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Microbiology Exam I

Microbiology @ UML 2012
STUDY
PLAY
Organisms that can grow in habitats with low water activity by maintaining a high internal salt concentration are called __________ organisms.
osmotolerant
Organisms that require high levels of sodium chloride in order to grow are called __________ organisms.
halophilic
Organisms that have their optimum growth pH between 0.0 and 5.5 are called __________.
acidophiles
Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.
neutrophiles
Organisms that have their optimum growth pH between 8.5 and 11.5 are called __________.
alkaliphiles
Organisms that grow best at pH levels above 10 are called __________ __________.
extreme alkaliphiles
Organisms with growth temperature maxima between 85 and 113°C are referred to as __________.
hyperthermophiles
Complex microbial communities that grow tightly adhered to surfaces are called __________.
biofilms
Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.
growth
An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a
Culturostat
In a continuous culture system, the rate at which media is added and removed is called the __________ rate.
Flow-through
Organisms that grow well at 0°C and have optimum growth temperatures of 15°C or lower are called
Psychrophiles
Organisms that grow at 0°C and have a maximum growth temperature of 35°C are called
mesophiles
Organisms that do not require oxygen for growth but grow better in its presence are called
facultative anaerobes
Organisms that ignore oxygen and grow equally well in its presence or absence are called
aerotolerant
Organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2-10% for growth are called
microaerophiles
The membranes of psychrophilic bacteria have relatively high levels of __________ fatty acids, which allow them to remain semi-fluid at cold temperatures.
sterol
Organisms that are not drastically affected by increased pressure are called
barotolerant
Most microorganisms maintain their internal pH
near their optimal growth pH
The cell wall of bacteria constrains the ___________ _________ that results from the osmolarity of the cytoplasmic contents.
Turgor pressure
The site at which replication of DNA starts in bacterial cells is known as the __________ of ___________.
origin; replication
The __________ __________ is the length of time it takes for a population of microorganisms to double in number.
generation time
Growth is said to be __________ when all cellular components are synthesized at constant rates relative to one another.
balanced
Organisms that can grow in habitats with low water activity by maintaining a high internal salt concentration are called __________ organisms.
osmotolerant
Organisms that have their optimum growth pH between 0.0 and 5.5 are called __________.
acidophiles
Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.
neutrophiles
Organisms that have their optimum growth pH between 8.5 and 11.5 are called __________.
alkaliphiles
Organisms that grow best at pH levels above 10 are called __________ __________.
extreme alkaliphiles
Organisms with growth temperature maxima between 85 and 113°C are referred to as __________.
hyperthermophile
Complex microbial communities that grow tightly adhered to surfaces are called __________.
biofilms
Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.
growth
If all cell components are synthesized at constant rates relative to one another, the culture is said to be in __________ growth; however, if the rates of synthesis of some components change relative to the rates of synthesis of other components, the culture is said to be in __________ growth.
balanced;unbalanced
The purpose of the penicillin binding proteins is to link phospholipids together in the cellular membrane.
False
When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short or absent.
False
The growth rate of a given species of microorganism is dependent on the composition of the medium in which it is grown.
True
The primary mechanism by which DNA is damaged by ultraviolet radiation involves the formation of thymine dimers.
Trie
A microbial environment containing high nutrient concentrations is called an oligotrophic environment.
False
When the cell elongates, replicates its chromosome, and separates the chromosome into the two parts of the cell, and a septum forms at midcell, this process is called _______________.
Binary Fission
The limitation on microbial growth rate at high nutrient levels is
the saturation of transport proteins for nutrient uptake
The total number of viable microorganisms remains constant in stationary phase because
either there is a balance between cell division and death or there is a cessation of cell division even though the cells may remain metabolically active
A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.
batch
Which of these methods can be used to determine the number of viable microorganisms in a sample?
