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298 Cards in this Set
- Front
- Back
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What is microbiology
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study of microorganisms that carry out one or more life processes and are typically too small to be seen by the naked eye
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What the the life processes
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ability to replicate, grow, metabolize and respond to the environment. all living cells carry these out.
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What are the seven major types of microorgansims or microbes
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bacteria, archaea, fungi, protozoa, algae, helminths and viruses
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What are bacteria and archaea. How are they different
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small, simple, single-celled organisms that are prokaryotic. They differ in ribosomal structure, cytoplasmic membrane structure and cell wall structure. (Archaea do not have peptidoglycan cell walls)
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What makes up the bacteria cell walls
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peptidoglycan
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What are the two types of archaea
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Methanogens-obligate anaerobes that produce methane gas
Extremophiles-live under extreme conditions of temperature, pH or salinity |
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What are fungi
What are there cell ways made up of What is there metabolism like What do they require |
unicellular or multicellular organisms that are eukaryotic, cell walls composed of chitin or cellulose
Have a plant like absorptive metabolism, require an organic source of carbon and do not carry out photosynthesis. Includes mushrooms, yeasts, and molds |
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What are protozoa
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unicellular organisms that are eukaryotic, lack cell walls, require an organic source of carbon, and do not carry out photosynthesis
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What two types of microbes require an organic source of carbon and do not carry out photosynthesis
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Protozoa and fungi
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What are algae
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unicellular and multicellular organisms that have a eukaryotic cell structure, carry out photosynthesis
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What are helminths
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parasites of humans that are multicellular eukaryotes that lack cell walls
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What are algae cell walls composed of
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a polysaccharide and other substances e.g. cellulose, agar, silica, calcium carbonate
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What are some examples of parasitic helminths
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schistosoma mansoni (blood fluke) tapeworm, roundworm, guinea worm
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What are viruses
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non living cells that are acellular and are too small to be seen with a light microscope. can replicate inside living cells but not by themselves
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What are viruses composed of
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a nucleic acid, a protein coat, and sometimes a membrane coat
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How are microbes names
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Genus name then species name in latin
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What is a genus
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group of closely related species
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what is a species
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a group of organisms that interbreed with each other, but not with individuals from a different species. doesn't work with prokaryotic cells because they reproduce asexually
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what is a prokaryotic species
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a group of closely related cell strains- a group of cells that are derived from a single cell
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What do microbes do for the world
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they recycle bound vital elements such as carbon, nitrogen, oxygen, phosphorous, and sulfur, in dead plants, animals, and organic wastes into unbound forms that can be reused by living organisms
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What type of microbes produce most of the oxygen in the atmosphere
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photosynthetic microbes
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What do photosynthetic marine microbes do
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convert co2 into energy rich organic compounds that marine animals use for food
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What are plankton
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basis for the food chain the the oceans and make marine animal life possible
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What do normal flora do
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help us maintain our health by inhibiting the growth of pathogenic microbe on our bodies by microbial antagonism and they supply us with essential vitamins
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How do microorganisms benefit the lives of humans
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help us maintain our health, produce many important foods and commercial products, they are used to make sewage safe and to clean up environmental pollution, and are used in agriculture to kill caterpillar pests and produce nitrogen fertilizer
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how are microbes used to make sewage safe and to clean up environmental pollution
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they remove organic matter and toxic pollutants from raw sewage in treatment plants, preventing it form polluting the environment, they are used as sensitive biosensors to detect the presence of toxic substances and pathogenic microbes in the environment, they are used to detoxify industrial dumps and chemical and oil spill sites, making them safe for inhabitation by humans and animals
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how do microbes adversely affect humans
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they cause infectious diseases, cause food spoilage and cause the weathering and breakdown of building materials, paints, leather and many other products
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Who made they first microscope capable of viewing microbes
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Antoni van Leeuwenhoek in 1673
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What happened before the discovery of microbes
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food spoilage could not be controlled, entire families would get sick and die from infectious disease, great pandemics of a dreaded disease called e black death would periodically appear killing millions
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What caused the bubonic plague (black death)?
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Caused by the bacterium Yersinia perstis
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What is Yersina pestis
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an endemic disease of wild rodents, usually spread to humans by Y. pestis infected rat fleas. (caused bubonic plague)
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Who disproved spontaneous gerneration
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Francesco Redi
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Who recovered the theory of spontaneous generation and how?
