Term
| LUCA (Last Universal Common ancestor) |
|
Definition
the common ancestral cell from which all cells descended
Ex. Bed bugs |
|
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Term
|
Definition
The use of microorganisms to remove or detoxify toxic or unwanted chemicals in an environment
Ex. To clean up oil spills, bacteria are introduced to the area of the spill where they break down the hydrocarbons of the oil into carbon dioxide |
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Term
|
Definition
The aggregated mass of DNA that makes up the chromosomes of prokaryotic cells
Ex. prokaryotic cell |
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Term
|
Definition
A differentiated cell formed within the cells of certain gram + bacteria that is extremely resistant to heat as well as to other harmful agents.
Ex. Bacillus |
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|
Term
| TEM (Transmission electron microscopy) |
|
Definition
| is a microscopy technique in which a beam of electrons is transmitted through an ultra-thin specimen, interacting with the specimen as it passes through. |
|
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Term
|
Definition
The rigid layer of the cell walls of Bacteria, a thin sheet composed of N-acetylglucosamine, N-acetylmuramic acid, and a few amino acids
-Used to determine if a gram stain is positive or negative |
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|
Term
|
Definition
Phylogenetically related prokaryotes distinct from Bacteria.
Ex. Halophiles |
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Term
|
Definition
Prokaryotic oxygenic phototrophs containing chlorophyll a and phycobilins
ex. ALS cluster |
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Term
|
Definition
| An energy dependent transport system in which the substance transported is chemically modified during the process of being transported by a series of proteins. |
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Term
|
Definition
| is an integral membrane protein that is involved in movement of two or more different molecules or ions across a phospholipid membrane such as the plasma membrane in the same direction, and is, therefore, a type of cotransporter. |
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Term
|
Definition
Complex lipid structure containing unusual sugars and fatty acids found in most gram negative bacteria and constituting the chemical structure of the outer membrane
ex. endotoxin |
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Term
|
Definition
| The area between the cytoplasmic membrane and the outer membrane in gram-negative bacteria. |
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Term
|
Definition
| Short, filamentous structure on a bacterial cell; although flagella-like in structure, it is generally present in many copies and not involved in motility. |
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|
Term
| Peritrichous Flagellation |
|
Definition
| In flagellar arrangements, having flagella attached to many places on the cell surface |
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Term
|
Definition
| A continuous culture device controlled by the concentration of limiting nutrient and dilution rate |
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Term
|
Definition
| The period after inoculation of a culture before growth begins. |
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Term
|
Definition
| The time required for a cell population to double. Also called doubling time. |
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|
Term
The structure that confers structural strength on the cell is known as the:
cytoplasm.
cell wall.
cytoplasmic membrane.
ribosome. |
|
Definition
|
|
Term
In what/which domain(s) of life is/are microorganisms represented?
Archaea
Bacteria
Archaea, Bacteria, and Eukarya
Eukarya |
|
Definition
| Archaea, Bacteria, and Eukarya |
|
|
Term
The process whereby microorganisms are used to help clean up pollution created by human activities is known as
bioengineering.
biodegradation.
bioaugmentation.
bioremediation. |
|
Definition
|
|
Term
The theory of spontaneous generation was refuted by the work of
Robert Koch.
Robert Hooke.
Louis Pasteur.
Antoni van Leeuwenhoek. |
|
Definition
|
|
Term
Developments in the fields of immunology and medical microbiology were practical extensions of the work of
Sergei Winogradsky.
Robert Koch.
Antoni van Leeuwenhoek.
Joseph Lister. |
|
Definition
|
|
Term
| The discipline of microbiology is intimately associated with biochemistry and genetics, because cells are both biochemical catalysts and genetic coding devices. T/F |
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Definition
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Term
You are given an electron micrograph of a bacterial cell. In the micrograph you can clearly see three thin layers of different densities surrounding the cell. Based on the micrograph, you can infer that this cell is ________ and would appear ________ after application of the Gram stain procedure.
gram-negative / pink
gram-negative / purple
gram-positive / pink
gram-positive / purple |
|
Definition
|
|
Term
| Teichoic acids are commonly found in gram-negative cell walls. t/f |
|
Definition
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|
Term
Which of the following types of microscopy can be used with live cells?
scanning electron microscopy
transmission electron microscopy
bright-field microscopy
phase-contrast microscopy |
|
Definition
| phase-contrast microscopy |
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|
Term
Compared to Eukaryotes, Bacteria and Archaea have ________ surface-to-volume ratios, causing ________ nutrient exchange and growth rates.
higher / lower
lower / higher
lower / lower
higher / higher |
|
Definition
|
|
Term
Which is/are a function(s) of the cytoplasmic membrane in prokaryotes?
