Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Chap 11 - Genetics
Genetics of Bacteria
| Question | Answer |
|---|---|
| a mutation is | a heritable change in a DNA Sequence that can lead to a change in the organisms phenotype |
| the visible change in an organism is a change in (phenotype/genotype), however the genetic change in an organism is a change in (phenotype/genotype) | the visible change in an organism is a change in PHENOTYPE; however the genetic change in an organism is GENOTYPE |
| the wildtype strain refers to | the strain that is typically isolated from nature, it can also refer to a single gene |
| a ______________ is a cell/virus that is derived from the wild type that carries a change in genetic sequence | mutant is a cell/virus that is genetically different from the wild type |
| a mutant (can/cannot) be obtained from a parental strain which have been previously derived from the wild-type | a mutant CAN be derived from a parental strain which was previously derived from the wild type |
| explain why a mutant may not differ from the wild-type in phenotype | the genotype might be different in a mutant. however, the gene might still code for the same protein. Therefore, producing the same phenotype |
| in Microbiology, how his genotype represented | italicized three-lowercase letters and a capital letter for the gene (i.e. hisC) |
| observe these examples: hisC1 and hisC2. in the examples, what do the numbers mean | in the examples hisC1 and hisC2, the numbers refer to the order of isolation in the mutations |
| give an example of a bacterial phenotype for the hisC genotype. | His- or His+ |
| how is phenotype usually represented in bacteria | + or - (example: (protein)+ or (protein)-) |
| (selectable/nonselectable) mutations confer an advantage | SELECTABLE mutation confer an advantage |
| under certain environmental conditions, the later generations will outgrow and replace the parental/wild type strains , is an example of ______________________ | selectable mutations |
| give some examples of selectable mutations | antibiotic resistant bacteria |
| selectable mutations are powerful tools because | mutants are easy to select |
| (selectable/nonselectable) mutations do not confer an advantage even though they may lead to a phenotypic change | NONSELECTABLE mutations do not confer an advantage even though they may lead to a phenotypic change |
| color loss in a pigmented organism would be an example of a (selectable/nonselectable) mutation. | color loss would be a NONSELECTABLE phenotypic change |
| what is the purpose of replica plating | screening for nutritionally defective mutants |
| this process includes 1) transferring colonies from a master plate, 2) seeing which colonies can/cannot grow, and 3) picking and purifying the colonies that do grow | replica plating |
| if a colony is unable to grow on a replica plate, this means that | the colony is lacking a curtain nutrient or has a particular mutation |
| an auxotroph is _______________ | an additional nutritional requirement that is needed for growth...usually this nutrient is needs to be added to the petri dish |
| the parental strain is called a _________________ | prototroph |
| ___________________ mutation is a mutation that occurs without external intervention. Most result from occasional errors by DNA polymerase during replication | Spontaneous mutations |
| a _____________________ mutation is made environmentally and deliberately. | induced mutations |
| a(n) (induced/spontaneous) mutation can result from exposure to natural radiation or chemicals | INDUCED mutations can occur from natural radiation or chemicals |
| what is a point mutation | a mutation that only involves one nucleotide base pair |
| point mutations have the ability to ... | change a single amino acid, lead to an incomplete chain, or might not have any effect at all |
| nonsense, missense, and silent mutations are all the result of _______________________ | silent, missense, and nonsense mutations are all the result of POINT MUTATIONS |
| what is a silent mutation | a point mutation that does not affect the sequence of an amino acid in a polypeptide chain...there for the phenotype is not changed |
| the silent mutation is always a ______________________ codon | third base |
| __________ is a mutation that changes the sequence of an amino acid in a poly peptide chain | missense mutation changes the amino acid in a sequence of a polypeptide chain. |
| how could a missense mutation affect the amino acid | if the amino acid is in a critical location (i.e. active site) then the activity of the protein could be altered. |
| (all/not all) missense mutations can lead to dysfunction | NOT ALL missense mutations lead to disfunction |
| what is a nonsense mutation | nonsense mutation leads to a stop codon too early in the polypeptide |
| what typically happens as a result of a nonsense mutation | the polypeptide is incomplete/truncated and will not have normal activity |
| transition base pair substitution is ________________ | switching a purine for the other purine; or a pyrimidine for the other pyrimidine |
| what is a transversion base pair substitution | switching a purine for a pyrimidine and vice versa. |
| what leads to a frameshift mutation | either the deletion of a base pair or the insertion of a base pair |
| the deletion/insertion of _____________ base pairs leads to another amino acid being deleted/inserted | three |
| generally speaking, what does a frameshift do to the genome | frameshifts usually scramble the entire polypeptide sequence up/downstream |
| insertions/deletions can result in the gain/loss of ________________ to ________________________ of base pairs | hundreds to thousands |
