Bacteria Intro PDF

Introduction to Bacteria Dr Martin Davey and Dr Chystala Constantinidou (see pre recorded information at bottom right of screen) November 2024 / MD2B3 What are bacteria? Life Domains Bacteria, Archaea and Eukarya Eukarya (Eukaryotes) Eukaryotes have Animals...

Introduction to Bacteria Dr Martin Davey and Dr Chystala Constantinidou (see pre recorded information at bottom right of screen) November 2024 / MD2B3 What are bacteria? Life Domains Bacteria, Archaea and Eukarya Eukarya (Eukaryotes) Eukaryotes have Animals nuclei to enclose DNA Plants apart from the rest of Fungi the cell. Single-cell protists Life domains https:// organismalbio.biosci.gatech.edu/ biodiversity/prokaryotes-bacteria- archaea-2/ What are bacteria? Life Domains Bacteria, Archaea and Eukarya Eukarya (Eukaryotes) can be both multi-cellular and unicellular organisms Animals Eukaryotic cells have Plants nuclei to enclose DNA Fungi apart from the rest of Single-cell protists the cell. Bacteria and Archaea (Prokaryotes) are single-cell organisms Genetic differences Do not have nuclei. Life domains Separate evolutionary lineages https:// Fundamental differences in their chemistry and physiology. organismalbio.biosci.gatech.edu/ biodiversity/prokaryotes-bacteria- archaea-2/ What are bacteria? Prokaryotes tend to be smaller than Eukaryotes Bacterium Do not have any membrane-bound organelles Eukaryotes and Prokaryotes common features DNA Plasma membrane Eukaryote Cytoplasm Ribosomes Why study bacteria? They are everywhere Incredible diversity Impact our Health https://www.frontiersin.org/articles/10.3389/fmicb.2019.00780/full Environment Food Can be engineered https://0-www-nature-com.pugwash.lib.warwick.ac.uk/articles/nm.4517 Describing bacteria Cell shape/arrangement Cell size Colony shape Colony size Colony colour Smell https:// laboratoryinfo.com/ various-shapes- and-arrangements- of-bacterial-cells/ Describing bacteria Cell shape/arrangement Average: Cell size E. coli: 1.1 and 1.5 mm Colony shape B. anthracis: 1.0-1.2mm B. subtilis: 0.25 and Colony size 1.0mm Size can change due to Colony colour environmental conditions Smell  Thiomargarita namibiensis: 100-75 Describing bacteria Cell shape/arrangement Cell size https://microbeonline.com/ characteristics-shape-of- Colony shape pathogenic-bacteria/ Haemophilus influenzae: 0.2- Colony size 0.3mm Colony colour Smell DAVID M. PHILLIPS / SCIENCE PHOTO LIBR ARY Describing bacteria Cell shape/arrangement Cell size Colony shape Colony size Colony colour A bacterial colony is a group of Smell bacteria derived from the same mother cell. This means that it comprises of genetically identical cells. https://www.pathelective.com/micromeded/bacterial-colony-morphologie Describing bacteria Cell shape/arrangement Cell size Colony shape Colony size Colony colour Smell https://www.pathelective.com/micromeded/bacterial-colony-morphologie Describing bacteria Cell shape/arrangement Cell size Colony shape Colony size Colony colour Smell https://microbeonline.com/pathogenic-microbes-characteristics-smell-good-bad/ Describing bacteria Cell shape/arrangement Cell size Colony shape Colony size Colony colour Smell  A Brief History of Microbiology https://www.pacb.com/wp-content/uploads/ Infographic-A-Brief-History-of-Microbiology.pdf National Collection of Type Cultures (NCTC) 100-year Anniversary Bacterial Cell Wall H. Gram, 1884 https://www.technologynetworks.com/immunology/articles/gram-positive-vs-gram- negative-323007 Bacterial Cell Wall https://www.technologynetworks.com/immunology/articles/gram-positive-vs-gram- negative-323007 Growth requirements https://microbenotes.com/classification-of-bacteria-on-the-basis-of-nutr  Growth requirements Oxygen Motile bacteria High O2 Temperature pH https://courses.lumenlearning.com/microbiology/ chapter/oxygen-requirements-for-microbial-growth/ No O2 https://courses.lumenlearning.com/ microbiology/chapter/temperature-and- https://courses.lumenlearning.com/ microbial-growth/ microbiology/chapter/the-effects-of-ph-on- microbial-growth/  Bacterial Growth Binary Fission The Growth Curve https://courses.lumenlearning.com/microbiology/chapter/how-microbes-g Bacterial Growth The Growth Curve Bacterial Growth The Growth Curve Bacterial Growth The Growth Curve Bacterial Growth The Growth Curve CFU: Colony Forming Units OD600: Optical Density @ 600nm  Bacterial Structures Nucleoid Typically single, circular chromosome Not membrane-bound, supercoiled (DNA gyrase and topoisomerase) Packaged with aid of histone-like proteins Plasmids DNA that is not part of the chromosome. Small, typically circular and double-stranded DNA molecules. Multiple copies Often carry genes that confer advantageous traits such as antibiotic resistance https://courses.lumenlearning.com/microbiology/chapter/unique-characteristics-of- prokaryotic-cells/ Bacterial Structures Ribosomes Structures responsible protein synthesis. Inclusions Some bacteria have the ability to store excess nutrients within cytoplasmic structures to use when encountering less favourable environments. Can store glycogen, starch, polymerised inorganic phosphate etc https://courses.lumenlearning.com/microbiology/chapter/unique-characteristics-of- prokaryotic-cells/  Bacterial Structures Endospores Structures to protect the bacterial genome in a dormant state when environmental conditions are unfavourable. Transformation process is called sporulation They can survive without any nutrient source, or water, and exposure to extreme temperatures making them very hard to kill Only some bacteria species can transform to endospores Bacillus anthracis anthrax Clostridium tetani tetanus Clostridium difficile pseudomembranous https://courses.lumenlearning.com/microbiology/chapter/unique-characteristics-of- colitis prokaryotic-cells/ Clostridium perfringens gangrene Clostridium botulinum botulism  Bacterial Structures Fimbria and Pili Structures that allow bacteria to interact with their environment