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John needham by beef in jars
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Who disproved spontaneous generation forever
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Louis Pasteur by proving biogenesis
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what is biogenesis
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the idea that living cells can only be formed by preexisting living cells
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what significant events happened in the golden age of microbiology
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Scientists developed methods for culturing and studying individual microbial species.
Discovered the role of microbes in causing fermentation, disease and food spoilage Developed methods for preventing infectious diseases Established the scientific method as the standard for investigating and answering science questions |
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What are the steps of the scientific method
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Observation, question, hypothesis, experiment, conclusion
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What important discoveries did Lauis Pasteur make
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Showed yeasts were responsible for fermentation and bacteria ruined wine by fermenting into acid
Developed pasteurization which is the heating of liquid foods to 63 degrees to kill the bacteria that cause wine spoilage Proposed germ theory of disease developed vaccines to prevent rabies and chicken cholera |
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Who was Robert Koch
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Proved that microbes can cause disease in animals. Did this by showing Bacillus anthracis was transmitted from cow to cow.
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What were some important discoveries of Robert Koch
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Showed Mycobacterium tuberculosis was the cause of tuberculosis.
Discovered delayed hypersensitivity Developed Koch's postulate. Laboratory techniques |
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What is Koch's postulate
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1. suspected causative agent must be found in all cases of the disease
2. agent must be isolated and grown outside the host 3. when agent is introduced to healthy host, host must get disease. 4. Same agent must be re-isolated from the diseased experimental host |
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Who invented vaccination
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Edward Jenner
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Who introduced hand disinfection for health care givers
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Ignaz Semmelweis
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Who introduced strict cleanliness standards to army hospitals
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Florence Nightingale
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Who used epidmiology to stop cholera epidemic
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John Snow
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Who introduced aseptic surgery
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joseph Lister
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Who discovered antibodies
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Emil von Behring
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Who discovered phagocytosis and proposed the theory of cellular immunity
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Elie Metchnikoff
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Who proposed the theory of humoral immunity and developed the first drug for treating an infectious disease. He is the father of chemotherapy
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Paul Ehrlich
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Who discovered the first antibiotic (penicillin)
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Alexander Fleming
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What is the most appropriate way to treat an infectious disease
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1. Isolate and identify the microbe causing the disease.
2. Test the isolated microorganism for sensitivity to antibiotics to determine which antibiotics kill it 3. treat the patient with the antibiotic most effective in killing the microbe causing the infection |
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What are some ways to prevent infectious disease
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1. vaccination
2. preventing their transmission to new hosts 3. by taking appropriate infection control measures, medical/dental personnel can reduce the risk of disease transmission between themselves and their patients |
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What are some diseases that can be transmitted in medical and dental facilities?
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Tuberculosis, Group A Streptococcus, Syphilis, Flu, colds, Hepatitis B, AIDS, Herpes
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What is Microscopy
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the use of visible light or electrons to magnify small objects
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What is magnification
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the apparent increase in object size that is produced by a microscope
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What is visible light
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electromagnetic radiation that is detected by the human eye
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what is electromagnetic radiation
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energy in the form of electromagnetic waves given off by the sun and stars
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how do light microscopes magnify
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use curved glass lenses to magnify images formed by visible light rays
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what does the quality of a lens depend on
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how well it bends light rays to a common focal point
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what is resolution of a lens
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its ability to resolve two objects that are close together
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what is the numerical aperture of a lens
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constant that is written on the barrel of the lens. reflects the efficiency of a lens to collect light
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what is resolution distance or resolving power
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minimum distance two objects must be apart in order to be distinguished as 2 separate objects
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what is the contrast of a lens
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the difference in intensity between two objects or between an objects and its background
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what are bright field microscopes
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the produce magnified images in a field of bright white light, hence the name bright field microscope
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What are the two types of bright field microscopes
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simple and compound
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What are the two sets of lenses in the compound bright field microscope
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objective lens and ocular lens
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What are dark field microscopes
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use a special condenser that passes light rays which travel at a sharp angle to the specimens. Specimens are visible without staining and appear as bright objects in a dark field
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How do phase microscopes work
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they use a special condenser that passes light waves only in the same phase. this produces sharp images of cells and their internal structures without having to stain them.