Measuring colony forming units per ml
When a microorganism is placed in a(n) __________ solution, water will enter into the cell and cause it to burst unless something is done to prevent this.
hypotonic
Organisms that grow near deep-sea volcanic vents are likely to be
thermophilic
Organisms that grow near deep-sea volcanic vents are likely to be
barophilic or barotolerant
Organisms that grow in the mud under relatively nonturbulent bodies of water are likely to be
anaerobes
Membranes of thermophilic bacteria are stabilized by phospholipids with
fatty acids that tend to be more saturated
The length of the lag phase of growth can vary depending on
all of the choices
At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the culture enters stationary phase with a population of 65 million cells. At what time is the population half maximal?
8:40PM
At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has a population of 65 million cells. The mean generation time is approximately
20 minutes
The trace amounts of micronutrients needed by microorganisms are usually supplied as inadvertent contaminants in water and regular media components.
True
Zinc (Zn) is considered a macronutrient.
False
Copper (Cu) is considered a micronutrient.
True
Which of the following is not a major class of growth factors?
nucleic acids
__________ membranes allow some molecules to pass but not others.
Selectively permeable
Bacteria that can utilize methane, methanol, carbon monoxide, formic acid, and a few related one-carbon molecules as their principal source of carbon are called ____________.
methylotrophic
__________ membranes allow some molecules to pass but not others.
Selectively permeable
Which of the following is not considered a macronutrient?
cobalt (Co)
Which of the following is not considered a micronutrient?
magnesium (Mg)
Which of the following features is most likely to be associated with a lithotroph?
oxidization of an inorganic substrate
Which of the following processes can be used to bring nutrients into a cell against a concentration gradient?
active transport
Agar is an excellent solidifying agent for microbiological media because
it is not degraded by most microorganisms and solid agar remains solid until the temperature is raised to 90°C, and liquid agar remains liquid if the temperature is lowered to 45°C are correct.
A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a __________ medium.
selective
A growth medium that distinguishes among different groups of bacteria on the basis of their biological characteristics is called a __________ medium.
differential
Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes); nonhalophiles will not grow. Among the halophiles, mannitol fermenters will produce acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter and a halophilic mannitol nonfermenter. In this case, the medium is acting as (a) __________ medium(s).
differential
Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol nonfermenter and a nonhalophilic mannitol nonfermenter. Here the medium acts as a __________ medium.
selective
Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter, a nonhalophilic mannitol fermenter, and a halophilic mannitol nonfermenter. Thus, the medium is acting as a __________ medium.
selective and differential
You would like to culture a bacterium that is growing in the lung of a human patient with pneumonia. Which media would be of most use in culturing this organism?
complex medium supplemented with whole blood
All fastidious microorganisms require which of the following for growth?
extra nutrients (such as whole blood)
Which of the following can be used to isolate pure cultures of bacteria from mixtures?
all of the choices
Sulfur can be obtained from inorganic sources only.
False
Nitrogen can be obtained from either organic or inorganic sources.
True
Permease proteins that aid in the transport of nutrients resemble enzymes in their specificity for the substance to be transported. Each carrier is selective and will transport only a closely related set of substances.
True
The size and shape of a colony is not useful for identification of a microorganism because most microorganisms produce colonies that are indistinguishable from one another.
False
Serial dilutions can be used to estimate the total number of bacterial cells in a solution, including living and dead cells.
False
A branched network of hyphae formed by the Actinomycetes is called a __________.
mycelium
Actinomycetes form long filaments called ___________.
hyphae
Molecules or regions of molecules that readily interact with water are said to be __________, whereas molecules or regions of molecules that are insoluble in water or do not readily interact with water are said to be hydrophobic.
hydrophilic
A(n) __________ layer is a layer of protein or glycoprotein that exhibits a pattern resembling floor tiles.
