microorganisms and microbiology Flashcards
microorganisms
organisms too small to be clearly seen by the unaided eye
prokaryotic cells
bacteria and archaea
their contents are not divided into compartments by membranes - open
eukaryotic cells
plants, animals, fungi
have a nucleus and other membrane-bound organelles that separate some cellular materials and processes from others
three domain system for microorganisms
bacteria
archaea
eukarya
bacteria
- usually single-celled
- most have cell wall with peptidoglycan
- most lack a membrane-bound nucleus
- live in extreme environments (including our bodies)
- both disease causing and non-disease causing exist
archaea
- distinguished from bacteria by unique rRNA sequences
- have unique membrane lipids
- many live in extreme environments
- some have unusual metabolic characteristics
- do not directly cause disease in humans
two classifications of eukarya
protists
fungi
protists
- unicellular, but generally larger than bacteria and archaea
- protozoa - animal like metabolism
- algae - photosynthetic
fungi
- unicellular or multicellular
viruses
acellular entities that must invade a host cell to multiply
viroids
infectious agents composed only of ribonucleic acid
satellites
composed of a nucleic acid enclosed in a protein shell
must coinfect a host cell with a virus, called a helper virus, to complete their life cycle
prions
infectious agents composed only of protein, responsible for causing neurological diseases such as scrapie and mad cow disease
ribozymes
catalytic RNA molecules
RNA molecules that form peptide bonds
RNA world
describes the precellular stage in the evolution of life
- must of had lipid membrane formed around RNA
evidence of RNA world hypothesis
- most cellular RNA in modern cells exists in and is associated with the ribosome to construct proteins
- rRNA catalyzes peptide bond formation in protein synthesis
- similar structures indicate RNA may be precursor to double stranded DNA
- the energy source of current cells is a ribonucleotide (ATP)
- RNA can regulate gene expression
last universal common ancestor
- most recent organism from which all three types of life arose
- archaea and eukarya evolved independently of bacteria
taxonomy
science of classifying living things
- classification
- nomenclature
- identification
strain
descendants of a single, pure microbial culture
- can be characterized biochemically, morphologically, or pathogenically
microbiology
study of microorganisms and the tools used for the study
pure culture
aka axenic culture
isolated strain - removed from their normal habitats and grown in isolation
francesco stelluti
earliest microscopic observation
bees and weeviles btw 1625 and 1630
robert hooke
published drawing of the fungus Mucor in 1665
antony van leeuwenhoek
first person to observe microorganisms accurately
1632-1723
spontaneous generation
belief that living organisms could develop for nonliving matter
- discredited by francesco redi 1626-1697 - showed maggots on decaying meat came from fly eggs
john needham
based on observation that boiled hay gives rise to microorganisms
- thought life from nonliving material
1713-1781
lazzaro spallanzani
proved that they hay itself didn’t make microorganisms if in sealed environment
1729-1799
louis pasteur
- swan-neck flask experiments
discredited spontaneous generation
john tyndall
demonstrated that dust carries microorganisms
no dust = nutrient broths remained sterile, even if directly exposed to air
also provided evidence for the existence of exceptionally heat-resistant forms of bacteria
- discredited spontaneous generation
1820-1893
ferdinand cohn
showed heat-resistant bacteria could produce endospores
- discredited spontaneous generation
1828-1989
4 bodily-fluid humors infectious diseases were believed to be due to
blood, phlegm, yellow bile (choler), and black bile (melancholy)
scientist who found early evidence for the relationship between microorganisms and disease
- agostine bassi (1773-1856)
showed a disease of silkworms was caused by a fungus - M. J. berkeley (1803-1889)
demonstrated the potato blight of ireland was casued by a protozoan - heinrich de bary (1831-1888)
showed fungi caused crop disease - louis pasteur (1882-1895)
demonstrated microorganisms carried out fermentation - joseph lister (1827-1912)
provided indirect evidence that microorganisms were the causal agents of disease
developed an antiseptic surgery system to prevent microorganisms from entering wounds
robert koch
1843-1910
koch’s postulates - provides the causal relationship btw a microorganisms and a specific disease
- demonstrated that mycobacterium tuberculosis causes tuberculosis
limitations of koch’s postulates
- some organisms cannot be grown in pure culture bc they rely on host cells
- lack animal model
- using humans in completing the postulates is unethical
- molecular and genetic evidence may replace and overcome these limits
steps in koch’s postulates
- the microorganisms must be present in every case of the disease but absent from healthy organisms
- the suspected microorganism must be isolated and grown in a pure culture
- the same disease must result when the isolated microorganisms is inoculated into a healthy host
- the same microorganisms must be isolated again from the diseased host
immunological studies
- edward jenner (1749-1823)
used vaccination procedure to protect against smallpox - emil von behring (1854-1917) and shibasaburo kitasato (1852-1931)
developed antitoxins (antibodies) for diphtheria - elie metchnikoff (1845-1916)
discovered first immune system cells - phagocytic cells in blood engulf bacteria