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What are the two types of phase microscopes
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Phase contrast- produces contrast differences in images
Differential interference-produces a 3D appearance |
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how do fluorescent microscopes work
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use special filters and illuminators. Microbes are stained with fluorescent dye
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what is immunofluorescence
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a common application of fluorescent microscopy
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how does a confocal microscope work
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use a laser light, a fluorescent dye and a computer to produce a series of sharp, 1 microliter thick, single plane images of a specimen. Images are constructed into 3D image
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How do electron microscopes work
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they use a beam of electrons to form images instead of visible light rays
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What are the two types of electron microscopes
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Scanning and transmission. Scanning gives 3D views of the surface of microbes. Transmission are used to view internal sub cellular structures in thin sections of microbes and tissues
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Hw does probe microscope work
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Uses tiny pointed tungsten probes and magnify up to 100,000,000x
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What are the two types of probe microscopes
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Scanning tunneling microscopes- measure the flow of electrons between the probes tip and the specimens surface
Atomic force- revels detail at atomic level |
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When is a wet mount used
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when living microbes are going to be examined. usually in dark field or phase contrast microscopes
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when is a smear used
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when the microbes are going to be stained in a light microscope
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What is a wet mount
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liquid suspension of microbes under a cover slip on a class slide
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What is the difference between brownian motion and motile.
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Motile microbes swim vigorously in a straight line. Brownian motion is random motion or tumbling caused by bombardment of water molecules
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what are the types of staining
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simple, negative, differential, special, electron microscope
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what are simple stains
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aqueous or alcohol solution of a single basic dye
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what are negative stains
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consist of acidic dyes or black particles. they stain the background not the microbe
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what are differential stains
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react differently with different groups of bacteria. provide a quick means of distinguishing these bacterial groups from each other.
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What are the types of differential stains
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gram stain, acid fast stain, endospore stain
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What are the four life processes
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replicate, grow, metabolize and respond to the environment
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What are the 3 basic shapes of prokaryotic cells
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cocci-round
bacilli-rod spiral-twisted |
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What kind of ends can bacilli
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square rounded ellipsoid or spindle shaped ends
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what species of bacilli form V,Y and palisade shapes
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Corynebacterium
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What type of bacilli form short rod and Y shapes
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Actinomyces
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what type of bacilli lack cell walls and are pleomorphic
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Mycoplasma
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What are the three groups of spiral shaped bacteria
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vibros-curved comma shaped bacteria
Spirilla- rigid spiral shaped spirochetes-flexible corkscrew shaped bactria |
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what are the major external structures of prokaryotic cells
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glycocalyx, flagella, fimbriae and sex pili, the cell wall
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What is the glycocalyx of prokaryotes and what is it made up of
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thick gelatinous polymer that covers or surrounds the outside of the cell. usually polysaccharides but can also be proteoglycans or proteins
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what are the two types of glycocalyxes
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capsules-thick discrete gel that completely surounds a microbial cell and cannot be easily separated from the cell
Slime layers-form loosely around a cell and can easily be washed away from the cell |
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What do glycocalyx do
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protect microbial cells from drying and are important virulence factors for many disease and producing bacteria
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why are capsules and slime layers virulence factors for pathogenic microbes
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They interfere with their phagocytosis by host phagocytes, prevent their desiccation (drying) which enhances their survival outside of hosts, facilitating transmission to new hosts, and they mediate the attachment of encapsulated pathogens to host structures and implanted devices in skin.
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What type of bacteria produce a dlucan slime layr and attaches to teeth, where it causes dental caries
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Streptococcus mutans
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what are three major parts of plagella
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a long filament, a hook and a basal body
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What are the types of bacteria with flagellum
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Monotrichous-bacteria with a single flagellum
lophotrichous- bacteria with two or more flagella at one end of the cell amphitrichous-bacteria with on or more flagella at each end of the cell peritrichous- bacteria with multiple flagella that are distributed all around the surface of the cell |
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what is taxis
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motile bacteria have the ability to move toward or away from stimulants
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What is phototaxis
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movement toward light
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what is chemotaxis
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movement toward higher concentrations of a chemoattractant or away form a repellent
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What are axial filaments
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coney motility to spirochetes
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What are pili
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structures that participate in bacterial conjugation
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What are fimbriae
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sitcky, non-motile, bristle-like filament on the surface of bacterial cells. they can mediate the attachment of a bacterial cell to another cell
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what are adhesins
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substances that mediate the attachment of one cell to another cell or surface. Adhesins play an essential role in the formation of biofilms and in the colonization of host surfaces
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What are lectins
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substances that bind to a specific sugar on a glycoprotein
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what is conjugation
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when sex pili allow gram negative bacteria to transfer DNA form one cell to another in a process
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What is the difference between gram positive and negative bacteria
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Gram positive cell walls are composed of a single, thick layer of peptidoglycan and gram negative is composed of two layers, and outer membrane layer and a thin inner layer of peptidoglycan
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What is peptidoglycan
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a large highly crosslinked polymer in bacterial cell walls that surrounds the bacterial cell, maintains its shape and structural rigidity and protects it form osmotic lysis
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What is peptidoglycan made up of
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long polysaccharide chains crosslinked by peptide bridges
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What are teichoic acids
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found only in gram positive bacteria and are essential for their survival though their exact function is unknown
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Polysaccharides in gram-positive bacteria can be what?