S
The most widely accepted current model for membrane structures is called the __________ model.
fluid mosaic
_______ is a peptidoglycan-like molecule found in the cell walls of some archaea.
Pseudomurein
Intracellular granules of organic or inorganic material that are stockpiled by bacteria for future use are called __________.
inclusions
Bacteria have a region of the cytoplasm known as the __________, which is not bounded by a membrane but contains the chromosome.
nucleoid
Small circular DNA molecules capable of replicating and containing genes that are useful but not necessary to the bacterium are called __________.
plasmids
Some species of aquatic bacteria use inclusion bodies known as ________ to orient themselves in Earth's magnetic field.
magnetosomes
_______ are the site of protein synthesis in the cell.
Ribosomes
Bacterial flagella are composed of three parts: the ______ body, which is embedded in the cell, the hook, and the _______, which is the longest part of the flagellum.
basal, filament
The term used to describe bacteria that are intermediate in shape between spherical and rod-shaped is
coccobacilli
Bacterial cells that are variable in shape are called
pleomorphic
Square planar arrangement of cells that forms when round bacteria remain attached to each other during reproduction are called
tetrads
Flexible bacteria with a helical shape are called
spirochetes
Rigid bacteria with a helical cell shape are called
spirilla
The term used to describe bacteria that are shaped like curved rods is
vibrio
The term used to describe bacteria that are rod shaped is
bacillus
The term used to describe bacteria that have a spherical shape is
coccus
The lipopolysaccharide (LPS) that is found in the outer membrane of gram-negative bacteria is also known as
endotoxin
Proteins that are loosely associated with the cytoplasmic membrane are called __________ proteins.
peripheral
Proteins that are embedded within the cytoplasmic membrane and not easily extracted are called __________ proteins.
integral
Lipids with polar and nonpolar ends are said to be
amphipathic
Bacterial and archaeal ribosomes are known as _____ ribosomes, based on their sedimentation coefficient.
70S
Twitching or gliding motility involves
both type IV pili and movement of slime can be involved in twitching or gliding motility.
Sortase is a protein enzyme of bacteria that
catalyzes covalent attachment of some surface proteins to peptidoglycan.
Invisible living creatures were thought to exist and cause disease long before they were ever observed.
True
Agar is used as a solidifying agent for microbiological media because it is not readily digested by most microorganisms.
True
The usefulness of agar in solidifying microbiological growth media is limited because it does not remain solid at temperatures about 28oC.
False
Some microorganisms are useful in bioremediation processes that reduce the effects of pollution.
True
Light rays are refracted (bent) when they cross the interface between materials with different refractive indices.
True
A substage condenser is used to focus light onto the specimen, which increases the resolution of a light microscope.
True
Confocal microscopes, in combination with specialized computer software, can be used to create three-dimensional images of cell structures.
True
Resolution decreases when the wavelength of the illuminating light decreases.
False
Immersion oil is used to prevent a specimen from drying out.
False
Immersion oil increases the amount of light passing through a specimen and entering the objective lens.
True
Gram staining divides bacterial species into roughly two equal groups.
True
Negative staining facilitates the visualization of bacterial capsules which are intensely stained by the procedure.
False
Negative staining with India ink can be used to reveal the presence of capsules that surround bacterial cells.
True
Mordants increase the binding between a stain and specimen.
True
In order to stain flagella so that they may be readily observed by light microscopy, it is usually necessary to increase their thickness.
True
It was possible to view viruses only after the invention of the electron microscope because they are too small to be seen with a light microscope.
True
During the assembly of the flagellar filament, the flagellin protein monomers assemble at the cell proximal base of the flagellum.
False
Although a particular microbial species usually can be defined as a particular nutritional type, some show great metabolic flexibility and alter their metabolic patterns in response to environmental changes.
True
Phosphorus can be obtained from organic sources only.
False
Organisms usually have only a single transport system for any nutrient.
False
Different transport systems for the same nutrient that are part of the same organism are usually regulated in different ways.
True
The extreme insolubility of ferric iron leaves little free iron available for transport into bacterial cells.
True
Blood agar is both a differential and enriched medium.
True
All bacterial and archaeal cells are diploid.
False
During the lag phase of microbial growth, the cells are metabolically inactive.
False
One of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time.
True
Obligate anaerobes are usually poisoned by molecular oxygen but may grow in aerobic habitats if associated with facultative anaerobes that use up all available oxygen.
True
DNA of thermophiles is stabilized by binding of special nucleoid-associated proteins.
True
Membranes of some thermophilic Archaea are stabilized by ether linked phospholipids.