*It functions as a permeability barrier.
*It serves as a permeability barrier, a docking station for proteins involved in bioenergetics reactions and transport, and a site for energy conservation.
*It is an anchor for many proteins involved in bioenergetic reactions and transport.
*It is a major site of energy conservation. |
|
Definition
| It serves as a permeability barrier, a docking station for proteins involved in bioenergetics reactions and transport, and a site for energy conservation. |
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|
Term
The prokaryotic transport system that involves a substrate-binding protein, a membrane-integrated transporter, and an ATP-hydrolyzing protein is
group translocation.
simple transport.
symport.
the ABC transport system. |
|
Definition
| the ABC transport system. |
|
|
Term
The lipopolysaccharide (LPS) layer is found ONLY in the cell walls of
Eukarya.
gram-negative Bacteria.
gram-positive Bacteria.
Archaea. |
|
Definition
|
|
Term
Which of the following statements is TRUE?
*Pili serve as receptors and facilitate genetic exchange between prokaryotic cells.
*Fimbriae enable cells to stick to surfaces.
*Fimbriae are generally shorter and more numerous than flagella.
*Fimbriae are usually shorter than flagella and enable cells to adhere to surfaces, whereas pili are involved in genetic exchange. |
|
Definition
| Fimbriae are usually shorter than flagella and enable cells to adhere to surfaces, whereas pili are involved in genetic exchange. |
|
|
Term
Which of the following statements is FALSE?
*The hook is the wider region at the base of the flagellum.
*Flagellar rotation generates ATP.
*A flagellar protein subunit is flagellin.
*In flagellar motion, the basal body acts as a motor. |
|
Definition
| Flagellar rotation generates ATP. |
|
|
Term
Aseptic technique refers to
*a series of practices to avoid contamination.
*cleanliness in the laboratory.
*the autoclave and other sterilizing procedures.
*the microbial inoculum placed into a test tube or onto a Petri plate. |
|
Definition
| a series of practices to avoid contamination. |
|
|
Term
The process by which two cells arise from one is known as
meiosis.
conjugation.
binary fission.
mitosis. |
|
Definition
|
|
Term
The partition that is a result of the inward growth of the cytoplasmic membrane and cell wall from opposing directions is known as the
colony.
septum.
divisome.
autolysin. |
|
Definition
|
|
Term
Microbial growth is generally described as the increased number of cells rather than the expanding size of an individual microbial cell.
True
False |
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Definition
|
|
Term
In a chemostat, growth rate and growth yield can be controlled independently.
True
False |
|
Definition
|
|
Term
Specify which of the following is a major microbial ecosystem.
fungi
the atmosphere
plants and animals
sunlight |
|
Definition
|
|
Term
Which statement best illustrates the importance of a high surface-to-volume ratio that is found in microorganisms?
A. If a cell has a high surface-to-volume ratio, there will NOT be enough surface area to get the needed nutrients in to support cellular metabolism and the accumulated waste out.
B. If a cell has a high surface-to-volume ratio, the volume of the cell will be much larger than the surface area. There would NOT be enough surface area to get the needed nutrients in and the accumulated waste out.
C. If a cell has a high surface-to-volume ratio, the volume of the cell will be much larger than the surface area. There would be enough surface area to get the needed nutrients in and the accumulated waste out.
D. If a cell has a high surface-to-volume ratio, there will be enough surface area to get the needed nutrients in to support cellular metabolism and the accumulated waste out. |
|
Definition
| If a cell has a high surface-to-volume ratio, there will be enough surface area to get the needed nutrients in to support cellular metabolism and the accumulated waste out. |
|
|
Term
If an E. coli cell has a surface area-to-volume (S/V) ratio of 4.5, and a Pelagibacter ubique has an S/V ratio of 22, which cell will be able to exchange nutrients and wastes with the environment more efficiently?
E. coli, because its cells are larger
Pelagibacter ubique, because its cells are smaller
E. coli, because its cells are smaller
Pelagibacter ubique, because its cells are larger |
|
Definition
| Pelagibacter ubique, because its cells are smaller |
|
|
Term
A student observed a stained specimen of bacteria using bright-field microscopy. At 100x magnification, there appeared to be only one cell in the field of view, but at 1000x it was clear that there were two cells close together. The ability to distinguish these two cells as separate entities is called __________.
cell division
resolution
magnification
wavelength |
|
Definition
|
|
Term
Transport proteins can become saturated with solute, have high specificity for certain substances, undergo conformational (shape) changes, and are highly regulated by the cell. What other type of cellular proteins have these four general characteristics?
enzymes
porins
ribosomes
flagella |
|
Definition
|
|
Term
The enzyme lysozyme kills bacterial cells by cleaving the β-1,4-glycosidic bonds in the peptidoglycan. This leads to which of the following?