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teichoic acids, teichuronic acids, neutral polysaccharides or acidic polysaccharides
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What are the types of teichoic acids
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Ribitol teichoic acids- covalently linked to the hydroxyl group on carbon-6 of N-Ac-muramic acid residues in peptidoglycan
Glycerol teichoic acids-covalently linked to a glycolipid in the cytoplasmic membrane and are called lipoteichoic acids |
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What is the outer layer of gram negative cell walls made up of
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lipopolysaccharide, proteins and phospholipids
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What is the periplasmic space
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in gram negative cell walls the space between the cytoplasmic membrane and the outer membrane is called the periplasmic space
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why are gram negative cells more flexible than gram positive
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they have less peptidoglycan
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What are lipopolysaccharides
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unique complex glycolipids that contain three distinct covalently linked parts Lipid A, the core polysaccharide, the O-specific polysaccharide
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What is lipid A
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large complex, unusual glycolipid. large size and numerous saturated fatty acid chains in lipid A make the outer membrane of gram negative bacteria more rigid than a typical phospholipid membrane
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What does the core polysaccharide do
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links lipid A to the O-specific polysaccharide chain. Contains 8 carbon sugar and 7 carbon sugar
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What is the major surface antigen of gram negative bacteria
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O-specific polysaccharide chain
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What is septicemia
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when endotoxin poisoning occurs when gram negative bacteria enter the bloodstream and multiply in it
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What is a pyrogen
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substances that cause fever
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What is a porin
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major protein in the outer membrane is a channel forming protein. They allow low molecular weight hydrophilic nutrients to pass through the outer membrane
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What is the function of a cytoplasmic membrane
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A selective permeability barrier and controls the passage of materials into and out of the cell
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The cytoplasmic membrane is made up of lipid and proteins. What are the lipid components
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Phosphoglycerides, sphingolipids, sterols. It functions as the permeability barrier
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What is the function of the protein components in the cytoplasmic membrane
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They endow the membrane with selective permeability to hydrophilic compounds
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What are leaflets
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The individual layers in a lipid bilayer
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What do bacteria form their plasma membrane with
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Phosphoglycerides
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What do archea for their cytoplasmic membrane with
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phosphoglycerol diethers or diphosphoglycerol tetraethers that contain branched hydrocarbon side chains
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What do Eukaryotic organisms form their plasma membrane with
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Phosphoglycerides, sphingolipids and sterols
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What is the difference between Eukaryotic and prokaryotic plasma membranes
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Prodaryotes do not have internal membrane bound organelles so their plasma membrane carries out many of the function associated with these eukaryotic structures
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Cells actively maintain an electrical gradient of about what across their cytoplasmic membrane
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-70mV
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What is the electrochemical gradient
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combined chemical and electrical gradients
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What do cells use electrochemical gradient energy for?
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To transport substances across their cytoplasmic membrane
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What are the two types of transport
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Active and passive
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What are the three types of passive transport
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simple diffusion, facilitated diffusion and osmosis
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What is simple diffusion
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movement of molecules across a membrane unaided form a higher to a lower concentration until chemical equilibrium is reached (oxygen, co2, alcohol and short chain fatty acids)
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What is facilitated diffusion
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the movement of molecules across a membrane from a higher to a lower concentration through non-specific ion channels or by specific transport proteins
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What is osmosis
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the movement of water molecules across a semi-permeable membrane from a solution of higher water concentration to one with a lower water concentration
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When does osmosis occur
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when dissolved solutes cannot cross a semipermeable membrane but water molecules can and the solutions on the two sides of a semipermeable membrane differ in solute concentration and therefore also differ in water concentration
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What is osmotic pressure
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the hydrostatic pressure required to stop the net flow of water across a semi-permeable membrane that separates two solutions with different solute concentrations.