True
Cells with a relatively complex morphology that have a true membrane-delimited nucleus are called
Eukaryotes
Cells with a relatively simple cell morphology that do not have a true membrane-delimited nucleus are called
Prokaryotes
Definition of life includes all of the following except
cells lack response to external environment
Proteins function in modern cells as
catalysts;structural elements
RNA serves to convert the information stored in DNA to ________.
protein
Who of the following provided the evidence needed to discredit the concept of spontaneous generation?
Pasteur
The concept that living organisms arise from nonliving material is called
Spontaneous generation
Studies by Emil von Behring and Shibasaburo Kitasato demonstrated that inactivated toxins can induce the synthesis of antitoxins in the blood of rabbits. These antitoxins (antibodies) are the basis of
Humoral immunity
Old cultures of bacteria that have lost their ability to cause disease are said to be
Attenuated
Which of these microscopes can be used to create high-resolution three-dimensional images of cells?
Confocal
A 30× objective and a 20× ocular produce a total magnification of
600x
A 45× objective and a 10× ocular produce a total magnification of
450x
A microscope that exposes specimens to ultraviolet, violet, or blue light and forms an image with the light emitted at a different wavelength is called a __________ microscope.
Fluorescence
Immersion oil can be used to increase the resolution achieved with some microscope lenses because it increases the __________ between the specimen and the objective lens.
Neither optical density nor refractive index
If the objective lenses of a microscope can be changed without losing focus on the specimen, they are said to be
Parfocal
An instrument that magnifies slight differences in the refractive index of cell structures is called a (n) __________ microscope.
Phase-contrast
The instrument that produces a bright image of the specimen against a dark background is called a (n) __________ microscope.
Dark-field
Acid-fast organisms such as Mycobacterium tuberculosis contain __________ constructed from mycolic acids in their cell walls.
lipids
In the Gram-staining procedure, the decolorizer is
ethanol or acetone.
Which of the following is considered to be a differential staining procedure?
Acid-fast stain
Basic dyes such as methylene blue bind to cellular molecules that are
Anionic
The Gram-staining procedure is an example of:
Differential staining
Shrinkage of the plasma membrane away from the cell wall when the bacterium is placed in a hypertonic environment is called
Plasmolysis
A feature unique to some archaeal plasma membranes is that they may
contain sterols such as cholesterol.
The power used by most bacterial flagellar motors is produced by
proton motive force (PMF)
A feature unique to some archaeal plasma membranes is that they may
consist of a lipid monolayer.
The power used by most bacterial flagellar motors is produced by
proton motive force (PMF)
Elements that are required in relatively large amounts by microorganisms are called
macronutrients.
Organisms that use reduced, preformed organic molecules as carbon sources are
heterotrophs
Organisms that can use carbon dioxide as their sole or principal source of carbon are
autotrophs
Organisms that obtain electrons from the oxidation of inorganic compounds are called
lithotrophs
Organisms that obtain electrons from the oxidation of organic compounds are called
organotrophs
Organisms that obtain energy from the oxidation of either organic or inorganic compounds are called
chemotrophs
Media containing some ingredients of unknown chemical composition are called __________ media.
Complex
For surface cultivation of microorganisms, a sulfated polymer called agar can be extracted from __________ and added to liquid media in order to cause it to solidify.
algae
Media in which all components and their concentration are known are called __________ media.
defined
Most bacterial and archaeal cells divide by
binary fission
The __________ is a group of proteins needed for DNA synthesis that assembles at the origin of replication.
Replisome
The process of forming a cross wall between two daughter cells is known as
Septation
The actin-like protein that seems to be involved in determining cell shape is
FtsZ
During cytokinesis, a critical step in septation is the assembly of the
Z-Ring
Microorganisms are most nearly uniform in terms of chemical and physiological properties during __________ phase.
Exponential
A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.
continuous
An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate that medium containing microorganisms is removed is called
chemostat
An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a
turbidostat
A microscope that illuminates the specimen directly with bright light and forms a dark image on a brighter background
bright-field microscope
Staining procedures that divide bacteria into separate groups based on staining properties.
differential staining
Simple staining
Staining a specimen with a single dye
A light microscope in which monochromatic laser derived light scans across the specimen at a specific level. Stray light from above and below the plane of focus is blocked out to give an image with excellent contrast and resolution.