*out of control cell growth
*breaches of the cell wall and cell lysis due to osmotic swelling
*the inability of the cell to grow and divide
*lysis of the cell due to the same mechanism used by penicillin |
|
Definition
| breaches of the cell wall and cell lysis due to osmotic swelling |
|
|
Term
What is the biological function of endospores?
*They enable organisms to endure extremes of temperature, drying, and nutrient depletion.
*They are bacterial reproductive structures.
*Endospores can serve as reproductive structures, enable survival in harsh environments, and transport toxins.
*They transport toxins. |
|
Definition
| They enable organisms to endure extremes of temperature, drying, and nutrient depletion. |
|
|
Term
Based on the table of attributes given below, which of the following statements are FALSE about the two organisms?
Characteristic Bacterium A Bacterium B
Endospore formation yes no
Capsule no yes
Type IV pili yes no
Flagella no no
Morphology bacillus bacillus
*Bacterium A is more resistant to heat and ultraviolet light.
*Both bacteria may attach to surfaces.
*Bacterium B likely forms a slime layer better than Bacterium A.
*Bacterium B is likely to exhibit motility. |
|
Definition
| Bacterium B is likely to exhibit motility. |
|
|
Term
| Microbiology revolves around two themes: |
|
Definition
1. Understanding basic life processes
Microbes are excellent models for understanding cellular processes in unicellular and multicellular organisms
2. Applying that knowledge to the benefit of humans
Microbes play important roles in medicine, agriculture, and industry |
|
|
Term
| The importance of microorganisms |
|
Definition
Oldest form of life
Largest mass of living material on Earth
Carry out major processes for biogeochemical cycles
Can live in places unsuitable for other organisms
Other life forms require microbes to survive |
|
|
Term
| Microorganisms typically exist as ____ cells or as ___ ____ cells, each of which can carry out all life functions |
|
Definition
| single cells, loosely grouped |
|
|
Term
| Microbial cells: Prokaryotic cell structure |
|
Definition
| cell wall*, cytoplasmic membrane, cytoplasm, nucleoid, ribosomes |
|
|
Term
| Prokaryotic versus eukaryotic cells |
|
Definition
Prokaryotes
No membrane-enclosed organelles, no nucleus
Generally smaller than eukaryotic cells
Eukaryotes
DNA enclosed in a membrane-bound nucleus
Cells are generally larger and more complex
Contain organelles |
|
|
Term
| If Microbes are (primarily) single cell organisms and cells are the fundamental unit of life… |
|
Definition
| Then we can use the properties that define (are common to) all cells to define life. |
|
|
Term
| Characteristics of living cells |
|
Definition
-Metabolism
-Reproduction
-Differentiation
-Communication
-Movement
-Evolution |
|
|
Term
|
Definition
chemical transformation of nutrients
1. genetic
2. catalytic |
|
|
Term
|
Definition
| generation of two cells from one |
|
|
Term
|
Definition
| Synthesis of new substances or structures that modify the cells |
|
|
Term
|
Definition
| generation of, and response to, chemical signals |
|
|
Term
|
Definition
| via self-propulsion, many forms in microbes |
|
|
Term
|
Definition
| genetic changes in cells that are transferred to offspring |
|
|
Term
| Cells carry out chemical reactions |
|
Definition
Enzymes: protein catalysts of the cell that accelerate chemical reactions
Cells store and process information that is eventually passed on to offspring during reproduction through DNA (deoxyribonucleic acid) and evolution
Transcription: DNA produces RNA
Translation: RNA makes protein |
|
|
Term
| Life on Earth through the ages |
|
Definition
Earth is 4.6 billion years old
First cells appeared between 3.8 and 3.9 billion years ago
The atmosphere was anoxic until ~2 billion years ago
Metabolisms were exclusively anaerobic until evolution of oxygen-producing phototrophs
Life was exclusively microbial until ~1 billion years ago |
|
|
Term
| ___ microorganisms were the ancestors of multicellular organisms |
|
Definition
|
|
Term
| From the last universal common ancestor (LUCA), evolution proceeded to form two domains |
|
Definition
|
|
Term
| Archaea later diverged to form two domains |
|
Definition
|
|
Term
| Microbial diversity is staggering... |
|
Definition
Diverse habitats
Metabolic diversity
Genetic diversity
No. of taxa – in the order of millions |
|
|
Term
| Microorganisms exist in nature in... |
|
Definition
|
|
Term
| Populations of different species form... |
|
Definition
|
|
Term
| Populations interact with other populations in microbial communities in various ways, that effect the ___ and its ___ |
|
Definition
|
|
Term
| Diversity and abundances of microbes are controlled by ___ and ___ |
|
Definition
| resources (nutrients), environmental conditions (e.g., temp, pH, O2) |
|
|
Term
| The activities of microbial communities can greatly affect the chemical and physical properties of the ___ in which they exist |
|
Definition
ecosystems
-removal of nutrients
excretion of waste products |
|
|
Term
| Microorganisms can be both ___ and ___ to humans |
|
Definition
beneficial, harmful
Although we tend to emphasize harmful microorganisms (infectious disease agents), most microbes in nature are beneficial |
|
|
Term
| Beneficial aspects of microorganisms |
|
Definition
Production of oxygen by photosynthetic bacteria and algae
Decomposition of organic matter (C & nutrient cycling)
Economic importance |
|
|
Term
Many aspects of agriculture depend on microbial activities
Positive and Negative Impacts |
|
Definition
Positive impacts
Nitrogen-fixing bacteria
Cellulose-degrading microbes in the rumen
Regeneration of nutrients in soil and water
Negative impacts
Diseases in plants and animals |
|
|
Term
Microorganisms and food
Positive and Negative impacts |
|
