Monday, 8 July 2013

Microbiology I

This The First of new series of  Notes in Pharmaceutical Sciences, wait for more

Microbiology is the study of organisms from three domains as well as acellular entities that are not considered to be living in the biological sense.
A. Domains of living organisms
1. Archaea (constitute a domain or kingdom of single-celled microorganisms. These microbes have no cell nucleus or any other membrane-bound organelles within their cells.) include prokaryotes with cell walls that are biochemically different from bacteria and that inhabit extreme environments of heat , cold, pH, or salts. Archaea are not a medically important domain of microorganisms.
2. Eukarya (A eukaryote is an organism whose cells contain complex structures enclosed within membranes.) contains some microorganisms—for example, fungi (yeasts and molds) , protozoa, and algae—along with macroscopic organisms such as mushrooms, plants, and animals. Dimorphic fungi are those that can exist in either the unicellular (yeast ) or the filamentous (mold) phase, depending on the incubation temperature (e.g. , Histoplasma and Blastomyces) .
a. Fungi are classified into phyla based on the type of reproductive structures observed or the lack of observable sexual reproductive structures.
(1) Ascomycota (ascus) (e.g. , Candida and Histoplasma)
(2) Basidiomycota (basidium) (e.g., Cryptococcus)
(3) Zygomycota (zygote) (e.g. , Rhizopus)
(4) Deuteromycota (asexual , also called fungi imperfecti ) (e.g., Coccidioides).
Recently, some sexual reproductive states have been identified in fungi classifiedas belonging to Deuteromycota.
b. Protozoa, unicellular , nonphotosynthetic eukaryotes characterized by mode of motility, include the following:
(1) Mastigophora (flagellates) (e.g. , Giardia)
(2) Sarcodina (amoebae) (e.g. , Entamoeba)
(3) Ciliophora (ciliates) (e.g., Balantidium)
(4) Sporozoa (nonmotile) (e.g. , Plasmodium)
3. Bacteria contain a wide variety of prokaryotes, including gram-positive and gram-negative bacteria.
B. Nonliving, but medically significant entities are the following
1. Viruses, which are classified by:
a. Capsid structure, which is the protein coating around the nucleic acid
b. Type and st randedness of nucleic acid, which could be DNA or RNA, either
single or double stranded
c. Presence or absence of a lipid envelope surrounding the protein capsid
d. Presence of enzymes, which may be either incorporated into the lipid envelope or found in the capsid near the nucleic acid
2. Prions, infectious proteins, are implicated in some spongi-form
encephalopathies (e.g. , mad cow disease, Creutzfeldt-Jakob disease, and kuru) .

Comprehensive Pharmacy Review





Google+ Followers

Follow us by Email