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What are isotonic, hypotonic and hypertonic solutions
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Isotonic has the same solute and water concentrations
Hypotonic solutions have more water and less solute Hypertonic solutions have more solute and less water |
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What are the three types of active transport
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active transport, secondary active transport and group translocation
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What is active transport
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process that uses ATP pump to move substances across the cytoplasmic membrane against their electrochemical gradient
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What is secondary active transport
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use antiporters and symporters to move substances across the cytoplasmic membrane
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What is group translocation
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accumulates a substrate against its concentration gradient by phosphorylating it during its transport into a cell
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What is the genetic material of most prokaryotic cells
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a single circular molecule of DNA that is in direct contact with the cytoplasm called the nucleoid
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What are plasmids
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extra-chromosomal circular molecules of DNA that are readily transferred to other prokaryotes
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What do ribosomes do
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synthesize proteins
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What are the difference between prokaryotic ribosomes and eukaryotic ribosomes
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Size. the prokaryotic ribosomes are 70 S and he eukaryotic ribosomes are 80 S.
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What are prokaryotic inclusions
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large granules or storage deposits in the cytoplasm of prokaryotic cells. they can serve as a food or energy reserve
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What are endospores
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highly resistant resting structures that are formed by some bacteria for survival during adverse conditions. they are resistant to killing by chemical and physical agents that readily kill growing microbes
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The process of endospore formation is called what
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sporulation
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Why are endospores highly resistant to killing
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they contain little water or cytoplasm, multiple coats, and dipicolinic acid
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What is germination
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When endospores return to a growing state
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What are the two medically important genera of endospore-forming bacteria
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Clostridium-produce potent exotoxins and cause several life threatening infectious diseases including tetanus, botulism, and gas gangrene
Baccillus-anthrax and food poisoning |
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What are the external structures of Eukaryotic cells
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a glycocalyx, flagella or cilia, cell wall
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What is the glycocalyx of Eukaryotic cells
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glycocalyx protects animal and protozoan cells because they do not have cell walls. They hold the cells together, protect against dehydration and help with cell communication
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What is the pellicle
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the glycocalyx of protozoa
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What are eukaryotic cell walls composed of
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polysaccharides
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What process can eukaryotic cells do the prokaryotic cells cant that moves materials across their plasma membrane?
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Endocytosis (phagocytosis, pinocytosis) and exocytosis
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What is phagocytosis
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the ingestion of particulate materials by a cell
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What is pincocytosis
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the ingestion of liquid materials by a cell
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what is receptor mediated endocytosis
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the ingestion of molecules that have bound to a membrane receptor
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What are the functions of the eukaryotic cytoskeleton and what is it made up of
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It is a large complex network of protein filaments and microtubules. It anchors organelles, It enables cytoplasmic streaming and the movement of organelles in the cytoplasm, it enables a cell to contract, it moves the cell membrane during endocytosis and it provides shape to the cell
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What are the three major types of protein structures that make up the eukaryotic cytoskeleton
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Microtubules, microfilaments, intermediate filaments
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What do centrioles do
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participate in mitosis and cytokinesis
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What are proteosomes
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protein organelles in the cytoplasm of animal cells that degrade proteins into peptides
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What does the nucleus do
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contains most of the cells genetic information
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What do pores in the nucleus do
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control the import and export of substances through the membrane
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Where does RNA synthesis occur
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In the nucleoli in the nucleus
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How does nuclear division in eukaryotic cells occur
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mitosis and meiosis
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What is the endoplasmic reticulum
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a large flat membranous network that has a rough and smooth
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What does the smooth er do
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synthesizes lipids and also functions in the formation of transport vesicles
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What does the rough er do
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site of synthesis of proteins that are going to be transported to other sites in the cell or secreted form the cell. Have ribosomes on them
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What does the golgi complex do
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It is a complex of smooth, flat, hollow membranous sacs in eukaryotic cytoplasm. Receives, sorts and packages proteins and lipids from the endoplasmic reticulum into secretory vesicles for transport to other sites in the cell or export from the cell
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What peroxisomes
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decompose poisonous metabolic wastes and degrade fatty acids
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What do mitochondria do
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cary out the krebs cycle and oxidative phosphorylation
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What physical factors affect microbial growth
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Temperature, pH, osmolarity, hydrostatic pressure