Definition
Negative impacts
Microorganisms can cause food spoilage; for many foods, methods of preservation are needed
Positive impacts (Figure 1.11)
Microbial transformations (typically fermentations) yield
Dairy products (e.g., cheeses, yogurt, buttermilk)
Other food products (e.g., sauerkraut, pickles, leavened breads, beer) |
|
|
Term
| Microorganisms and their genetic resources |
|
Definition
Exploitation of microbes for production of antibiotics, enzymes, and various chemicals
Genetic engineering of microbes to generate products of value to humans, such as insulin (biotechnology) |
|
|
Term
| Microorganisms and the human gastrointestinal (GI) tract |
|
Definition
High numbers of microorganisms occur in colon and oral cavity (Figure 1.10)
-Positive impacts
*Synthesize vitamins and other nutrients
*Compete with pathogens for space and resources |
|
|
Term
| Microbiology began with the.. |
|
Definition
|
|
Term
|
Definition
the first to describe microbes
Illustrated the fruiting structures of molds |
|
|
Term
|
Definition
the first to describe bacteria
Further progress required development of more powerful microscopes |
|
|
Term
|
Definition
founded the field of bacterial classification and discovered bacterial endospores
discovered bacterial endospores (Bacillus) |
|
|
Term
|
Definition
Discovered that living organisms discriminate between optical isomers
Discovered that alcoholic fermentation was a biologically mediated process (originally thought to be purely chemical)
Disproved theory of spontaneous generation (Figure 1.17)
Led to the development of methods for controlling the growth of microorganisms (aseptic technique)
Developed vaccines for anthrax, fowl cholera, and rabies |
|
|
Term
|
Definition
1. The suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals
2. The suspected organism should be grown in pure culture
3. Cells from a pure culture of the suspected organism should cause disease in a healthy animal
4. The organism should be re-isolated and shown to be the same as the original |
|
|
Term
| Koch and the rise of pure cultures |
|
Definition
Discovered that using solid media provided a simple way to obtain pure cultures
Observed that masses of cells (called colonies) have different shapes, colors, and sizes. Began with potato slices, but eventually devised uniform and reproducible nutrient solutions solidified with gelatin and agar |
|
|
Term
| Koch’s Postulates are thought of as the ____ ______ in determining the cause of a disease |
|
Definition
|
|
Term
|
Definition
Developed enrichment culture technique
Microbes can be isolated from natural samples in a highly selective fashion by manipulating nutrient and incubation conditions |
|
|
Term
|
Definition
| Proposed the concept of Chemolithotrophy : oxidizing inorganic compounds to yield energy |
|
|
Term
| Major subdisciplines of applied microbiology |
|
Definition
Medical microbiology
Immunology
Agricultural microbiology |
|
|
Term
| Basic science subdisciplines in microbiology |
|
Definition
Microbial systematics
The science of grouping and classifying microorganisms
Microbial physiology
Study of the nutrients that microbes require for metabolism and growth and the products that microorganisms generate
Microbial ecology
Study of microbial diversity and activity in natural habitats
Microbial biochemistry
Study of microbial enzymes and chemical reactions
Bacterial genetics
Study of heredity and variation in bacteria
Virology
Study of viruses |
|
|
Term
|
Definition
Genomics: study of all of the genetic material
(DNA) in living cells
Transcriptomics: study of RNA patterns
Proteomics: study of all the proteins produced by cell(s)
Metabolomics: study of metabolic expression in cells |
|
|
Term
|
Definition
Bright-field microscopy
Phase-contrast microscopy
Dark-field microscopy
Fluorescence microscopy |
|
|
Term
|
Definition
| the ability to make an object larger |
|
|
Term
|
Definition
| the ability to distinguish two adjacent objects as separate and distinct |
|
|
Term
| Limit of resolution for a light microscope is about |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| Ability of the lenses to gather light (NA) |
|
Definition
Resolution is determined by the wavelength of light used and numerical aperture of lens
Limit of resolution for light microscope is about 0.2 μm |
|
|
Term
|
Definition
| Specimens are visualized because of differences in contrast (density) between specimen and surroundings |
|
|
Term
| Two sets of lenses form the image |
|
Definition
Objective lens and ocular lens
Magnification: the ability to make an object larger
Total magnification = objective magnification ✕ ocular magnification
Maximum magnification is ~2,000✕ |
|
|
Term
|
Definition
Enhances contrast for brightfield microscopy
colors the organism or background for better viewing |
|
|
Term
| Stains may be ____ or ____ |
|
Definition
basic (positive charge), acidic (negative charge)
basic dyes stain negatively charged bacteria
acidic dyes are repelled and stain background (negative staining) |
|
|
Term
| Phase-contrast microscopy |
|
Definition
Invented in 1936 by Frits Zernike
Phase ring amplifies differences in the refractive index of cell and surroundings
Improves the contrast of a sample without the use of a stain
Allows for the visualization of live samples
Resulting image is dark cells on a light background |
|
|
Term
|
Definition
Used to visualize specimens that fluoresce
Emit light of one color when illuminated with another color of light
Cells fluoresce naturally (autofluorescence) or after they have been stained with a fluorescent dye such as DAPI
Widely used in microbial ecology for enumerating bacteria in natural samples |
|
|
Term
| Differential interference contrast (DIC) microscopy |
|
Definition
Uses a polarizer to create two distinct beams of polarized light
