Microbiology Flashcards
Microorganisms
Organisms and unicellular biological entities too small to be seen by the naked eye.
Phylogenetic Tree
A diagram used to reflect evolutionary relationships among organisms. Scientists consider phylogenetic trees to be a hypothesis of the evolutionary past since one cannot go back to confirm the proposed relationships.
Thomas Cech
Discovered catalytic RNA molecule in protist (ribosomes)
RNA world
A stage in life to describe precellular stage in evolution of life in which RNA was capable of storing, copying, and expressing genetic information.
Endosymbiotic hypotheses
Accepted for mitochondria, chloroplasts and hydrogenosomes. One organisms lived inside the other. Maybe one lost the ability to live independently.
Species
Group of interbreeding natural populations that is reproductively isolated from other groups.
Strain
Consists of the descendants of a single, pure microbial culture. There are strains within a species. Bacteria and archae are strains because they do not reproduce sexually.
Carl Linaeus
Taxonomy. Named, identified and classifying organisms.
Microbiology
The study of microorganisms and the tools used to study them.
Robert Hooke
First drawings of microorganisms in “Micrographia”.
Spontaneous generation
Living organisms could develop from nonliving matter.
Robert Koch
Koch’s Postulates: injected mice with anthrax from ill animals proving Bacillus anthracis was the cause. Also invented nutrient broth with help of Fanny Hesse (assistants wife).
Richard Petri
Devised the petri dish.
Charles Chamberland
Chamberland’s filter is used to trap bacteria. Viruses got through suggesting that viruses were smaller.
Louis Pasteur
French chemist that played a role in fermentation, vaccines, and pasteurization.
Brght-field microscope
Used to view stained and unstained specimens. Forms a dark image against a brighter background.
Parfocal
Image should remain in focus when objective lens are changed.
Resolution
Ability of a lens to distinguish between small objects that are close together.
Refraction
Light passes through one medium to another. The measure of how greatly a substance slows the velocity of light is the refraction index.
Dark-field microscope
Produces details images of living, unstained cells by changing the way in which they are illuminated. A dark-field stop is placed under the condenser so only the only light you see is coming from the specimen.
Fluorescence microscope
Excites a specimen using a specific wavelength if lights and forms an image with the fluorescent light emitted by object.
Confocal miscroscope
Useful in viewing 3D objects such as a biofilm. An aperture placed above the objective lens eliminates tray light from below and above specimen.
Fixation
Process by which internal and eternal structures of specimens are preserved and fixed into position. Inactivates enzymes to not disrupt cell morphology and toughen structures so that they do not change during staining.
Heat fixation
Use of heat to fixate specimen to slide. Denatures proteins.
Chemical fixation
Use of chemicals to fixate specimen. Protects fine cellular substructures as well as morphology. Used for more delicate or larger specimens.
Simple Stain
Single dye is used
Negative Stain
Background is stained, not cell
Differential staining
Using more than one dye that will distinguish organisms based on their staining properties (positive or negative). Other differential staining is used for particular structures such as capsules or endospores.
Bacteria
Unicellular microorganisms which have cell walls but lack organelles and an organized nucleus, including some that can cause disease.
Pathogen
A bacterium, virus, or other microorganism that can cause disease.
Cocci morphology and arrangement
- Spherical
- Diplococci: pairs
- Streptococci: chains
- Staphylococci: clusters
- Tetrads: square
- Sacinae: cubic configuration of 8
Bacilli morphology and arrangement
- Rods
- Coccobacilli: short rods
- Vibrios: comma shaped rods
Other cell morphology and arrangement
- Spirilla: shaped like helices; not flexible
- Spirochetes: flexible helices
- Mycelium: networks of long, multinucleate filaments
- Pleomorphic: look like blobs; no rigid cell wall
Functions of plasma membrane
- Separation of cell from environment
- Selectively permeable barrier
- Metabolic processes
- Receptor molecules
Surface area-to-volume ratio
As ratio increases, the uptake of nutrients and the diffusion of these and other molecules within the cell become more efficient facilitating growth.
Mesosomes
- Function not agreed upon
- Very small internal structures
Microbial Growth
Increase in cellular constituents that may result in increase in cell number or increase in cell size.
Cell Cycle
Complete series of events extending from the formation of a new cell through the next division.
Biofilm
- Slime-encased microbe community
- Can form on almost any surface
- Made up of polymers such as proteins, glycoprotiens, polysaccharides
Cell
Smallest unit that can live on its own and makes up living organisms
Four type of cells
Epithelial
Muscle
Nerve
Connective
Organ
Structure composed of two or more types of tissues
