bacteria viruses09martin
DESCRIPTION
Overview of microorganisms (bacteria and viruses)TRANSCRIPT
Viruses and Viruses and BacteriaBacteria
VirusesViruses
Living or Non-Living?
•Infectious particles of nucleic acid and proteins
•Cannot “live” (reproduce) outside a host
History/Discovery
1883 Adolf Mayer sought cause of Tobacco Mosaic Disease
1935- Wendell Stanley crystallized the infectious particle—determined it was NONLIVING (can’t crystallize cells)
1st virus discovered-Tobacco Mosaic Virus (TMV)
Virus StructureVirus Structure
Very small and simple (smaller than Very small and simple (smaller than a ribosome ~20nm in diameter)a ribosome ~20nm in diameter)
Made of DNA or RNA surrounded by a Made of DNA or RNA surrounded by a protein coat (capsid) protein coat (capsid)
Characteristics
Host specific—identify host cells by Host specific—identify host cells by “lock and key” fit between proteins “lock and key” fit between proteins on virus and host cell receptorson virus and host cell receptors
*Presumed that receptors first *Presumed that receptors first evolved because they carried out evolved because they carried out some functions that benefited the some functions that benefited the organismorganism
Naming Viruses
International Committee on Taxonomy of Viruses names them based on three characteristics: Type of nucleic acid (DNA or RNA) Is the nucleic acid double or single
stranded Presence or absence of nuclear
envelope
Viral InfectionViral Infection
Lytic Infection-Lytic Infection- virus enters the cell, virus enters the cell, makes copies of itself, and causes makes copies of itself, and causes the cell to burstthe cell to burst
Lysogenic Infection-Lysogenic Infection- virus integrates it virus integrates it DNA into the DNA of the host. Viral DNA into the DNA of the host. Viral DNA replicates with host DNADNA replicates with host DNA
Viral Reproduction
Steps of Lytic Cycle Attachment Entry Replication Assembly Lysis/Release (lyses the cell)
RetrovirusesRetroviruses
Contain RNA instead of DNA Contain RNA instead of DNA Copy their RNA into DNA instead of Copy their RNA into DNA instead of
DNA to RNADNA to RNA
Examples: AIDS, some cancersExamples: AIDS, some cancers
BacteriaBacteria
Most numerous and widespread Most numerous and widespread organismsorganisms
““Discovered” with the invention of Discovered” with the invention of the microscope by Robert Hooke and the microscope by Robert Hooke and Anton van Leeuwenhoek (1676)Anton van Leeuwenhoek (1676)
ClassificationClassification
Two kingdoms of Two kingdoms of Prokaryotes Prokaryotes (Prokaryotes (Prokaryotes are organisms that lack are organisms that lack nuclei or membrane-bound organelles)nuclei or membrane-bound organelles)
Kingdom EubacteriaKingdom Eubacteria: “true bacteria” , : “true bacteria” , variety, 3 shapes, no phylavariety, 3 shapes, no phyla
Kingdom Archaebacteria: Kingdom Archaebacteria: “ancient”, “ancient”, lives in extreme environmentslives in extreme environments
ArchaebacteriaArchaebacteria Methanogens–live in large intestines Methanogens–live in large intestines
of animals, decompose dead of animals, decompose dead organisms, produce methane gas organisms, produce methane gas (CH(CH44))
Halophiles--live in salty environmentsHalophiles--live in salty environments
Thermoacidophiles—live in hot, acidic Thermoacidophiles—live in hot, acidic environmentsenvironments
Size and StructureSize and Structure
1-5 micrometers (much smaller than eukaryotic 1-5 micrometers (much smaller than eukaryotic cells– 10-100 micrometers)cells– 10-100 micrometers)
Unicellular (although grow in colonies)Unicellular (although grow in colonies)
Prokaryotic- no nucleus, no membrane-bound Prokaryotic- no nucleus, no membrane-bound organellesorganelles
* CAN IDENTIFY BACTERIA BASED ON:* CAN IDENTIFY BACTERIA BASED ON:
Shape, Cell Wall, and MovementShape, Cell Wall, and Movement
Method of Obtaining Energy
Most are heterotrophic (mostly decomposers)
Some are autotrophic—chemotrophs and photoautotrophs
Ex: cyanobacteria
ShapeShape Coccus (spherical)*Coccus (spherical)*
Bacillus (rod-shaped)*Bacillus (rod-shaped)*
Spirillum (spiral-shaped)*Spirillum (spiral-shaped)*
*Arranged in chains, groups, or pairs*Arranged in chains, groups, or pairs Pair– Diplo-Pair– Diplo-
Chains– Strepto-Chains– Strepto-
Groups– Staphylo—Groups– Staphylo—
**Example: Spherical shaped bacteria arranged in **Example: Spherical shaped bacteria arranged in chains would be named, “Streptococcus”chains would be named, “Streptococcus”
Cell Wall
For Eubacteria only! Gram negative- thin cell wall
consisting of a few layers of peptidoglycan
Gram positive- thick cell wall consisting of many layers of peptidoglycan
Typical Bacterial CellTypical Bacterial Cell
Cell wallCell wall
Cell membranesCell membranes
DNA (floating freely)-circular DNA (floating freely)-circular chromosomechromosome
RibosomesRibosomes
Some can move (flagella, others glide)Some can move (flagella, others glide)
ReproductionReproduction
Most bacteria reproduce by Most bacteria reproduce by Binary FissionBinary Fission
Produces 2 identical “daughter” cellsProduces 2 identical “daughter” cells
Can grow and divide every 20 minutesCan grow and divide every 20 minutes
Asexual (no exchange or recombination of genetic Asexual (no exchange or recombination of genetic information)information)
Image of E. coli going through Binary fission
Ways bacteria can accomplish genetic recombination
(variation) Conjugation- exchange of genes from 1 bacterial cell
to another
Transformation-bacteria take up pieces of free DNA
from another bacterial cell
Transduction- bacteriophage transfer portions of
bacterial DNA from one cell to another.
E.coli undergoing conjugation
““BAD” BacteriaBAD” Bacteria
Food Spoilage—Food Spoilage—smells, makes you sicksmells, makes you sick
Bacterial DiseasesBacterial Diseases Only 3% of all bacteria cause human diseasesOnly 3% of all bacteria cause human diseases Can be treated with antibiotics and prevented Can be treated with antibiotics and prevented
through vaccinationthrough vaccination 11stst antibiotic discovered/source antibiotic discovered/source Examples: pneumonia, bubonic plague, Strep. Examples: pneumonia, bubonic plague, Strep.
Throat, Syphilis, gonorrhea, anthrax, botulismThroat, Syphilis, gonorrhea, anthrax, botulism
E. coli
““GOOD” Bacteria: The GOOD” Bacteria: The Importance of BacteriaImportance of Bacteria
DecomposersDecomposers Help ecosystem recycle nutrientsHelp ecosystem recycle nutrients Breakdown complex compounds into Breakdown complex compounds into
usable materialsusable materials Nitrogen fixersNitrogen fixers
Bacteria perform nitrogen fixationBacteria perform nitrogen fixation
Importance of Bacteria Importance of Bacteria (Cont.)(Cont.)
Human UsesHuman Uses Production of food and beveragesProduction of food and beverages Medicine and chemical industryMedicine and chemical industry Genetic engineeringGenetic engineering Bioremediation: Cleaning up the Bioremediation: Cleaning up the
environmentenvironment