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What are the 4 major groups of microbes that are based upon the effect of temperature on their growth
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Psychrophiles, Mesophiles, Thermophiles, Hyperthermophiles
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What are psycotrophs
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microbes that grow between 0-30 degrees that spoil refrigerated foods
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What is the maximum growth temperature of a microbe determined by
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the stability of its enzymes to heat
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Bacteria row rapidly at what temperatures
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16-50 C
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Waht is the optimal pH level for most bacteria to grow
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7.0 to 7.4
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How do many bacteria grow
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by fermenting sugars to acids
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what is hypotonic lysis
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if cells lacking a cell wall are placed in a medium with very low osmolarity they burst from osmotic pressure
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what are halophiles
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microbes that have adapted to growth in high salt environments
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what are barophiles
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organisms that live in deep ocean basins under extreme pressure
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how do most cells obtain the H atoms they need for synthesis
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From their carbon source or form H2O
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how do cells obtain most of the oxygen they need for the synthesis of cell constituents
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from co2 or the organic molecules they use as a carbon source
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what are obligate anaerobes
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microbial cells that oxygen is a deadly poison
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What are organic growth factors
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compounds that are essential for the growth that an organism is unable to synthesize
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why are siderophores important virulence factors for pathogenic bacteria
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they allow them to take iron away form host proteins
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What is the cultivation of microorganisms
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microbial culture
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What is a culture medium
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any nutrient material used to grow microbes in a laboratory
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What fastidious
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organisms that require special growth factors in order to be cultured
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What is agar
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a complex polysaccharide found in marine algae and seaweed. It is an ideal solidifying agent for microbial media
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What is an agar slant
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if a liquid agar medium is allowed to solidify in a test tube at an angle by tilting the tube
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What is a chemically defined culture medium
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one whose exact chemical composition is known
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what is a complex culture medium
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one whose exact chemical composition is not known
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What are reducing media
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cultures that contain a reducing agent that chemically reacts with oxygen and removes it from the medium
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What is the most widely used reducing medium
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Fluid Thioglycollate Medium
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Removal of oxygen from a medium allows what to grow in the medium
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obligate anaerobes
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What is the GasPak Jar System
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A sealable jar in which O2 is removed chemically by reaction with H2 in the presence of a palladium catalyst
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What are anaerobic chambers
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large plastic chambers that are filled with with oxygen-free gas
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What are roll tubes
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individual culture tubes that are filled with oxygen free gas and tightly stoppered
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What are selective media cultures
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contain ingredients which inhibit the growth of unwanted bacteria but allow the desired microbe to grow
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What are differential media cultures
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They permit colonies of a sought microbe to be differentiated from colonies of other microbes growing on the same plate, by showing a visible difference in color, size and precipitate formation
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What is Chromagar Orientation
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a differential medium that allows rapid identification of the bacteria that most commonly cause urinary tract infections
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Why are selective and differential media widely used
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they allow rapid detection and isolation of a sought microbe in a sample even if the microbe is only a small percentage of the total flora in the sample
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What are transport media cultures
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contain minimal nutrients and are designed to keep the microbes in a clinical sample alive without promoting their growth while the sample is being transported to a lab for culture
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What microbes require special culture conditions in order to be grown
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culture n living animals, culture in animal cells, culture in an elevated CO2 atmosphere, and enrichment culture
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Which microbe causes syphilis
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Treponema palladium
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What are capnophilic bacteria
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bacteria that grow better in an atmosphere
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What are enrichment cultures
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select for a sought microbe by using a culture medium that will promote its growth
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what are some methods of isolating pure cultures of a microorganism
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steak plate technique, dilution plating
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How can water, soil and food be tested for microbes
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by mixing a small sample of the source material into sterile saline or media and doing streak test or dilution plating analysis of the saline sample
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how can air and dilute water samples be tested for microbes
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by passing them through a .2microliter filter
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What are antagonistic, synergistic and symbiotic relationships
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antagonistic- one organism harms or kills another (viruses)