Gives structures such as endospores, vacuoles, and granules a three-dimensional appearance
Structures not visible by bright-field microscopy are sometimes visible by DIC |
|
|
Term
| Confocal scanning laser microscopy (CSLM) |
|
Definition
Uses a computerized microscope coupled with a laser source to generate a three-dimensional image
Computer can focus the laser on single layers of the specimen
Different layers can then be compiled for a three-dimensional image
Resolution is 0.1 μm for CSLM |
|
|
Term
| Confocal Scanning Laser microscopy |
|
Definition
3D image via compilation of optical sections
Intense direct light source (laser)
Improves the resolution limit of light microsopy |
|
|
Term
| Electron microscopes use electrons instead of ___ to image cells and structures |
|
Definition
|
|
Term
| Two types of electron microscopes: |
|
Definition
Transmission electron microscopes (TEM)
Scanning electron microscopes (SEM) |
|
|
Term
| Transmission electron microscopy (TEM) (slide) |
|
Definition
Electromagnets function as lenses
System operates in a vacuum
High magnification and resolution (0.2 nm)
Enables visualization of structures at the molecular level
Specimen must be very thin (20–60 nm) and be stained |
|
|
Term
| Scanning electron microscopy (SEM) (slide) |
|
Definition
Specimen is coated with a thin film of heavy metal (e.g., gold)
An electron beam scans the object
Scattered electrons are collected by a detector, and an image is produced
Even very large specimens can be observed
Magnification range of 15✕–100,000✕ |
|
|
Term
|
Definition
Coccus (pl. cocci): spherical or ovoid
Rod: cylindrical shape
Spirillum: spiral shape |
|
|
Term
| Cells with unusual shapes |
|
Definition
| Spirochetes, appendaged bacteria, and filamentous bacteria |
|
|
Term
| Morphology typically does not predict ___, ___, ____ of a prokaryotic cell |
|
Definition
| physiology, ecology, phylogeny |
|
|
Term
| May be selective forces involved in setting the morphology |
|
Definition
Optimization for nutrient uptake (small cells and those with high surface-to-volume ratio)
Swimming motility in viscous environments or near surfaces (helical or spiral-shaped cells)
Gliding motility (filamentous bacteria) |
|
|
Term
| Size range for prokaryotes: |
|
Definition
0.2 µm to >700 µm in diameter
Most cultured rod-shaped bacteria are between 0.5 and 4.0 µm wide and < 15 µm long
Examples of very large prokaryotes
Epulopiscium fishelsoni
Thiomargarita namibiensis
Size range for eukaryotic cells: 10 to >200 µm in diameter |
|
|
Term
| Surface-to-volume ratios, growth rates, and evolution |
|
Definition
Advantages to being small
Small cells have more surface area relative to cell volume than large cells (i.e., higher S/V)
Support greater nutrient exchange per unit cell volume
Tend to grow faster than larger cells |
|
|
Term
| Lower limits of cell size |
|
Definition
Cellular organisms <0.15 µm in diameter are unlikely
Open oceans tend to contain small cells (0.2–0.4 µm in diameter)
row faster than larger cells |
|
|
Term
Cytoplasmic Membrane Structures
Selectively permeable barrier to large macromolecules but not to |
|
Definition
gases, water, small compounds (semipermeable)
Transport systems
Energy (proton gradient)
Receptors
Mostly lipids and proteins |
|
|
Term
|
Definition
General structure is phospholipid bilayer
Contain both hydrophobic and hydrophilic components
Can exist in many different chemical forms as a result of variation in the groups attached to the glycerol backbone
Fatty acids point inward to form hydrophobic environment; hydrophilic portions remain exposed to external environment or the cytoplasm |
|
|
Term
|
Definition
8–10 nm wide
Embedded proteins
Stabilized by hydrogen bonds and hydrophobic interactions
Mg2+ and Ca2+ help stabilize membrane by forming ionic bonds with negative charges on the phospholipids
Somewhat fluid
Integral membrane proteins
Firmly embedded in the membrane
Peripheral membrane proteins
One portion anchored in the membrane |
|
|
Term
|
Definition
Ether linkages in phospholipids of Archaea
Bacteria and Eukarya that have ester linkages in phospholipids
Archaeal lipids lack fatty acids; have isoprenes instead
Major lipids are glycerol diethers and tetraethers
Can exist as lipid monolayers, bilayers, or mixture |
|
|
Term
|
Definition
Polar and charged molecules must be transported
Transport proteins accumulate solutes against the concentration gradient |
|
|
Term
|
Definition
| Holds transport proteins in place |
|
|
Term
|
Definition
| Generation of proton motive force |
|
|
Term
|
Definition
Movement of molecules down a gradient of conc.
Diffusion directly through membrane
No energy expended
Water, lipid-soluble molecules, gases (O2, CO2) |
|
|
Term
| Carrier-mediated transport systems |
|
Definition
Show saturation effect
Highly specific |
|
|
Term
| Three major classes of transport systems in prokaryotes |
|
Definition
Simple transport
Group translocation
ABC system |
|
|
Term
| All require energy in some form, usually ____ or ____ |
|
Definition
| proton motive force or ATP |
|
|
Term
|
Definition
Driven by the energy
in the proton motive
force |
|
|
Term
|
Definition
Chemical modification
of the transported
substance driven by
phosphoenolpyruvate |
|
|
Term
|
Definition
Periplasmic binding
proteins are involved
and energy comes
from ATP. |
|
|
Term
| Three transport events are possible: |
|
Definition
uniport, symport, and antiport
Uniporters transport in one direction across the membrane
Symporters function as co-transporters
Antiporters transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction |
|
|
Term
| Simple transport: Lac permease of Escherichia coli |
|
Definition
Lactose is transported into E. coli by the simple transporter lac permease, a symporter
Activity of lac permease is energy-driven |
