MicrobesClick Viruses for additional information.
General Notes:
Viruses - non-living
Characteristics
Made up of fragments of a genome, strands of nucleic acid encased in protein coats
Possess only one form of nucleic acid, either DNA or RNA depending on the virus type
Cannot grow or replicate without a host
Replicate only utilizing host cell`s machinery
Ecology
Important due to disease producing potential
Could never have existed independently as preexisting organisms
Viruses are often highly host-specific, reproduce only within a certain host
Mode of action
Transmit nucleic acid component from one host cell to another
Nucleic acid takes over host cell and produces more viruses
Virulent viruses cause host cell to lyse and release new virus particles
Temperate viruses become established in genome of host cell
Bacteria:
Archaea
many species found in extreme environments
thermoacidophiles - hot springs
halophiles - salt lakes, deep sea hydrothermal vents, involved in decomposition
methanogens - swamps, marshes (die in the presence of oxygen), decomposers
found in the gut of some animals, used to make methane from garbage
Bacteria
Characteristics of most species
cell wall made up of peptioglycan (sugar and proteins), gram + or -
flagella in some species
no membrane-bound organelles
genome - sinlge strand of DNA and maybe circular DNA (plasmid)
reproduction by binary fission
some species produce endospores to survive in harsh environments
small size
Metabolism and Ecology - aerobic and anaerobic
autotrophs
photosynthetic - derive energy from photosynthesis
chemosynthetic - derive energy from oxidation of inorganic compounds (hydrogen sulfide, ammonia, etc...)
heterotrophs
saprobes - decomposers
parasites
TB, STD's (Gonorrhea, Syphillis, Chlamydia) , Lyme Disease, tooth decay and halitosis
nitrogen metabolism - processing of nitrogen
nitrogen fixation - converts nitrogen gas directly from nitrogen in the atmosphere into ammonium that can be used
by plants or by the bacteria themselves (cyanobacteria with heterocyst)
Oxygen and prokaryotic metabolism
obligate aerobes - must have oxygen for cellular respiration
facultative anaerobes - will use oxygen in respiration when it is available but can also use fermentation to produce
energy for their cells
obligate anaerobe - only use fermentation, oxygen is poisonous
Major forms
bacilli
cocci
spirilli
Gram + bacteria - cell wall is composed almost entirely of peptidoglycan
Gram - bacteria - cell wall is composed of an outer membrance with peptidoglycan
5 Major Groups of Bacteria
Proteobacteria (gram - bacteria)
broad diversity of species and ecologies
many species are symbiotic (parasites or mutualists)
some photoautotrophs and chemoautotrophs
Chlamydia
parasites (use ATP from host cell)
Spriochetes
some free-living and some parasitic forms (Lyme Disease)
Gram + bacteria (includes some gram - bacteria)
broad diversity of species and ecologies
fungus-like bacteria
parasites - tuberculosis and leprosy
free-living in soil - decomposers and some species used to make antibiotics
spore-forming bacteria - causes botulism, other diseases (staph and strep throat infections)
mycoplasmas - only bacteria that lack cell wall
free-living in soil
pathogens - walking pneumonia
Cyanobacteria - blue-green algae
photosynthetic autotrophs
Putting prokaryotes to work
sewage treatment
bacteria used to clean up oil spills
make yogurt, acetic acid, vinegar
used in recombinant DNA experiments
This next site links you directly to the textbook which we use in class. What you find here is an "interactive" site that will reinforce or help clarify all that we cover in class. You will also find practice tests to help you learn the information and better prepare you to be successful in this course. I encourage all of you to use this site frequently. There are links to other sites that will help you understand the concepts and to see ideas / facts presented in different ways. This will help reinforce the learning process. Good luck!
Try this exciting site. It will take you to a "Microbe Zoo" and you can explore the many interesting and interactive activities. To get a really upclose look at the many types of microbes and where they might be lurking.
This is an excellent site. It is the PinkMonkey.com section on Viruses, the Kingdom Monera,the Kingdom Protista, the Kingdom Plantae and the Kingdom Fungi. I highly recommend you review this chapter to reinforce what we are covering in class.
Bacterial resistance to antibiotics is a growing health problem. Learn more about this by clicking on the following link.