synergistic-organisms receive benefits that exceed those which would result if they grew by themselves symbiotic- organisms adapt to living together |
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why is it difficult to treat diseases caused by biofilms
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they are resistant to antimicrobial chemicals, antibiotics and host immune responses
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what is quorum sensing
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microbes that form biofilms have a chemical signaling mechanism called quorum sensing that senses growth density
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what is binary fission
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how bacterial cells reproduce
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what is generation time
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the time required for the number of cells in a microbial population to double under optimal growth conditions
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what are the generation time range for bacteria
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8 minutes to 20 hours. Most re between 20 and 120 minutes
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What is a bacterial growth curve
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a plot of bacterial growth versus time
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what are the growth phases in the bacterial growth curves
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lag phase, log phase, stationary phase and death phase
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What happens in the lag phase of the bacterial growth curve
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The first step where bacteria do not begin multiplying immediately upon inoculation into a fresh culture medium
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What can affect the length of the lag phase in the bacterial growth curve
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Properties inherent in the microbe being grown, the age and size of the inoculum, nutrients and pH f the new and old medium
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With is the log growth phase of the bacterial growth curve
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the second stage which all of the bacterial cells are multiplying and the cell number doubles with each succeeding generation
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what is the stationary phase bacterial growth curve
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where the number of cells dying is equal to the number of cells that are being formed
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What is synchronous growth
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that all of the cells in a bacterial population are simultaneously in the same stage of the division process
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What does continuous growth mean
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all of the cells in a bacterial population are in the logarithmic growth phase
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What does it mean to get a direct method for measuring the growth of microbe
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determine the number of cells in a population
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What does in mean to have indirect methods for measuring the growth of microbes
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determine the mass of a population which is proportional to the number of cells in the population
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What is a standard (viable) plate count
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direct method and most frequently used method for measuring the number of cells in a bacterial population. measure only viable cells
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What are membrane filtration counts
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Used to determine the number of microbial cells in water or air samples that contain only a few microbes per volume
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What are microscopic counts
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performed with a special ruled glass slide called Petroff-Houser counter that allows a known sample volume to enter a ruled 1 mm area. Measure viable and dead cells
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What are electronic particle counts
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used to count the number of microbial cells in a sample but the results are usually not very reliable because of the small size and variable shape of prokaryotic cells. They give reliable results with larger cells.
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What is the most probable number method
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uses statistics to estimate the number of fecal microbes in a water sample
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What is turbidity
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the simplest and most frequently used indirect method for determining bacterial growth in liquid cultures
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what are the indirect methods of measuring the growth of populations
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Turbidity, dry weight, measuring a metabolic product
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what are the properties of microorganisms primarily determined by
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their genetic makeup
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where is genetic information cells stored
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genes and is transmitted form parent to offspring during cell division
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what is heredity
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the transmission of characteristics form parents to offspring
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what is genetics
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the study of heredity. includes the study of genes and their physical structure, how genes carry their genetic information
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what is a genome
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genetic information in a cell or virus
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what is a gene
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a specific segment of DNA or RNA that codes for a functional product such as a protein or RNA molecule
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What is DNA composed of
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2 complementary polynucleotide chains that twist around each other in a right-handed double helix
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what are the nucleotides in DNA composed of
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a cyclic nitrogenous base, a 5 carbon sugar, a phosphate group
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What are the 4 cyclic nitrogenous bases present in DNA
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adenine, thymine, guanine and cytosine. RNA has uracil in place of thymine
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How are the nucleotides in DNA and RNA linked
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covalently linked via phosphodiester bridges
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What do prokaryotic genomes consist of
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1 chromosome and sometimes 1 or more plasmid
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How are plasmids classified
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Fertility-carry genes for sex pili and enzymes that carry out conjugation
Resistance-plasmids that carry genes the confer resistance to antibiotics or cellular toxins Bacteriocin-carry genes for toxins that kill other bacteria Virulence-carry genes for virulence factors Dissimilation-carry genes for degradative enzymes |
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What are the difference between eukaryotic genomes and prokaryotic genomes
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eukaryotes usually have more than 1 chromosome prokaryotes usually don't
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what are eukaryotic chromosomes composed of
