The Basics of The Basics of BacteriaBacteria

What are bacteria?What are bacteria? Bacteria areBacteria are single-celled single-celled

prokaryotesprokaryotes DNA is not located in a nucleusDNA is not located in a nucleus

Bacteria appeared on Earth at least Bacteria appeared on Earth at least 3.5 billion years ago3.5 billion years ago

Bacterial ShapesBacterial Shapes Most bacteria have Most bacteria have

one of the following one of the following shapesshapes::BacilliBacilli CocciCocciSpirillaSpirilla

Bacterial StructuresBacterial Structures Most bacteria have the following Most bacteria have the following

structuresstructures:: Cell wallCell wall (contains peptidoglycan, (contains peptidoglycan,

a compound composed of amino a compound composed of amino acids and carbohydrates)acids and carbohydrates)

Cell membraneCell membrane CytoplasmCytoplasm ChromosomeChromosome (Single-loop of DNA) (Single-loop of DNA)

Additional Bacterial Additional Bacterial StructuresStructures

Some bacteria may have the following Some bacteria may have the following structures:structures: CapsuleCapsule (covering outside of cell wall that (covering outside of cell wall that

protects bacterial cell)protects bacterial cell) PiliPili (hair-like structures used to transfer (hair-like structures used to transfer

genetic material from one bacterium to genetic material from one bacterium to another)another)

EndosporeEndospore (Thick covering around DNA; (Thick covering around DNA; developed under harsh conditions)developed under harsh conditions)

PlasmidPlasmid (small, additional loop of DNA) (small, additional loop of DNA) FlagellaFlagella (Used for motion) (Used for motion)

Nutrition and GrowthNutrition and Growth Bacteria Bacteria obtain their energyobtain their energy in in

one of two ways:one of two ways:Heterotrophs Heterotrophs (must obtain (must obtain

“food” for energy)“food” for energy)AutotrophsAutotrophs (obtain energy (obtain energy

from sunlight or minerals)from sunlight or minerals)

Nutrition and Growth Nutrition and Growth continuedcontinued

Oxygen requirementsOxygen requirementsObligate anaerobesObligate anaerobes (can’t (can’t

survive in presence of oxygen)survive in presence of oxygen)Facultative anaerobesFacultative anaerobes (don’t (don’t

require oxygen, but can survive require oxygen, but can survive around it)around it)

Obligate aerobesObligate aerobes (require (require oxygen)oxygen)

Bacterial ReproductionBacterial Reproduction Bacteria reproduce byBacteria reproduce by binary binary

fissionfission:: One cell divides to form One cell divides to form

two identical cellstwo identical cells

http://www.yteach.com/index.php/resources/amino_acids_antibiotics_autotroph_protein_cell_wall_chemoautotrophic_chemosyntesis_chlorophyll_saccharides_carbohydrates_cytoplasm_DNA_energy_enzyme_evolution_fermentation_phospholipids_histone_nucleus_DNA_RNA_population_t_page_37.html

Genetic RecombinationGenetic Recombination If bacteria reproduce “clones” by If bacteria reproduce “clones” by

binary fission, binary fission, why aren’t all bacteria why aren’t all bacteria identical?identical? Transformation:Transformation: cell takes in DNA from cell takes in DNA from

environment and replaces a portion of its environment and replaces a portion of its own DNA with this new DNAown DNA with this new DNA

Conjugation:Conjugation: A bacterium attaches its A bacterium attaches its pilus to another cell and transfers a copy of pilus to another cell and transfers a copy of its plasmid to this cellits plasmid to this cell

Transduction:Transduction: Virus “infects” a Virus “infects” a bacterium with a piece of bacterial DNA it bacterium with a piece of bacterial DNA it is carrying from a different bacterial cellis carrying from a different bacterial cell

TransformationTransformation

transformation and conjugation videohttp://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter13/animation_quiz_1.html

ConjugationConjugation

http://www.hhmi.org/biointeractive/animations/conjugation/conj_frames.htm

TransductionTransduction

http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter13/animation_quiz_2.html

http://faculty.ircc.edu/faculty/tfischer/images/specialized%20transduction.jpg

Bacterial DefensesBacterial Defenses Bacteria have numerousBacteria have numerous

defenses against the threats in defenses against the threats in their environment:their environment:Exotoxins:Exotoxins: Poisonous proteins Poisonous proteins

secreted by bacteriasecreted by bacteriaEndotoxins:Endotoxins: Toxin in bacterial Toxin in bacterial

cell wall; released when cell wall; released when bacteria diebacteria die

Naturally-Occurring Naturally-Occurring AntibioticsAntibiotics

AntibioticsAntibiotics Chemicals that interfere with cell Chemicals that interfere with cell

functions; inhibit bacteria growth.functions; inhibit bacteria growth.Bacteria are Bacteria are sensitivesensitive if they if they

don’t grow in the presence of don’t grow in the presence of the antibiotic.the antibiotic.

Bacteria are Bacteria are resistantresistant if they do if they do grow in the presence of the grow in the presence of the antibiotic.antibiotic.

Bacteria Growth and Bacteria Growth and AntibioticsAntibiotics

http://www.sumanasinc.com/scienceinfocus/sif_antibiotics.html