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 Intermicrobial Gene Transfer Bacterial cells sharing DNA allowing for new traits that are oftern beneficial to bacterial and harmful to humans Examples o Pilus formation o Capsule formation o Toxin production o Enzyme production o Antibiotic resistance 1 Conjugation Conjugation pilus transfers genes Plasmids are the F cell donor F is the recipient Conjugation pilus brings F and F cell together Donor plasmids get replicated so it does not need to give up their plasmid to the recipient New plasmid gets threaded through pilus New plasmid gets replicated to the new cell creating R Plasmid means resistance plasmid resistance to another F cell antibiotic drugs 2 Transformation Incorporations of DNA from the environment 2 potential outcomes o Unsuccessful Transformation degradation DNA immediately broken down and does not work anymore o Stable Transformation Incorporation of plasmids gets bacteria to uptake this plasmid 3 Transduction Transfer of bacterial DNA by a virus 2 Types o Generalized Random segments of DNA transferred to recipient Penetration Synthesis Assembly New virus is put out into the environment New cell infected with virus from donor o Specialized Specific segments of DNA transferred Infection and Disease Host Microbe Relationships o Mutualism o Commensalism o Parasitism Mutualism When both species directly benefit o Ex Animals provide home for intestinal microbes and microbes give off Vitamin K to animal Commensalism When one species benefits and the other is neither benefitted nor harmed o Ex Dental plaque benefits from living and reproducing in our mouths but we do not benefit from dental plaque Parasitism When one species benefits while the other is harmed o Ex Parasite worms eating away at flesh and blood of animals Normal Indigenous Microflora o Mutualistic or commensal microbes living on the surface of human body o Body systems closest to the outside of the body have more microbes than the internal body systems o The deeper you go into the body the less microbes you find or may even be sterile 1 Resident Microflora Always present on body surfaces from child 2 Transient Microflora Only present under certain conditions that birth to end of life span can last a few months to a year Look at table 13 3 in textbook Flora and examples of each Compare habitats and see how they are different 1 Skin 2 Gastrointestinal Tract oral cavity 3 Large Intestine Rectum Harmless Microbes Become Harmful Pathogens When o Numbers increase more than normal o Microbe enter sterile areas of the body Ex When microflora enter the sterile bladder and form UTI urinary tract infection Canidida Albicanst form of yeast that can cause Vaginitis or Thrush Disease of oral cavity in infants causing white layer of yeast to grow in mouth Clostridium Difficile C Diff Causes overgrowth to occur in the GI tract Antibiotics alter environment of colon o Immunocompromised Failure of immune system Disease can come from your own microflora or sources external to the body Modes of Transmission o Contact o Vehicle o Vector Contact Transmission Physical Contact o Spread from ill human to human contact o Examples STDs or venereal disease Ex gonorrhea genital herpes AIDS HPV Direct fecal oral intestinal infections passed along Ex Day care centers Vertical Transmission Passed from woman to unborn child or child during birth Indirect Contact Transmission Colds coughs sneezes Fomites non living objects No direct contact Ex toys children share Contact Transmission Zoonotic Disease Disease spread from animals from infected tissues or fluids and feces EX Rabies Caused by a virus in skunks raccoons etc From animal saliva Leptospirosis Small rodents spread from bacteria in urine Tularemia Rabbits or rodents rabbit fever Non Communicable Disease where microbe from environments contaminate the fomite Vehicle Transmission 1 Air 2 Water 3 Food Microbe is most commonly shed into vehicle from either human or animal Inanimate objects also spread pathogen EX Stachybotrys A fungi that grows on damp walls that can eventually lead to death of infant or child when infection gets to lungs Airborne Transmission Spread during respiratory infections coughing sneezing droplets Microscopic particles Aerosols travel farther than a meter Droplets Larger particles Waterborne Transmission Ex Water contaminated with fecal material is used or ingested by humans indirect fecal oral Causes gastrointestinal disease o Giardia infections Protozoa drinks water that looks clean from