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linear DNA molecules and basic proteins called histones
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what does DNA replication require
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energy and monomeric building blocks of each of the four deoxyribonucleotides in DNA
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What does DNA polymerase do
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during DNA synthesis, nucleotides are added to the 3 end of the nucleotide stand being synthesized by an enzyme called DNA polymerase
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Where does the Dna replication begin
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the orgin
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what is the DNA strand called that is synthesized continuously as a single long chain of nucleotides because DNA polymerase moves towards the replication fork as it adds nucleotides to the 3 end
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the leading strand
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why do cells methyate DNA
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to regulate gene expression, to mark the initiation site for DNA synthesis, to mark their own DNA with a uniques CH3 pattern to distinguish it from foreign DNA, to distinguish older DNA from newly formed ones so that errors in new stands can be repaired
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what is the phenotype of an organism
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its physical features and functional traits
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What is transcription
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the synthesis of a complementary single stranded RNA copy of a gene
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What is translation
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when ribosomes translate the mRNA nucleotide sequences into the protein product of the gene
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What does messenger RNA do
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carry genetic info from DNA to ribosomes
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what does ribosomal RNA do
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key structural components of ribosomes, the organelles that synthesize proteins
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What does Transfer RNA do
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molecules deliver amino acids to ribosomes
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What are the three steps of transciption
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initiation of transcription
elongation of the RNA transcript Termination of transcription |
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What is the enzyme that synthesizes RNA from DNA
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RNA polymerase
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What does translation require
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ribosomes, mRNA, amino acid charged tRNA molecules, GTP and several protein factors
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Individual amino acids in proteins are dictated by 3 base RNA segments called
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codons
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What are introns and exons
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introns are regions of non encoding DNA and exons are regions of coding DNA that are in eukaryotic cells
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what is a mutation
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a change in a gene's nitrogenous base sequence
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mutations that alter a genes product can be what?
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neutral-if the change occurs in a non essential portion of the protein product
deleterious-change inactivates the protein product beneficial-altered protein product works better |
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What is a point mutation
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a change in a single nitrogenous base in DNA
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what is a frameshift mutation
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mutations in which the insertion or deletion of 1 or more nitrogenous base in DNA causes a shift in the coding sequence for the rest of the gene
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what are mutagens
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substances in he environment that increase the mutation rate in DNA
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what are some example of mutagens
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many chemicals and radiation such as ionizing radiation and low wavelength ultraviolet light
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what are ionizing radiation mutagens
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x-rays, gamma rays and high speed subatomic particles. causes hydroxide ions in cytoplasm of cells to lose electrons and form highly reactive hydroxyl free radicals
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what is mutagenic low wavelength ultraviolet light
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electromagnetic energy that causes adjacent pyrimidine bases in DNA to bond together
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what are nucleotide analogues
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chemicals that are structurally similar to the nucleotide bases in DNA
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what are frameshift mutagens
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chemicals that insert themselves between the paired nucleotide bases in DNA
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what are some ways to repair DNA
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Light and Dark repair enzymes for UV light induced pryimidine dimers. Base excision repair, mismatch repair enzymes and the SOS response.
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what is the base excision DNA repair
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enzymes cut out a small nucleotide segment containing nucleotide and then DNA polymerase repairs the gap
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what is mismatch DNA repair
|
enzymes remove the incorrect nucleotide and DNA polymerase and ligase repair the gap
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what are wild type cells
|
cell phenotypes that are commonly found in nature
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what are mutants
|
descendents of a cell that does not successfully repair a mutation
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what are ways to test for mutants
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positive selection and negative selection
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what is positive selection
|
directly selects mutant cells and rejects non mutated cells
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what is negative selection
|
it is done by replicate plating. used to isolate an auxotroph
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What is an auxotroph
|
a mutant that has a nutritional requirement not seen in the parent wild type cell
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What is the Ames test
|
a rapid inexpensive test that utilizes a histidine auxotroph of Salmonella Typhimurium to identify chemicals that are mutagens and possible chemical carcinogens
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what is genetic recombination
|
the exchange of genes between 2 DNA molecules to form new combinations of genes on a chromosome
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what is the difference in genetic recombination in prokaryotic and eukaryotic cells
|
eukaryotic uses crossing over, prokaryotes use horizontal gene transfer
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what is horizontal gene transfer
|
transfer of DNA between two different cells
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what are some ways horizontal gene transfer occurs
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transformation, conjugation and transduction
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what is transformation
|
the transfer of genes from 1 cell to another as naked DNA in solution
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