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Chapter 9 microb
terms and need to know about chapter 9
| Question | Answer |
|---|---|
| mutations are | inherited changes in the base sequence of DNA. |
| Wild Type or Wild strain is | the natural form of the genome. |
| mutant strain is | the changed form of the genome. |
| Genetic exchange or recombination is | Piece of DNA from one cell enters and is incorporated;[pp;[ to another cell. |
| Non-selectable mutation | doesn't give any advantage to the cell, i.e. color change |
| Selectable mutation | confers an advantage under certain environmental conditions |
| Replica planting | Use sterile velvet pad, press against new plates, then press against new plate, the pattern of calories will be identical to masterplate. |
| auxotroph | A mutant microorganism that has a nutritional requirement that is absent in the parent |
| prototroph | the wild type parent; requires no special growth factor. |
| mutagen | physical or chemical agent that causes mutations |
| spontaneious mutations | occur naturally are usually the result of an error in DNA replication |
| induced mutations | are due to directed chemical or physical agents called mutagen |
| 1)point mutation | only one to a few base pairs of the DNA are disrupted. This can occur by substitution, insertions, or deletions. The phenotype is changed only when the amino acid sequence change. |
| a)silent mutations | usually occur in the third base of the the codon. a change still makes the same protein. |
| b)missence mutations | produce a different but functional protein. May result in a change in physiology like temp sensitivity. |
| c)nonsense mutations | no protein or an incomplete protein produced |
| d) frameshift mutations | due to a deletion or insertion that changes the reading frame triples radically. may be corrected further along the DNA with another insertion. |
| e)back mutations or reversions | the mutated base is changed back to its original form, or an alternative enzyme pathway is used to make a product. |
| f)supressor mutations | new mutations that compensate for the initial mutations and restore the physiology, partially or completely |
| Large number 3 of base pairs mutated | this usually occurs as mistakes in genetic recombination |
| insertions | that totally inactivated one or more genes; usually reversible |
| translocations | a large chunk of DNA is moved to a new location on chromosome |
| inversion | a piece of DNA breaks off and reattaches to the chromosome upside down |
| Induced mutations | Mutations that originate external to the cell, possibly caused artificially by radiation or chemicals, usually for experimental purposes |
| know table 9.4 p.273 | :) |
| The Ames test | This tests for the mutagenity of chemicals. Many will be carcinogenic in mammals. If this can mutate bacterial DNA. It measures the rate of back-mutations in auxotrophs, due to point mutations. An auxotroph is inoculated to agar lacking its growth require |
| ames test | test for mutagenicity used as a screen for carcinogen potential using auxotrophs for their point mutations |
| Genetic recombination or exchange | this involves transmission of genetic material from one to another using plasmids. |
| Conjugation | involves cell 2 cell contact. This is direct transfer of plasmids through pili. The plasmid may remain extrachromosomal and self-replicating or may get incorporated into the genome. plasmids produce the protein which stimulated conjugation. So they direct |
| conjugation | the process by which two prokaryotes bind together and one cell transfers DNA to the other cell through a structure called a sex pilus |
| transformation and oncogenesis | involve special genes called oncogenes that can regulate cellular genomes and control the onset of cell division. |
| transduction is | the transfer of bacterial DNA by a bacterlophage |
| general transduction | random fragments of disintegrating host DNA are taken up by the phage during assembly. Virtually any gene from the bacterium can be transmitted through this means. |
| specialized transduction | specific group of host genes are incorporated into a viral DNA/RNA. transferred into recipient cell on incomplete viral material. Doesn't result in infection with virus (bacterial toxins) |
| transposition transposons or "jumping genes" | These can move around in the genome or move to a plasmid or from a plasmid to a chromosome. They can't be transferred except by conjugation |
| Genomes | complete set of chromosomes & genes in an organism |
| viruses | tiny particles, smaller than bacteria and other pathogens, which must invade living cells in order to reproduce; when they invade, the cells are damaged or destroyed in the process releasing new particles to infect other cells |
| RNA | ribonucleic acid, a natural polymer that is present in all living cells and that plays a role in protein synthesis |
| DNA | the double stranded molecule that contains the genetic code |
| gene regulation | the turning on of off of specific genes depending on the REQUIREMENTS of an organism |
| enzyme induction | enzymes in pathway are normally off and inducer makes repressor inactive and operon is expressed |
| Replication | is a process that creates new DNA. |
| tRNA | transfer RNA; type of RNA that carries amino acids to the ribosom |
| mRNA | messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosom |
| 2 types of positive strand genomes of RNA viruses | 1. genome that comes ready to be translated into proteins 2. genome that can be converted to DNA or a dsRNA genome |
| Replication of dsDNA | viral Dna ENTER NUCLEUS, transcribed,mRNA is translated into structural proteins,viral DNA and proteins are assembled into a mature virus in the nucleus,bc ds the vdna can insert into host dna |
| 1.regulator | composed of the gene that codes fora protein capable of repressing the operon(a repressor) |
| 2.the control locus | promoter singnals the mRNA transcript , operator tells them were 2 begin copying |
| 3.structural locus | made up of three genes(123), each coding for a different enzyme needed to catabolize lactose. |
| B-galactosidase | hydrolyzes the lactose into monosaccharides |
| permease | brings lactose across the cell membrane |
| allosteric | means it has two binding sites one for the operator and another for lactose. |
| copressor | slows the transcription of the operon |
| If lactose is not present | no need for process so repressor binds at the end of operator preventing RNA polymerase from making a messenger RNA of the gene. (turns off/prevents from copying) |
| If lactose is represent and GLUCOSE is absent | lactose binds 2 repressor changing it's shape and causing it to float away from operator. with it gone the operator now signals RNA polymerase a messenger RNA is made of structural genes and then it can go out and make lactase |
| if lactose and glucose are present | nothing changes repressor is in place |
| a repressible operon | an iccummulating protein product feeds back to the genes to turn off its own production |
| Arg operon | repressor=normally attached, when arginine builds up some attaches to the repressor protein which changes shaper.binds to operator shutting down transcription. |
| gene regulation | regulation of which genes are active&non allow the cell to make protein when needed and not at other times. this conserves resources. Done w/ a group of genes(operons) |
Created by:
tifenny
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