| frameshift mutations often result in ___________________ | frameshift mutations often result in COMPLETE LOSS of gene functions |
| what might cause a frameshift mutation | errors during the genetic recombination |
| large number of base pair insertions may be due to ______________________ (DNA being inserted into other DNA) | transposable elements |
| mutation rates depend on _______________ | the frequency of DNA changes and the efficiency of DNA repair |
| what is a reversion | a point mutation that is typically reversible |
| what is a revertant | a strain in which the original phenotype is restored |
| a __________________ revertant is a mutation at the same site as the original mutation | same-site revertant |
| a _____________ revertant restores the original sequence | true revertant |
| the ______________ revertant is a mutation that is in a different site but restores the DNA wild type | second - site revertant |
| a second - site revertant works only if they have ______________________ compensating for the original effect | suppressor mutations |
| where can second-site mutations occur | somewhere elseo on the same gene, on another gene but restores function in the original gene, on another gene and the other gene starts producing the needed protein. |
| what is the relative frequency in errors during DNA replication in microorganisms | 1/10^6 to 1/10^7 per kilobase |
| the relative error frequency in a single gene is (the same/higher/lower) than the error frequency of DNA | the error frequency for a typical gene is about THE SAME as DNA replication errors |
| (eukaryotes/prokaryotes) have about 10-fold lower error rates than (eukaryotes/prokaryotes) | EUKARYOTES have about 10-fold lower error rates than PROKARYOTES |
| why do RNA viruses have the highest rates of errors | RNA viruses have less proofreading and lack RNA repair mechanisms |
| DNA viruses have (higher/lower) error rates than RNA viruses but (higher/lower) error rates than prokaryotes | DNA viruses have LOWER error rates than RNA viruses but HIGHER error rates than prokaryotes |
| single base errors are more likely to lead to (missense/nonsense) mutations because most substitutions encode for amino acids | single base errors are more likely to results in MISSENSE mutations |
| list the three types of point mutations from most frequent to least frequent | missense mutations > silent mutations > nonsense mutations |
| one can (increase/decrease) the pool of mutations in DNA by treating with mutagenic agents, or under conditions of high stress | mutagenic agents/high stress INCREASES the pool of mutations |
| __________________________ is the physical exchange of DNA between genetic elements | recombination is the physical exchange of DNA between genetic elements |
| what is homologous recombination | a process that results in genetic exchange between homologous (closely related) DNA from two different sources |
| ___________________ drives the "crossing over" seen in classical genetics during meiosis | homologous recombination drives the "crossing over" in classical genetics |
| ________________ is an essential enzyme, identified in all Bacteria, Archaea, and most Eukarya | RecA |
| in homologous recombination, ______________________ nicks one DNA strand of the donor molecule | endonuclease |
| the _________________ separates the nicked strand from the other strand | helicase |
| this protein binds to a single-stranded segment and to RecA | single-strand binding protien |
| starting with endonuclease, name the proteins that assist in homologous recombination in order, briefly describe what they do | endonuclease (nicks one strand), helicase (separates the two strands), and single-strand binding protein (keeps strands separate and bound to RecA) |
| ______________ is when base pairing displaces other strand of recipient DNA | strand invasion |
| strand invasion creates.... | recombination intermediates with heteroduplex regions where each strand stand is from a different chromosome |
| in homologous recombination, how do the participating DNA sequences generated a new genotype | the homologous sequences must be related but distinct (i.e. diploid eukaryotic cell DNA) |
| in bacteria genetic recombination can occur after...... | transformation, transduction, or conjucation |
| how do you detect the exchange of DNA in recombinant cells | look at the phenotype, usually the recombinant cells phenotypically differ from both parents |
| in transformation, transduction, or conjugation, (the entire/only part) of the donor chromosome enters the recipient cell | in genetic recombination ONLY PART of the donor chromosome enters the recipient cell |
| in order for the donor DNA to be lost, recombination must take place in..... | the recipient chromosome |
| what is a merodiploid strain | a bacteria that carries two copies of a particular chromosomal segment |
| in a merodiploid strain, usually one copy is on the _________________ and the other copy is on a ___________________ | chromosome; plasmid (or phage) |
| what is complementation | when a functional wild-type supplied by the plasmid/bacteriophage; there for restoring the wild-type phenotype |
| ________________________: the genetic transfer process by which FREE DNA is incorporated into a recipient cell and brings about genetic change | Transformation |
| what is a competent cell | a cell that can take in free DNA and be transformed when this DNA is genetically determined |
| in naturally transformable bacteria, competence is regulated, __________________________ uptake and process DNA | competence-specific proteins |
| what normally regulates transformation in bacteria | quorum sensing (a regulatory system that controls gene expression based on cell density) |
