Introduction to Microbiology

Study Notes

Microbiology is the study of microorganisms that exist in unicellular, multicellular, or acellular forms and must be viewed individually with the aid of a microscope.
Microorganisms include eukaryotes, prokaryotes, viruses, viroids, and prions.

Medicine: vaccine development, production of antibiotics, and biological enzymes
Industry: production of beer, wine, cheese, and yogurt
Agriculture: maintenance of soil fertility, improvement of plant growth and productivity
Veterinary microbiology: study of veterinary medicine and vaccines
Environmental microbiology: study of the role of microorganisms in maintaining ecosystem balance and their use in ecosystem improvement

Characteristics: organisms with cells that have a nucleus and other membrane-bound organelles
Examples: animals, plants, algae, nematodes, fungi, and protozoa

Characteristics: unicellular organisms that lack a membrane-bound nucleus and other membrane-bound organelles
Examples: bacteria and archaea

Characteristics: prokaryotes with ether linkages in their cell membrane, lacking peptidoglycan in their cell walls, and having genes and enzymes similar to those of eukaryotes
Differences from bacteria: cell membrane, cell wall, and RNA polymerase

Definition: a small, circular, extra double-stranded DNA molecule that is distinct from a cell's chromosomal DNA
Characteristics: can replicate independently, usually small, and contains additional genes that may be useful to the organism under certain conditions

Definition: a complex network of interlinking filaments and tubules that extends throughout the cytoplasm
Functions: provides shape to the cell, helps in mitosis by chromosomal separation

Definition: an acellular, ultramicroscopic, metabolically inert, infectious agent that replicates only within the cells of living hosts
Characteristics: contains either RNA or DNA, has a protein coat called the capsid, and may have an envelope of lipids and proteins
Functions: attaches to and enters host cells, replicates, and assembles into new viral particles

Definition: proteinaceous infectious particles composed of abnormally folded protein
Characteristics: causes disease similar to viral infection, attached to normal proteins inside neurons, and causes them to take on the shape of the prion, leading to disease
Examples: Creutzfeldt-Jakob disease, fatal familial insomnia, and kuru

Definition: small, circular RNA molecules without a protein coat
Characteristics: replicate through a rolling circle mechanism, cause diseases in plants, and are "sub-viruses"

Definition: a product that stimulates a person's immune system to produce immunity against a specific disease
Types: live, attenuated, inactivated, subunit, toxoid, and conjugate vaccines

Definition: specific defenses against a particular disease
Types: active immunity (following clinical infection or vaccination) and passive immunity (transfer of maternal antibodies or administration of immunoglobulin or antiserum)

Vaccines: stimulate the production of antibodies and provide immunity against one or more diseases
Immunoglobulins: provide immediate immunity against a specific disease
Antisera: provide immediate immunity against a specific disease

Live, attenuated vaccines: contain a weakened form of the living microbe, elicit strong cellular and antibody responses, and often confer lifelong immunity with only one or two doses
Inactivated vaccines or killed vaccines: contain a killed form of the disease-causing microbe, stimulate a weaker immune system response, and may require several doses
Subunit vaccines: contain a fragment of the microbe, rather than the entire microbe, and stimulate an immune response
Toxoid vaccines: contain inactivated toxic compounds that cause illness, rather than the microbe itself
Conjugate vaccines: contain a polysaccharide outer coat linked to a protein, which leads to recognition of the polysaccharide as a protein antigen
Recombinant vector vaccines: use a manipulated microorganism to transport genes to cells to code for a needed protein or hormone