240 likes | 487 Views
Microbes and Society. Brief Introduction to Microbes. Prokaryotes vs. Eukaryotes. Prokaryotes have no membrane bound nucleus or organelles. They have a single closed loop of DNA. Most of the prokaryotes reproduce by fission.
E N D
Microbes and Society Brief Introduction to Microbes
Prokaryotes vs. Eukaryotes • Prokaryotes have no membrane bound nucleus or organelles. They have a single closed loop of DNA. Most of the prokaryotes reproduce by fission. • Eukaryotes have both membrane bound nuclei and organelles. They have DNA that are formed into chromosomes. Some reproduce through fission but most reproduce sexually.
Nomenclature • “Living” Organisms have both a common and a scientific name • Genus name is always capitalized while species name is not. Both are italicized or underlined. • For example, the black-legged tick (common name) has a scientific name of Ixodes scapularis. • Virus only have common names as they are not considered “living” organisms.
Examples of Prokaryotes Borrelia Ehrlichia Staphylococcus
Morphology of Bacteria Coccus or Round
More Shapes Bacilli or Rods
Gram-Negative vs. Gram Positive Bacteria • An easy way to categorize 2 “types” of bacteria. • Dye bacteria using crystal violet and iodine. Gram-positives “soak” up the purple dye, gram negatives don’t. Then rinse in alcohol and counter stain with safranin. Gram-negatives stain orange-red while gram-positives stay purple. • So, what good is this?
Functions of Bacteria • Commensals • Photosynthesis • Nitrogen fixation • Pathogens • Medicine (Recombinant) • Research • Others!!!!
Types of Virus • They are simple, very small, and utilize others for help in reproduction. • Shapes include: • Helical, e.g. bacteriophage M13 • Polyhedral/cubic, e.g. poliovirus • Enveloped - may have poyhedral (e.g. herpes simplex) or helical (e.g. influenzavirus) capsids • Complex, e.g. poxviruses
Other way to categorize Virus using nucleic acid • Some virus have double stranded DNA (like us) • Others have single stranded RNA (for example HIV)
Viral Replication • There are 5 major steps in the replication cycle of all viruses: • Attachment • Penetration • Nucleic acid and protein synthesis • Assembly of virions • Release/egress
Functions of Virus • Pathogens • Can be the cause of certain cancers • Utilized in research- may be used to cure diseases through gene therapy • http://www.edu365.cat/aulanet/comsoc/Lab_bio/simulacions/GeneTherapy/GeneTherapy.htm
Protists • Eukaryotic, these include protozoa, certain types of algae and a few others • Four types of protozoans • Amoebas • Flagellates • Ciliates • Apicomplexans.
Amoebas • They can change their shape and move by sending out pseudopodia. Water-borne amoebas cause amoebic dysentery.
Flagellates • Move using flagella, this group causes diseases such as African sleeping sickness, common venereal disease- Trichimonas, and Giardia (or beaver fever) Trichomonad of cattle
Ciliates • Tiny hairlike projections all over the surface beat in networks along the cell which allows the organisms to move forward, backwards and rotate. They are also capable of sexual recombination. • There is only 1 ciliate spp. Pathogenic to humans.
Apicomplexans • Many are intracellular in parts of their life cycle, they have organelles that allows them to gain access into cells. • Malaria-up to 2 million/year die • Toxoplasma- dangerous for immunocompromised/preganant women • Pneumocystis carinii- one of the leading causes of death in AIDS patients
Fungi • Yeasts- lots of positive uses including fermentation that leads to bread rising, and alcohol production. • Some yeasts can cause infection (thrush or yeast infections) • Molds- Decomposers that are sometimes compacted together known as a mushroom • Lichens-part fungus part other (cyanobacteria) • Ringworm