|
|
Term
| Chemical modification (by ____) of the transported molecule |
|
Definition
|
|
Term
| ATP-binding cassette (ABC transporter) |
|
Definition
Periplasmic binding proteins
Membrane-spanning proteins
ATP-hydrolyzing proteins |
|
|
Term
| Species of ___ separated into two groups based on Gram stain |
|
Definition
|
|
Term
| Gram-positives and gram-negatives have different ___ ___ _____ |
|
Definition
cell wall structure
Gram-negative cell wall
Two layers: LPS and peptidoglycan
Gram-positive cell wall
One layer: peptidoglycan |
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Term
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Definition
Rigid layer that provides strength to cell wall
Polysaccharide composed of:
N-acetylglucosamine and N-acetylmuramic acid
Amino acids
Lysine or diaminopimelic acid (DAP)
Cross-linked differently in gram-negative bacteria and gram-positive bacteria |
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Term
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Definition
Can contain up to 90% peptidoglycan
Common to have teichoic acids (acidic substances) embedded in their cell wall
Lipoteichoic acids: teichoic acids covalently bound to membrane lipids |
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Term
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Definition
Total cell wall contains ~10% peptidoglycan
Most of cell wall composed of outer membrane, aka lipopolysaccharide (LPS) layer
LPS consists of core polysaccharide and O-polysaccharide
LPS replaces most of phospholipids in outer half of outer membrane
Endotoxin: the toxic component of LPS |
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Term
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Definition
space located between cytoplasmic and outer membranes
~15 nm wide
Contents have gel-like consistency
Houses many proteins |
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Term
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Definition
channels for movement of hydrophilic
low-molecular-weight substances |
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Term
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Definition
No peptidoglycan
Typically no outer membrane
Pseudomurein
Polysaccharide similar to peptidoglycan
Composed of N-acetylglucosamine and N-acetylalosaminuronic acid
Found in cell walls of certain methanogenic Archaea
Cell walls of some Archaea lack pseudomurein |
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Term
| Archaeal Cell Walls: S-Layers |
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Definition
Most common cell wall type among Archaea
Consist of protein or glycoprotein
Paracrystalline structure |
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Term
| Capsules and slime layers |
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Definition
Polysaccharide layers
May be thick or thin, rigid or flexible
Assist in attachment to surfaces
Protect against phagocytosis
Resist desiccation |
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Term
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Definition
Filamentous protein structures
Enable organisms to stick to surfaces or form pellicles |
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Term
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Definition
Filamentous protein structures
Typically longer than fimbriae
Assist in surface attachment
Facilitate genetic exchange between cells (conjugation)
Type IV pili involved in twitching motility |
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Term
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Definition
Highly differentiated cells resistant to heat, harsh chemicals, and radiation
“Dormant” stage of bacterial life cycle (Figure 2.43)
Ideal for dispersal via wind, water, or animal gut
Present only in some gram-positive bacteria |
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Term
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Definition
Structurally complex
Contains dipicolinic acid
Enriched in Ca2+
Core contains small acid-soluble spore proteins (SASP) |
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Term
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Definition
structure that assists in swimming
Different arrangements: peritrichous, polar, lophotrichous
Helical in shape |
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Term
| Flagellar structure of Bacteria |
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Definition
Consists of several components
Filament composed of flagellin
Move by rotation |
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Term
| Flagella ___ or ___ rotational speed in relation to strength of the proton motive force |
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Definition
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Term
| Peritrichously flagellated cells move ___ in a ____ ___ |
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Definition
slowly, straight line
Polarly flagellated cells move more rapidly and typically spin around |
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Term
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Definition
Flagella-independent motility (Figure 2.56)
Slower and smoother than swimming
Movement typically occurs along long axis of cell
Requires surface contact
Mechanisms
Excretion of polysaccharide slime
Type IV pili
Gliding-specific proteins |
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Term
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Definition
directed movement in response to chemical or physical gradients
Chemotaxis: response to chemicals
Phototaxis: response to light
Aerotaxis: response to oxygen
Osmotaxis: response to ionic strength
Hydrotaxis: response to water |
