Medical Microbiology

TheGeneticVariabilityofBacteria 181

Table3. 3 Continued:GlossaryofImportantTerminology...

Recombination,

Illegitimate

recombination

InsertionoftransposableDNA

Site-specific

recombination

IntegrationorexcisionofaDNAsequencebymeansof

homologousrecombinationinaspecificDNAsegmentcom-

prisingonlyasmallnumberofnucleotides

Replication Reproduction,duplicationofDNA

Replicon DNAmoleculethatreplicatesautonomously

Restriction

endonucleases

EnzymesthatrecognizeandcleavespecificDNAnucleotide

sequences

Semiconservative

replication

DNAduplicationmechanisminwhichoneoldstrandiscon-

servedineachofthetwonewdoublestrands

Conjugal(orsex)

pili

SurfacestructuresessentialtoconjugationinGram-negative

rodbacteria

Sigmafactors ProteinsthattemporarilyassociatewithprokaryoticRNA

polymeraseforspecificpromoterbinding

Supercoil CircularDNAmoleculeadditionallytwistedaboutthehelical

axisintheoppositedirection

Terminator Sequencemarkingtheendofatranscriptionprocess

Transduction Genetransferusingbacteriophagesasvehicles

TransferRNA Specificallybindsanaminoacid(aminoacyltRNA)andtrans-

fersittotheribosome

Transformation Transferofgenesfromadonorintheformof“naked”DNA

Transcription RNAsynthesisatDNA

Translation Ribosomalsynthesisofpolypeptides

Transposase Transpositionenzyme;facilitatesillegitimaterecombination

Transposition TranslocationofamobileDNAelementwithinarepliconor

betweendifferentreplicons

Transposon TransposableDNA;frequentlycontains—inadditiontothe

genesfortransposition—determinantsthatchangethe

phenotypeofabacterialcell

Tripletcode Threenucleotidescodingforoneaminoacid

Vector Vehicleforforeign(passenger)DNA;usuallyaplasmidor

phagegenome

3

Kayser, Medical Microbiology © 2005 Thieme