CHAPTER 1 ADDED IN CLASS BUT NOT IN OUTLINE Microorganisms are everywhere Some are pathogens but most are harmless or beneficial They can clog pipes but they are also used for Making medicine and controlling disease In agriculture Nitrogen fixing bacteria converts nitrogen gas from the atmosphere into useable nitrogen to be used by the plant Genetically engineered crops In the food industry for things like beer and chocolate In genetic engineering for insulin growth hormone and crops that are resistant to pests heat and herbicides Keeps us alive by recycling nutrients and producing vitamins in the intestines that we cannot produce Microorganisms can cause disease like HIV common colds STD s food poisoning and Microbiologists study bacteria viruses protozoans fungi algae diatoms and more Streptomyces is a bacterium Penicillium is a fungi The study of organisms too small to be seen with the naked eye the study of microbes the flu The microbes What is microbiology What are microbes Forms of life too small to be seen with the naked eye Ex bacteria fungi algae protists The field of microbiology examines how microbes Some are pathogens Some are beneficial normal flora on or in us The microbes interact with humans Interact with food Some destroy crops corn rust late blight Irish potato famine Some make foods beer bread crops how they can be used BY humans make antibodies vitamins insulin etc The microbes If microbiology is the study of life what is the basis for life characteristics of life Metabolism all chemical reactions occurring in the body a controlled set of chemical reactions that extract energy and nutrients from the environment and transform them into new biological materials Growth an increase in the mass of biological material Reproduction the production of new copies of the organism Genetic variation allowing the possibility of evolution or inherited change within a population through natural selection of the course of multiple generations Response adaptation to the external environment within genetic and physiological constraints Homeostasis maintaining internal environment in a steady state active regulation of their internal environment to maintain relative constancy The microbes What macromolecules major units are needed for life The microbes polypeptides one of most important functions is as enzymes macromolecules that catalyze chemical reactions within the cell Example enzyme RNA polymerase responsible for making RNA from DNA during transcription Most abundant in the cell The microbes Polysaccharides polypeptides membrane embedded in lipid bilayer forming a cell s cytoplasmic plasma separates the external environment from the interior of the cell Proteins embedded will allow things in and out Nucleic acids DNA RNA The microbes comparisons of DNA sequences are used to separate life forms into three large groups known as domains The microbes storehouses of genetic information Up until the 1970s organisms were placed into one of two categories prokaryotes eukaryotes depending whether or not they had membrane bound organelles Prokaryotes have no nuclear membrane and no membrane bound organelles includes archaea Ribosomes are NOT organelles but are necessary for making proteins Eukaryotes have nuclear membranes and mitochondria chloroplasts The microbes In the 1970s DNA sequencing was used to compare sequences of ribosomal RNA genes in different organisms This led to a new scheme of organizing life into three domains bacteria archaea eukarya Viruses are not included because they are not cellular and don t have a ribosomal RNA gene They are not alive until they get into host cells The microbes Each of the three domains has some similarities and some differences to the others What about viruses The microbes The microbes Why study microbes Technically viruses aren t considered to be alive They don t replicate outside of the cell They have little to no biochemical activity outside of a host cell They are inert and nonreactive outside of a host cell Microbiology still studies viruses since they are too small to be seen with the naked eye Even bacteria can have viral infections Fast cheap easy to grow Can produce enzymes and molecules for industrial medical use Have small numbers of genes simpler to study Genetic manipulation of single celled bacteria is easier than with multicellular eukarya Microbial genetics What can studying the genetics of microbes teach us about the evolution of life on Earth early environment on Earth was drastically different than today first organisms were single celled prokaryotic organisms first organisms were anaerobes didn t use oxygen very little oxygen in This environment led to initial synthesis of macromolecules and their use in primitive single celled life the atmosphere surface of planet was a soup of chemicals Microbial genetics Multicellular fossils dating to about 0 5 billion ybp years before present have been found meaning microbes dominated the planet for approximately 3 5 billion years Some microbial fossil records do exist largely in fossilized mats stromatolites discovered in Australia So how did the first microbial life arise Microbial genetics 1950s a grad student named Stanley Miller worked with his mentor Harold Urey to simulate the spark that might have started forming organic molecules from the primordial soup Microbial genetics molecules alone aren t life so how did early organic molecules change into the four macromolecules of cells today Iron Containing surfaces the molecules to their surfaces may have helped provide the right environments by sticking early life would need to have genetic information ability to catalyze biochemical reactions and way of separating the cell interior from the external environment Are there molecules or structures that might satisfy those requirements Microbial genetics Yes Some RNA molecules have the ability to catalyze reactions ribozymes combination of ribonucleic acid and enzymes RNA could serve dual purpose of genetic information storage AND catalyzing reactions Microbial genetics what about separating interior from exterior of cell Lipid layer known as tails are hydrophobic heads are hydrophilic could have formed a crude way of separating interior contents from the external may have been early form of plasma membrane micelle environment Microbial genetics basic idea of how microbial life arose on Earth Early conditions formed RNA and micelles RNA can be genetic or catalytic micelles