Confocal Microscope
A rod shaped bacterial archaeal cell
Bacillus
A layer of well organized material, not easily washed off, lying outside the cell wall of various microbes
Capsule
A component of bacterial cell walls. It is composed of long chains of alternating N-acetylglucosamine and N-acetylmuramic acid residues, with the chains linked to each other by short chains of amino acids
Peptidoglycan
The space between the plasma membrane and outermost layers of the bacterial cell wall; larger in gram- bacteria; gram+ bacteria secrete exozymes to degrade polymeric nutrients
periplasmic space
Proteins that form channels for the transport of small molecules across the outer membrane of gram-negative bacterial cell walls.
Porin proteins
Thin protein appendages required for bacterial conjugation; cells with sex pili donate DNA to recipient cells.
sex pili
A regularly structured layer composed of protein or glycoprotein that lies on the surface of many bacteria and archaea; helps resist antibiotics and increase virulence
S-layer
A rigid, spiral-shaped bacterial or archaeal cell.
spirillum
A flexible, spiral-shaped bacterium with periplasmic flagella.
spirochete
Roughly spherical shaped cells that can be paired(diplo-) or alone
Cocci
Comma shaped bacterium that are similar to rods
Vibrios
a branched network of hyphae
Mycelium
having variable shapes/lacking a characteristic shape
Pleomorphic
The plasma membrane and all the surrounding layers external to it
Cell Envelope
Loosely connected to the plasma membrane and is easily removed due to its aqueous solubility
Peripheral
Proteins that are hydrophobic and are difficult to remove from the plasma membrane
Integral
Lipid component of the plasma membrane of bacteria that is similar in structure to steroids; is thought to stabilize the plasma membrane
Hopanoids
A large polymer composed of long chains of alternating N-acetylglucosamine and N-acetylmuramic acid residues that are connected by tetrapeptide bonds; helical structure allows it to connect to structures above, below, and to each side
Murein
Secondary wall polymers of glycerol and ribitol joined by phosphate groups; covalent linkage to the peptidoglycan/plasma membrane lipids(lipoteichoic acids) maintain stability; teichoic acids are responsible for the anionic charge on the surface of gram+ bacteria; absent in gram- bacteria
Teichoic Acids
Present in the G+ acid fast bacteria, it is thought that they form a lipid bilayer on the peptidoglycan layer which is analogous to the G- outer membrane
Mycolic acid
A small lipoprotein in G- bacteria that is thought to link the outer membrane to via a hydrophobic end and a covalent link to the peptidoglycan.
Brauns Lipoprotein
Lipopolysaccharides are present in the outer membrane and consist of Lipid A(an endotoxin), a polysaccharide core and an O antigen.

Important functions include: Anionic charge from the sugars phosphate groups, stabilization of outer membrane and in surface adhesion, and the formation of a permeability layer that restricts the entry of bile, antibiotics, etc....

Porin proteins permit the passage of monosaccharides
LPS
How do archaeal plasma membranes differ from bacteria or eukaryotes?
Their hydrocarbons are derived from isoprene units; hydrocarbons are bonded by ether links, as opposed to the usual ester
What is pseudomurein?
Pseudomurein is a peptidoglycan like molecule that differs in that it has L-amino acids instead of D-amino acids in its cross links, and utilizes N-acetyltalosaminuronic acid instead of N-acetylmuramic acid; as well as β(1→3) glycosidic bonds instead of β(1→4) glycosidic bonds
FtsZ
Widely observed in Bacteria and Archaea, it functions in cell division
FtsA
Functions in cell division, observed in many bacterial species
MreB/Mbi
Maintains cell shape, segregates chromosomes and localizes proteins; present in most rod shaped bacteria
CreS
Crescentin, or CreS, induces a curvature in the curved rod bacteria
MinD
Prevents the polymerization of FtsZ at the cell poles in many rod shaped bacteria