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Definition
| Supply of monomers (or precursors of) required by cells for growth |
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Definition
| Nutrients required in large amounts |
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Definition
| Nutrients required in trace amounts |
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Definition
Required by ALL cells
Typical bacterial cell is ~50% carbon (by dry weight)
Major element in ALL classes of macromolecules
Heterotrophs use organic carbon
Autotrophs use carbon dioxide (CO2) |
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Term
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Definition
Typical bacterial cell is ~13% nitrogen
(by dry weight)
Key element in proteins, nucleic acids, and many more cell constituents |
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Term
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Definition
| Synthesis of nucleic acids and phospholipids |
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Term
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Definition
Sulfur-containing amino acids (cysteine and methionine)
Vitamins (e.g., thiamine, biotin, lipoic acid) and coenzyme A |
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Term
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Definition
| Required by enzymes for activity |
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Term
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Definition
Stabilizes ribosomes, membranes, and nucleic acids
Also required for many enzymes |
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Definition
Helps stabilize cell walls in microbes
Plays key role in heat stability of endospores |
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Definition
| Required by some microbes (e.g., marine microbes) |
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Definition
| Key component of cytochromes and FeS proteins involved in electron transport |
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Definition
Organic compounds required in small amounts by certain organisms
Examples: vitamins, amino acids, purines, pyrimidines |
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Definition
Most commonly required growth factors
Most function as coenyzmes |
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Term
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Definition
| Nutrient solutions used to grow microbes in the laboratory |
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Term
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Definition
Defined media: precise chemical composition is known
Complex media: composed of digests of chemically undefined substances (e.g., yeast and meat extracts) |
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Term
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Definition
| Contain complex media plus additional nutrients |
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Term
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Definition
| Contain compounds that selectively inhibit growth of some microbes but not others |
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Term
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Definition
| Contain an indicator, usually a dye, that detects particular chemical reactions occurring during growth |
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Term
| For successful cultivation of a microbe, |
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Definition
| it is important to know the nutritional requirements and supply them in proper form and proportions in a culture medium |
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Term
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Definition
| culture containing only a single kind of microbe |
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Term
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Definition
| unwanted organisms in a culture |
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Term
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Definition
liquid or solid culture media
Solid media are prepared by addition of a gelling agent (agar or gelatin)
When grown on solid media, cells form isolated masses (colonies) |
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Term
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Definition
Everywhere
Sterilization of media is critical
Aseptic technique should be followed |
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Term
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Definition
Streak plate
Pour plate
Spread plate |
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Term
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Definition
| each daughter cell receives a chromosome and sufficient copies of all other cell constituents to exist as an independent cell |
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Term
| Production of new cell wall material is a major feature of |
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Definition
cell division
In cocci, cell walls grow in opposite directions outward from the FtsZ ring
In rod-shaped cells, growth occurs at several points along length of the cell |
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Term
| Preexisting peptidoglycan needs to be severed to |
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Definition
allow newly synthesized peptidoglycan to form
Beginning at the FtsZ ring, small openings in the wall are created by autolysins
New cell wall material is added across the openings |
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Term
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Definition
| junction between new and old peptidoglycan |
