Chapter 8 – Microbiology Answers – Flashcards
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| genetics |
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| the study of what genes are, how they carry information, how their information is expressed nd how they are replicated and passd to subsequent generations or other organisms |
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| gene |
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| a segment of DNA that codes for a functional product, usually a protein |
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| genome |
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| all the genetic information in a cell |
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| genotype |
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| genetic composition of an organisms |
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| phenotype |
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| the expression of the genes; also known as the physical characteristics; the proteins of the cell and the properties they confer on the organism |
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| chromosome |
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| structure containing DNA that carries hereditary information |
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| transcription |
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| to RNA |
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| translations |
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| to protein |
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| inheritance |
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| linear (to daughter) or horizontal (to recombinant cell) transfer of information |
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| semiconservative replication |
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| each parental strand forms with a new strand leaving daughters with parental-new as opposed to one with parental-parental and the other with new-new |
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| direction of replication |
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| 5' --> 3' |
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| leading strand |
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| synthesized continuously |
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| lagging strand |
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| synthesized discontinuously |
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| bidirectional nature of replication |
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| replicates on both strands going each way |
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| de novo |
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| from nothing; which DNA synthesis cannot do |
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| DNA gyrase |
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| relaxes supercoiling ahead of the replication fork |
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| DNA ligase |
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| makes covalent bonds to join DNA strands; joins okazaki fragments and new segments |
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| DNA polymerase |
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| synthesized DNA; proofreads and repairs DNA |
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| endonucleases |
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| cut DNA backbone in a strand of DNA; facilitate repair and insertions |
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| exonucleases |
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| cut DNA from an exposed end of DNA; facilitate repair |
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| helicase |
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| unwinds double-stranded DNA |
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| methylase |
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| adds methyl group to selected bases in newly made DNA |
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| photolyase |
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| uses visible light energy to separate UV-induced pyrimidine dimers |
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| primase |
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| makes RNA primers from a DNA template |
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| ribozyme |
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| RNA enzyme that removes introns and splices exons together |
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| RNA polymerase |
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| copies RNA from a DNA template |
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| snRNP |
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| RNA protein complex that removes introns and splices exons together |
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| topoisomerase |
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| relaxes supercoiling ahead of the replication fork; separates DNA circles at the end of DNA replication |
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| transposase |
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| cuts DNA backbone leaving single-stranded 'sticky ends' |
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| promoter |
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| where RNA polymerase binds to to start transcription |
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| terminator |
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| where the RNA stops making a protein |
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| codon |
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| three base segments of mRNA that specify amino acids |
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| nonsense codons |
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| do not code for amino acids and are stop signals for translation |
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| anticodon |
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| the base triplet on tRNA |
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| repression |
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| controls the synthesis of one or several repressible enzymes |
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| induction |
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| in the presence of certain chemicals (inducers) cells synthesize more enzymes |
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| operon |
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| unit of regulation that contains a promoter, regulator and structural genes |
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| repressor |
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| the I gene |
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| promoter |
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| the P gene where RNA polymerase binds |
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| Operator |
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| the O gene where regulatory components react |
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| catabolite repression |
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| when there are two operons being used in a sequence, there is a lag period because it takes time to turn on the second operon; at the promoter site there is a place for CAP whih acts as an activator but need cAMP |
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| mutation |
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| change in the nitrogenous base sequence of DNA |
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| base substitution |
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| when one base pair in DNA is replaced with a different base pair |
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| missense mutation |
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| cause amino acid substitutions |
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| nonsense mutation |
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| create a stop codon |
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| frameshift mutaiton |
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| one of a few base pairs are deleted or added to DNA |
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| mutagen |
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| agents in the environment that cause permanent changes in DNA |
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| spontaneous mutations |
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| occur without the presence of any mutagen |
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| examples of cemical mutagens |
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| nucleoside analogs and nitrous acid |
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| nitrous acid as a mutagen |
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| alters adenine so it no longer pairs with thyamine but instead cytosine |
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| nucleoside analogues as mutagens |
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| pose as nitrogen bases and are incorporated into DNA as adenine and pairs with thyamine; or can look like thyamine and bind with cytosine |
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| ionizing radiation |
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| causes formation of ions that can react with nucleotids and DNA backbone |
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| UV radiation |
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| causes bonding between adjacent thymines called thymine dimers |
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| positive (direct) selection |
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| detects mutant cells because grow or appear different |
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| negative (indirect) selection |
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| detects mutant cells because they don't grow at all |
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| replica plating |
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| method for isolating mutant cells |
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| wild type |
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| authentic nonaltered type |
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| vertical transfer |
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| passed from an organism to its offspring |
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| horizontal transfer |
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| involves a portion of the cells DNA being transferred to a donor recipient |
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| transformation |
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| genes are transferred from one bacterium to another as naked DNA; discovered by Frederick Griffith with mice killing experiment |
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| conjugation |
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| one type of cell (F+) gives its plasmid to F- cell |
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| Hfr |
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| high frequency plasmid; when the conjugated plasmid becomes incorporated into the chromosome |
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| transduction |
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| DNA is passed from one bacterium to another by a bacteriophage; the cells DNA is put into the the virus's capsule and transferred to another cell when the viruses lyse; the bacteral DNA is then incorporated into the recipient DNA |
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| conjugative plasmid |
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| carries gene for sex pili and transfer of the plasmid |
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| dissimilation plasmid |
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| encode enzymes for catabolism of unusual compounds |
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| resistance factors |
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| encode for antibiotic resistance |
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| transposons |
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| small segments of DNA that can move from one region to another region of the same chromosome or to a different chromosome or plasmid; they are considered mutagens; they have inverted repeat sequences on either end |
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| simple transposons |
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| insertion sequences- can insert themselves between two pieces of DNA |
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| complex transposons |
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| can carry any type of chene and are a natural mechanism for moving genes |
