BACTERIA & ARCHAEAReading AssignmentRecent Exciting DevelopmentsCharacteristics of DOMAINSRelationships of the three DomainsHorizontal Gene MovementGene Transfer between speciesDIRECT SEQUENCINGCulture of microorganismsBinary cell divisionCell Division Increases Cell NumberDoubling timePopulation GrowthModels of Population GrowthMore on population growthMicrobial Growth in Batch CulturesThe Cultural Growth CycleWays to Graph GrowthMETABOLIC DIVERSITY of Bacteria and ArchaeaSOURCES of CARBONSYMBIOSISProblemVocabularyExam 1 Lecture 7 UIC BioS 101 Nyberg1BACTERIA & ARCHAEAThese small cells have the potential for rapid population growth.Bacterial diseases have been effectively controlled thru public health.Exam 1 Lecture 7UIC BioS 101 Nyberg 2Reading Assignment For lectures 7 and 8 read Chapter 28 up to section 28.4. Poke around web to learn about how diseases spread to uninfected individuals.Exam 1 Lecture 7UIC BioS 101 Nyberg 3Recent Exciting Developments 1) The Domain ARCHAEA was discovered in the last 40 years (at the University of Illinois (UIUC) by Prof. Carl Woese). 2) Direct Sequencing has revealed new species that have never been lab grown. 3) Movement of genes from one species to distant species (horizontal gene transfer).Exam 1 Lecture 7UIC BioS 101 Nyberg 4Characteristics of DOMAINSCharacter Bacteria Archaea EukaryaCircular DNA Yes Yes NODNA histones NO Yes YesOrganelles NO NO YesEusex* NO None known CommonCell wall muramic acid no muramic most no wallTranscription simple complex complexTranslation f-MET Methionine MethionineFrom Table 28.1 in Freeman* Eusex (a term I invented) is union of appx equal cells.Exam 1 Lecture 7UIC BioS 101 Nyberg 5Relationships of the three DomainsBacteria Eukarya ArchaeaSmall Subunit RNA sequenceExam 1 Lecture 7UIC BioS 101 Nyberg 6Horizontal Gene Movement Genes are transmitted from parent to offspring. The continuity over generations is called vertical transmission.  The appearance of a bacterial gene in a mammal suggests that pieces of DNA can move horizontally into the genome of other species.Exam 1 Lecture 7UIC BioS 101 Nyberg 7Gene Transfer between species Many of the innovations of genetic engineering are based on moving genes from one species into another. It should not surprise us that evolution has also done this. When the phylogeny of gene A does not match the phylogeny of most other genes in the species, one may suspect that gene Aentered from another species.Exam 1 Lecture 7UIC BioS 101 Nyberg 8DIRECT SEQUENCING DNA sequences can be amplified from a sample without first culturing the organisms. Many ‘species’ have been discovered that have never been cultured.  Archaea, originally thought to be limited to extreme environments, have proved to be common in soil, but remain difficult to culture.Exam 1 Lecture 7UIC BioS 101 Nyberg 9Culture of microorganisms One of the common ways to grow bacteria is on a nutrient gel in a petri dish. The gel is mostly (98%) water with some nutrients but it behaves like a solid. The ‘daughters’ of the original cell do not move much and the population (colony) becomes visible as a dot (spot) on the gel.Exam 1 Lecture 7UIC BioS 101 Nyberg 10Binary cell division A cell dividing into two cells after a period of growth (increase in mass) is the most common form of reproduction, getting more individuals in the population. When a cell divides into two approximately equal sized daughters it is called binary cell division.Exam 1 Lecture 7UIC BioS 101 Nyberg 11Cell Division Increases Cell NumberTime124Exam 1 Lecture 7UIC BioS 101 Nyberg 12Doubling time The interval between cell divisions is called the doubling time as well as the length of the cell cycle. Smaller cells generally have shorter doubling times. Escherichia coli, a common bacteria, has a doubling time as short as 20 minutes.Exam 1 Lecture 7UIC BioS 101 Nyberg 13Population Growth A constant doubling time leads to a pattern of exponential growth. Exponential growth and geometric growthare two expressions of the same pattern. Exponential growth assumes time is continuous. Geometric models assumes an integer number of time intervals, e.g. years.Exam 1 Lecture 7UIC BioS 101 Nyberg 14Models of Population Growth Discrete or GeometricNt+1= λ•Nt Continuous or ExponentialNt= N0•er•tExam 1 Lecture 7UIC BioS 101 Nyberg 15More on population growth Nt= No•2# of doubling timesis another formula for population growth. A single E. coli cell would have 224hr•3doublings per hour=272= 4.72•1021descents in 24 hours and 9•1042in 48 hrs.  This is not possible because the cells will run out of resources.Exam 1 Lecture 7UIC BioS 101 Nyberg 16Microbial Growth in Batch Cultures The “batch” is an unexploited resource. Cell(s) arrive in an environment with resources. After a lag during which they ‘crank up’ the enzymes needed for growth, they grow at their maximum rate until they exhaust the resources necessary for growth (energy & materials). Cells go into shutdown mode and eventually die (except those that are able to get to a new “batch”).Exam 1 Lecture 7UIC BioS 101 Nyberg 17The Cultural Growth Cycle Lag Exponential Stationary Decline DeathNTimeExam 1 Lecture 7UIC BioS 101 Nyberg 18Ways to Graph Growth If a population is growing exponentially (or geometrically) a graph of the log (or ln) of the population size versus time will be a straight line. ‘Straightness’ is an attribute effectively evaluated by ‘eye’ and also by mathematical procedures. Most graphs of growth present the log of N rather than N.Exam 1 Lecture 7UIC BioS 101 Nyberg 19METABOLIC DIVERSITY of Bacteria and Archaea SOURCES OF ENERGY Light Reduced organic molecules Reduced inorganic molecules SOURCES OF CARBON Inorganic =CO2& CO3-& CH4(Autotrophs) Reduced organic compounds (Heterotrophs)Exam 1 Lecture 7UIC BioS 101 Nyberg 20SOURCES of CARBON Autotrophs (inorganic carbon) CO2 CH4 Heterotrophs (reduced organic compounds produced by autotrophs) Sugar Fat ProteinExam 1 Lecture 7UIC BioS 101 Nyberg 21SYMBIOSIS Many protists, plants and animals have bacteria (and Archaea?) that live inside of them that do much of the metabolic work. Rhizobium, a bacterial symbionts of legumes that is able to fix nitrogen (plant trades carbon for nitrogen).Exam 1 Lecture 7UIC BioS 101 Nyberg