Genetic Mutations: Types, Causes, and Consequences, Quizzes of Medical Microbiology

Download Genetic Mutations: Types, Causes, and Consequences and more Quizzes Medical Microbiology in PDF only on Docsity! TERM 1 Mutations DEFINITION 1 stable, heritable changes in sequence of bases in DNA can be spontaneous or induced TERM 2 Point Mutation DEFINITION 2 Most common from alternation of single pairs of nucleotides from the addition or deletion of nucleotide pairs in protein-coding genes can affect protein structure in a variety of ways Most common: SILENT, MISSENSE, NONSENSE, FRAMESHIFT TERM 3 Larger(chromosomal) Mutations DEFINITION 3 Less common Insertion, deletion, inversion, duplication, & translocation of nucleotide sequences TERM 4 Spontaneous Mutation DEFINITION 4 Arise w/o exposure to external agents May result from errors in DNA replication --due to base tautomerization resulting in transition & transversion mutations --due to insertion or deletion of nucleotides May result from action of mobile genetic elements such as transposons TERM 5 Induced Mutation DEFINITION 5 Caused by agents that directly damage DNA Base analogs DNA modifying agents Intercalating Agents TERM 6 Base Analogs DEFINITION 6 Structurally similar to normal bases Mistakes occur when they are incorporated into growing polynucleotide chain TERM 7 DNA Modifying Agents DEFINITION 7 Alter a base causing it to mispair TERM 8 Intercalating Agents DEFINITION 8 Distort DNA to include single nucleotide pair insertions & deletions TERM 9 Wild Type DEFINITION 9 Most prevalent form of gene TERM 10 Forward Mutation DEFINITION 10 Wild type --> Mutant form TERM 21 Mutant Detection & Selection DEFINITION 21 Observation of changes in phenotype Replica plating technique: to detect auxotrophic mutants Environmental conditions: select for revertants from auxotrophy to prototrophy TERM 22 Carcinogenicity Testing DEFINITION 22 Most carcinogens are mutagents Test for mutagenicity are used to screen for carcinogenic potential Ames Test TERM 23 Ames Test DEFINITION 23 Reversion rate in presence of suspected carcinogen > reversion rate in absence of suspected carcinogen\ Then, agent is a mutant, and maybe a carcinogen TERM 24 Horizontal Gene Transfer(HGT) in Bacteria & Archaea DEFINITION 24 Transfer of genes from one independent mature organism to another Stable recombinant has characteristics of donor & recipient Important in evolution of many species: expansion of ecological niche, increased virulence TERM 25 HGT Mechanisms DEFINITION 25 Occurs in the 3 mechanisms evolved by bacteria to create recombinants Genes can be transferred to same or different species Transfer of gene donor to recipent Exogenote Endogenote Merozygote TERM 26 Exogenote DEFINITION 26 DNA that is transferred to recipient TERM 27 Endogenote DEFINITION 27 Genome of recipeient TERM 28 Merozygote DEFINITION 28 Recipient cell that is temporarily diploid as result of transfer process TERM 29 Recombination at the Molecular Level DEFINITION 29 3 Types: Homologous Recombination Site Specific Recombination Transpostion TERM 30 Homologous Recombination DEFINITION 30 Most common Involves a reciprocal exchange between pair of DNA molecules with same nucleotide sequence RecA protein carry out -->importanf for DNA repair Double strand break model: most accepted TERM 31 Double Strand Break Model DEFINITION 31 Double Strand break Strand degradation via RecBCD occurs at double-stranded break site to yield single-stranded ends RecA promotes strand invasion & d-loop formation Gap repair synthesis fills in vacant region Branch migration & resolution can produce recombinant or nonrecombinant chromosomes TERM 32 Nonreciprocal Homologous Recombination DEFINITION 32 Incorporation of a single strand of DNA into chromosome, forming a stretch of heteroduplex DNA (1 new, 1 old) Proposed to occur during bacterial transformation TERM 33 Site-Specific Recombination DEFINITION 33 Important in insertion of viral genome into host chromosome Only a small region of homology between inserted genetic material & host chromosome TERM 34 Transposable Elements DEFINITION 34 Transposition: segments of DNA that move about the genome can be integrated into different sites in the chromosome "jumping genes" Insertion sequence: simplest transposable element Composite Transposons: transposable elements which contain genes other than those used to transposition TERM 35 Simple Transposition DEFINITION 35 "Cut & paste" transposition Transposase catalyzed excision Cleavage of new target site & ligation into site