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Term
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Definition
final step in cell wall synthesis
Forms the peptide cross-links between muramic acid residues in adjacent glycan chains
Inhibited by the antibiotic penicillin |
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Term
| Generation time is dependent on |
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Definition
| growth medium and incubation conditions |
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Term
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Definition
growth of a microbial population in which cell numbers double within a specific time interval
During exponential growth, the increase in cell number is initially slow but increases at a faster rate |
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Term
| A relationship exists between the initial number of cells present in a culture and the number present after a period of exponential growth: |
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Definition
N = N02n
N is the final cell number
N0 is the initial cell number
n is the number of generations during
the period of exponential growth |
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Term
| Generation time (g) of the exponentially growing population is |
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Definition
g = t/n
t is the duration of exponential growth
n is the number of generations during
the period of exponential growth |
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Term
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Definition
| a closed-system microbial culture of fixed volume |
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Term
| Typical growth curve for population of cells grown in a closed system is characterized by four phases |
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Definition
Lag phase
Interval between inoculation of a culture and beginning of growth
Exponential (Log)phase
Cells in this phase are typically in the healthiest state
Stationary phase
Growth rate of population is zero
Either an essential nutrient is used up, or waste product of the organism accumulates in the medium
Death phase
If incubation continues after cells reach stationary phase, the cells will eventually die |
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Term
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Definition
| an open-system microbial culture of fixed volume |
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Term
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Definition
most common type of continuous culture device
Both growth rate and population density of culture can be controlled independently and simultaneously
Dilution rate: rate at which fresh medium is pumped in and spent medium is pumped out
Concentration of a limiting nutrient |
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Term
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Definition
The growth rate is controlled by dilution rate
The growth yield (cell number/ml) is controlled by the concentration of the limiting nutrient |
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Term
| Chemostat cultures are sensitive to |
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Definition
the dilution rate and limiting nutrient concentration
At too high a dilution rate, the organism is washed out
At too low a dilution rate, the cells may die from starvation
Increasing concentration of a limiting nutrient results in greater biomass but same growth rate |
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Term
| Microbial cells are enumerated by |
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Definition
microscopic observations
Results can be unreliable |
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Term
| Limitations of microscopic counts |
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Definition
Cannot distinguish between live and dead cells without special stains
Small cells can be overlooked
Precision is difficult to achieve
Phase-contrast microscope required if a stain is not used
Cell suspensions of low density (<106 cells/ml) hard to count
Motile cells need to immobilized
Debris in sample can be mistaken for cells |
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Term
| A second method for enumerating cells in liquid samples |
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Definition
is use of a flow cytometer
Uses laser beams, fluorescent dyes, and electronics |
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Term
| Viable cell counts (plate counts): |
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Definition
measurement of living, reproducing population
Two main ways to perform plate counts:
Spread-plate method
Pour-plate method |
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Term
| To obtain the appropriate colony number, the sample to be counted should always be |
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Definition
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Term
| Plate counts can be highly unreliable when used to assess total cell numbers of natural samples (e.g., soil and water) |
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Definition
| Selective culture media and growth conditions target only particular species |
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Term
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Definition
direct microscopic counts of natural samples reveal far more organisms than those recoverable on plates
Microscopic methods count dead cells, whereas viable methods do not
Different organisms may have vastly different requirements for growth |
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