| high-efficiency natural transformation is (common/rare) in Bacteria | high-efficiency natural transformation is RARE in Bacteria |
| in order to make cells more highly competent ... | specific procedures must be implemented |
| ___________________ : when electricity can be used to force cells to take up DNA | electroporation |
| natural transformation starts with ________________________ that becomes irreversible | reversible DNA binding |
| in competent cells, linear DNA is first bound by ______________________ similar to a pilus | DNA-binding protien |
| when a double stranded DNA fragment is taken in and is added to the chromosome..... | a nuclease degrades one strand, and the other strand is taken in |
| ________________________ binds and protects new (imported) DNA during transformation | competence-specific protiens |
| what protein integrates new DNA into existing DNA during transformation | RecA integrates newly imported DNA during transformation |
| what happens to a double stranded DNA during transformation that becomes a plasmid | the DNA must remain double stranded and circular |
| ___________________: is the transfer of DNA from one cell to another by a bacteriophage | transduction |
| name the two types of transduction | generalized transduction and specialized transduction |
| explain what generalized transduction is | the DNA from any portion of the host genome is packaged inside the virion |
| in ____________________ transduction, the donor genes cannot replicate independently and they will be lost without recombination | generalized transduction |
| what is specialized transduction | DNA from a specific regions of the host chromosome is integrated direction into the virus genome |
| during specialized transduction, when may DNA be integrated | lysogeny or homologous recombination |
| give some examples of bacteria with multiple-antibotic resistance genes | E. coli, Salmonella, Shinga-like toxins (in E. coli), virulence factors in Vibrio cholerae, photosythetic cyanobacteria |
| in generalized transduction (virtually any/only specific) genes can be transferred to the transductant | VIRTUALLY ANY |
| what is a transducing particle | a virion that is full of the hosts DNA |
| transducing particles are (effective/defective) | transducing particles are defective and cannot lead to viral infections |
| what happens to transducing particles during lysis | transducing particles are released along with normal virions |
| (generalized/specialized) transduction is extremely efficient | SPECIALIZED transduction is extremely efficient |
| T phage genome is integrated at a specific cite is an example of (specialized/generalized) transduction | T Phages are examples of Specialized Transduction |
| in what type of transduction is viral replication under the control of bacterial host chromosome | in specialized transduction and lysogeny, the viral replication is under the control of the bacterial host |
| (Not a Question...just information) Upon induction, viral DNA sometimes excises incorrectly and takes adjacent host genes along with it | |
| (not question... just information) There is a limit to the amount of host DNA that can replace Phage DNA, but helper phages can assist | |
| what is phage conversion | the alteration of the phenotype of a host cell by lisogenization |
| (not a question) prophage from normal, nondetective temperate infection becomes immune to further infection by same phage | |
| some bacteria are only virulent if they possess a ________________ - which usually carries a toxin | specific prophage |
| manny natural lysogens have been found, suggesting.... | this is an essential process for survival |
| a GTA is | a gene transfer agent |
| what is a gene transfer agent | a defective bacteriophage that transfers DNA between prokaryotic cells |
| a gene transfer agent results from | prokaryotes hijacking deflective viruses, specifically for the purpose of DNA exchange |
| this item contains small random pieces of host DNA, do not contain genes encoding their own production, and do not produce viral plaques | gene transfer agents |
| why might have gene transfer agents have evolved | as a mechanism for protected gene dispersion |
| _______________________: is the horizontal gene transfer that requires cell-to-cell contact | conjucation (mating) |
| conjucation is (chromosome/plasmid) encoded | conjugation is plasmid encoded (F Plasimd) |
| conjugation occurs between | two closely related or distantly related cells |
| what is the difference between the donor and the recipient cell in conjugation | the donor cell contains the plasmid and the recipient does not contain the plasmid |
| (t/f) during conjugation, only the plasmid may be mobilized | wrong (false), other plasmids or chromosomes may be transferred as well |
| F plasmids contains _____________________ that allows the plasmid to integrate into the host chromosome | transposable elements |
| the __________ gene on the F plasmid encodes transfer functions (i.e. synthesis of sex pilus and a type IV secretion system) | tra gene |
| during conjugation DNA is synthesized via the __________________ | rolling circle replication |
| the F plasmid is an _____________, meaning it can integrate into host chrommosomes | episome |
| the cell processing a nonintegrated F plasmid is called a | F+ |
| cells processing an integrated F Plasmid are called | Hfr (high frequency recombination) cells |
| what are the three distinct abilities that results from a cell having an F plasmid | ability to synthesize and F pilus, mibilization of DNA transfer to another cell, alteration of surface receptors so that a cell can no longer be a conjugation recipient |
Created by:
kandriot
Popular Bacteriology sets