Microbial Genetics Consists of nonliving viruses prokaryotic cells bacteria DNA in cells use Replication Duplication of DNA molecules needed for cell division Gene Expression Uses codes to make proteins mRNA rRNA tRNA The Central Dogma DNA RNA Protein DNA is the permanent copy of the code mRNA is the temporary working copy of the code Transcription DNA to RNA code of DNA is transcribed on RNA molecule Translation RNA to Protein mRNA contains the code used in translation Important Terms Gene DNA that codes for one protein DNA Polymerase Enzyme that replicates DNA RNA Polymerase Enzyme that replicates RNA mRNA messenger RNA Transcribed RNA that contains code used in translation Turn on gene expression When energy compounds in the environment express genes for utilization Turn off gene expression When cell no longer needs to replicate that compound Transcription Control By controlling the polymerase enzyme you can control when mRNA is synthesized Operons Genes that encode enzymes needed for metabolism and transcriptional control Inducible Operon turn operon on Repressible Operon turn operon off Ex Arginine stops transcription of genes arginine binds to repressor that binds to operator Lac Operon Inducible operon that transcribes genes when the cell utilizes the sugar lactose when present Lactose binds to the repressor Mutations Mutation A change in the sequence of DNA Point mutation substitute nucleotide Frameshift mutation add or delete nucleotide Most mutations will kill cells or diminish the proper function Not all mutations effect proteins is the genetic code is redundant Genetic codes are read in sequences of 3 o Ex CGC or ATT Antibiotic Resistance When pathogens become more dangerous or harder to treat Causes of Mutations Spontaneous Mistakes in replication ATG instead of ATC Background radiation normal radiation o Radioactive minerals o UV lights Induced exposure to mutagens higher than normal levels Radiation UV gamma rays X rays Chemicals react with parts of DNA
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