Pili are longer and less numerous than fimbriae Attach to other cells (adhesion) transfer DNA (conjugation) provide movement (twitching) https://courses.lumenlearning.com/microbiology/chapter/unique-characteristics-of- prokaryotic-cells/  Bacterial Structures Flagella Structures used by cells to move in aqueous environments Different numbers and placements Motion in response to environmental signals: chemical gradients (chemotaxis), light (phototaxis), magnetic fields (magnetotaxis) Directional movement is controlled through tumbling and running https://courses.lumenlearning.com/microbiology/chapter/unique-characteristics-of- prokaryotic-cells/  Genomes Varying size Correlation with how much the bacterium depends on its host for survival Pathogens with limited niches tend to have small genomes Environmental bacteria tend to have larger genomes Plasmids Replicate independently & are not essential for normal growth Exchanged between bacteria (horizontal gene transfer) https://courses.lumenlearning.com/microbiology/chapter/structure-and- Can provide new genes beneficial for growth and function-of-cellular-genomes/ survival under special conditions Encoding for genes that can increase ability to cause disease or resist antibiotics. Genetic Diversity Genetic Diversity Causes of Mutations During DNA replication process is highly accurate repair mechanisms minimize number of mutations efficiency of repair mechanisms can vary depends on rate of duplication Exposure to mutagens can increase the rate of mutation more than 1000- fold chemical agents (eg Nitrous oxide, ethidium bromide) radiation (eg UV, X-rays) Phenotype & Genotype Genome: The complete set of genetic material including chromosome and plasmids, gene and noncoding DNA Genotype: Full collection of genes in genome Phenotype: Observable characteristics and activities Defined by the set of genes expressed at any one time Constitutive genes are always expressed https://courses.lumenlearning.com/microbiology/chapter/structure-and-function-of- Housekeeping are necessary for cellular-genomes/ the basic functions of the cell.  Gene Regulation Structural genes encode products that serve as cellular structures or enzymes Central Dogma Regulatory genes encode products that regulate gene expression Small RNAs Transcribed but not translated Typically ~50–400 nt long Regulatory role https://courses.lumenlearning.com/microbiology/chapter/structure-and-function-of- cellular-genomes/  Gene Regulation Promoter A DNA sequence upstream of a gene (or a set of genes) where transcription machinery (RNA polymerase) binds and https://courses.lumenlearning.com/wm-biology1/chapter/prokaryotic-transcription/ initiates transcription -10 and -35 regions with consensus s Factors sequences σ Factors are regulatory proteins also known as transcription factors σ Factors bind to consensus sequences and recruit the RNA polymerase to https://www.frontiersin.org/articles/10.3389/fbioe.2014.00033/full activate transcription Gene Regulation Activators, Repressors and Inducers help cells respond to external stimuli Repressors suppress transcription keeping a gene “off.” Activators increase the transcription of a gene turning a gene “on.” Inducers are small molecules that can either activate or repress transcription by binding to repressor or activators Gene Regulation Operon A stretch of sequence on the chromosome (or plasmid) where structural proteins with related functions are usually encoded Transcribed together under the control of a single promoter forming a polycistronic transcript Simultaneous control of genes that will either all be needed at the same time, or none will be needed https://courses.lumenlearning.com/microbiology/chapter/structure-and-function-of- cellular-genomes/  Gene Regulation Regulon A group of several genes or operons that are turned on or off in response to the same signal by the same regulatory protein. The members of a regulon have separate promoters and are widely separated on fliA Regulon the chromosome. (flagellar biosynthesis s factor)  Gene Regulation Biological pathway Cellular processes are carried out by groups of interacting proteins Groups of sets of proteins known to They are spatially and temporally organized interact under particular conditions Their interactions lead to biological processes Interactions lead to a certain product fundamental to bacterial survival or a change in a cell. Metabolic pathways make possible the chemical reactions that occur in bacteria eg breaking down nutrients into energy molecules or build molecules.  Gene Regulation Biological pathway Cellular processes are carried out by groups of interacting proteins Groups of sets of proteins known to They are spatially and temporally organized interact under particular conditions Their interactions lead to biological processes Interactions lead to a certain product fundamental to bacterial survival or a change in a cell. Gene-regulation pathways turn genes on and off governing gene expression though the action of molecular regulators Gene Regulation Biological pathway Groups of sets of proteins known to interact under particular conditions Interactions lead to a certain product or a change in a cell. Signal transduction pathways move a signal from a cell's exterior to its interior through structures on their surface called receptors to specialized proteins that trigger a specific reaction in the cell.  Bacterial Taxonomy Taxonomy classifies organisms into naturally related groups based on a factor that Classification, nomenclature is common to each and identification are all interrelated areas of taxonomy Classification refers to the arrangement of organisms into taxonomic groups (taxa) based on similarities or relationships Nomenclature is naming an organism according to its characteristics (following well defined international rules) Introduction to Bacteria https://www.enago.com/academy/write- scientific-names-in-a-research-paper- bacteria/ THE END