under UV light |
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Term
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Definition
| a fragment of DNA (obtained using a restriction enzyme) is inserted into a vector and then transferred to another cell where it replicates |
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Term
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Definition
| DNA molecule used as the carrier for the cloned DNA |
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Term
| what does DNA cloning require |
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Definition
| a plasmid or other independently replicating DNA molecule |
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Term
| human insulin obtained how now, before |
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Definition
| one of first pharmaceutical proteins to be produced through genetic engineering, used to be extracted from pig & cattle pancreas |
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Term
| genetically engineered vaccines |
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Definition
| genes coding for proteins that induce protection/immunity against a disease, are cloned into yeast or bacteria |
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Term
| examples of vaccines produced by bacteria/yeast |
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Definition
| hepatitis B, cervical cancer, foot & mouth disease of animals |
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Term
| genetically engineered organism used in cheese production |
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Definition
| rennin (chymosin) - causes milk to coagulate and change it beneficially, (originally from stomach of calves) |
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Term
| other examples of genetic engineering |
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Definition
| bovine somatotropin - growth hormone that increases milk production in dairy cows, restriction enzymes |
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Term
| why are human genes cloned into bacteria to make them easier to study |
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Definition
| human cell has 25k genes, E.coli only 4.5k - easier to isolate the DNA and the gene product |
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Term
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Definition
| multicellular organisms that (plant or animal) that harbor a cloned gene |
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Term
| original basic research on transgenic plants |
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Definition
| Ti plasmid of Agrobacterium tumefaciens, which can be used as a vector to deliver desirable genes to plant cells |
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Term
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Definition
| produced by Bacillus thuringiensis, toxic only to insects & their larvae. producd by GE corn, cotton, potatoes |
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Term
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Definition
| soybeans, cotton, corn engineered to be resistant to glyphosphate (round up) |
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Term
| plants with improved nutritional value |
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Definition
| genes coding for beta carotene & iron introduced to rice..much of world's population is deficient in these nutrients |
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Term
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Definition
| collection of clones that together are the entire genome. |
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Term
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Definition
| restrition enzymes cut original DNA into fragments, vector molecules cut with same enzyme. vectors and original fragments mixed making recombinant molecules. introduced to E. coli. each E. coli cell then has one fragment of the genome |
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Term
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Definition
| process of determining the nucleotide sequence in a DNA molecule |
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Term
| polymerase chain reaction enables what |
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Definition
| creation of more than a billion copies of a given region of DNA in a matter of hours |
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Term
| what are concerns regarding DNA technologies? |
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Definition
| concern over bio terrorism, confidentiality, unintended effects (Bt toxin killing monarch butterflies) or spreading unintentionally (weeds gaining Roundup resistance) |
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Term
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Definition
| disease diagnosis, sample obtained, and treated to release the dna in cells and then to amplify target DNA unique to the suspected organism |
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Term
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Definition
| diagnosing gonorrhea - Neisseria gonorrhoeae, HIV nucleotide sequences |
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Term
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Definition
| double stranded DNA, Taq polymerase heat stable DNA polymerase (from Thermus aquaticus), primers which allow choice of where synthesis starts, deoxynucleotides (dATP, dGTP, dCTP, dTTP) |
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Term
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Definition
| sample heated to denature DNA (95C), temperature lowered (about 50C) primers anneal to complimentary sequences, temp raised to 70C - Taq DNA polymerase optimal temp, which synthesizes DNA |
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Term
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Definition
| exponential each new strand replicates |
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Term
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Definition
| Taq polymerase is heat stable, above temp needed to denature DNA (95C) - otherwise would need to add more each time |
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Term
| key ingredient in sequencing reaction |
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Definition
| dideoxynucleotide - lacks 3' OH and functions as a chain terminator |
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Term
| differences between prok & euk ribosomes |
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Definition
| prok smaller (70S vs 80s), proks 3 strans vs 4 strands of RNA in euks, proks only bound form, euks both bound/unbound, euks have chloroplasts/mitochondria with 70S ribosomes so euks actually have both, Euks have 8 kinds of protein, 5 kinds of RNA, proks have 50 kinds of protein, 3 kinds of RNA |
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Term
| how to make bacteria glow |
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Definition
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Term
| what is gene that makes glow & where from |
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Definition
| Green Fluorescent Protein (GFP) from jellyfish A. victoria |
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Term
| what is used to get the GFP gene into the E. coli |
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Definition
| a vector - here genetically engineered pGLO plasmid, and using arabinose as a genetic switch to regulate expression of the gene |
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Term
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Definition
| cells activate genes that are only useful when expressed by a critical mass (ex. cooperative activities of biofilm formation) |
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Term
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Definition
| cells synthesize one or more "signalling molecules", concentration of these molecules signals level of bacterial concentration |
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Term
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Definition
| use of antibiotic to selectively grow mutant daughter cells (which are antibiotic resistant) |
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Term
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Definition
| isolate auxotroph from prototroph parent, requires replica plating |
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