Microbiology Connect HW Exam 3
_______ are viruses that are capable of infecting and selectively killing cancer cells.
Oncolytic viruses
In which type of infection does the virus remain in the host for years, sometimes without symptoms?
Persistent
Which are the two major categories of viral infections?
Persistent Acute
Place the following taxonomic categories in the correct order from the largest (most inclusive) to the smallest, starting at the top.
Phylum. Class, Order, Family, Specie, Genus
______ assays are routinely used to quantify phage particles in environmental samples such as sewage.
Plaque
The causative agent of malaria is the genus ______, which is a member of the group of protozoa called _______.
Plasmodium; apicomplexans
Match each possible outcome of phage replication with the correct definition.
Productive infection: New viral particles are produced Latent state: Viral genome remains silent within the cell
Which of the following are diseases caused by member of the Chlamydia and Chlamydophila species?
Psittacosis, a form of pneumonia A sexually transmitted infection that mimics gonorrhea Atypical pneumonia Eye infections
The replication strategy of viruses can be divided into three general categories: those used by ______.
RNA viruses DNA viruses reverse transcribing viruses
Reverse transcriptase is a(n) ______ polymerase.
RNA-dependent DNA
Replicases are ______ polymerases.
RNA-dependent RNA
Which of the following proteins is essential for maintenance of the lysogenic state?
Repressor
Which of the following processes are required for production of virus particles in a host cell?
Transcription of viral genes Translation of viral genes Replication of viral genome
What mechanisms do newly assembled viruses use to leave their host cell?
Triggering apoptosis Budding
Cyanobacteria are morphologically diverse, ranging in shape from unicellular organisms to filamentous multicellular associations.
True
In species with septate hyphae, the cytoplasm is interconnected because of pores in the cross walls.
True
Normal prion proteins can have the same amino acid sequence as the abnormal form of the protein.
True
Some lysogenic phages can increase the pathogenicity of their bacterial host.
True
The asexual reproductive forms of fungi are the most relevant cells for identification in medical microbiology.
True
Which of the following are non-cellular infectious agents composed of only a single-stranded RNA molecule?
Viroids
Which of the following are non-cellular infectious agents?
Viroids Prions Viruses
Which facts best support the position that viruses are not living organisms?
Viruses are inert outside of a host. Viruses cannot reproduce on their own.
Which of the following statements about virus nucleic acid is true?
Viruses contain either DNA or RNA.
Which of the following statements about virus nucleic acid is true? All viruses contain protein and RNA. Viruses contain either DNA or RNA. Viruses contain both DNA and RNA. All viruses contain protein and DNA.
Viruses contain either DNA or RNA.
Which statements regarding viruses are true? The terms virus and phage are interchangeable. Some viruses can infect both prokaryotic cells and eukaryotic cells. Viruses that infect bacteria are called bacteriophages.
Viruses that infect bacteria are called bacteriophages.
Match each type of fungus with its description.
Yeasts- Single-celled fungi Molds- Filamentous fungi Mushrooms- Reproductive structures of certain fungi
Which of the following statements best describes protozoa?
animal-like unicellular organisms
The accumulation of mutations in genes that encode viral surface proteins recognized by the immune system results in a type of antigenic variation called ______.
antigenic drift
When two different strains of a segmented virus enter the same cell, reassortment of the gene segments can occur, resulting in ______.
antigenic shift
The terms definitive host and intermediate host are associated with what protozoan group?
apicomplexans
How do aerobic chemoorganotrophs obtain their energy?
by using O2 as a terminal electron acceptor by oxidizing organic compounds
Azotobacter species produce a resting cell called a(n)__________ , that allows the organism to withstand drying and ultraviolet radiation.
cyst
The resting cell produced by Azotobacter species that allows the organism to survive drying and ultraviolet radiation is called a(n) ______.
cyst
Morphological changes in host cells that are caused by viral infection are referred to as
cytopathic
Multinucleated cells and inclusion bodies are examples of
cytopathic effects
When an enveloped virus gains entry to an animal cell by fusion, the virus envelope fuses with the ______.
cytoplasmic membrane
The following steps occur during sexual reproduction in fungi. Place them in order starting with the earliest at the top.
fusion of hyphae fusion of nuclei meiosis
____transduction is the result of packaging errors during the assembly stage of phage replication.
generalized
Commercially important contributions attributed to fungi include ______.
genetically engineered production of insulin and vaccines the synthesis of antibiotics uses in the wine and cheese industries
The normal habitat of Bacteroides species in humans includes the ______.
genital tract intestines mouth
Key characteristics used in the classification of viruses are ______.
genomic structure and host range
Which of the following are found in the cell walls of fungi?
glucan chitin
In the case of animal viruses, the molecules that viral spikes attach to on the host cell in order to gain entry are typically ______.
glycoproteins
Temperate phages are more likely to enter the lysogenic cycle when bacterial cells are ______.
growing slowly
A mycosis is caused when a fungus ______.
grows on or in the human body and causes disease
Superficial fungi affect the ______.
hair skin nails
Prokaryotes that grow well in an environment that contains 32% NaCl would be called extreme
halophiles
All of the following are required for synthesis of new virus particles in a host cell EXCEPT ______. protein synthesis genome replication homologous recombination RNA synthesis
homologous recombination
Symptoms of acute viral diseases result from ______.
host immune response host tissue damage
Molds produce intertwined thread-like multicellular filaments called
hyphae
Most viruses have one of three different shapes:
icosahedral, helical, complex
Fungi are more likely to cause severe disease in ______ than in any other group.
immunocompromised patients
Deposits of diatoms are used ______.
in filtering systemsas an abrasive in polishes
Fungi can be found ______.
in many different types of habitat on Earth
Typically, most fungi grow ______.
in the presence of O2 in terrestrial environments between 20oC to 35oC
The process of a prophage being excised and entering the lytic cycle is ______.
induction
Through the process of phage ________ , a prophage is excised and enters the lytic cycle.
induction
Viruses are best described as
infectious agents
Slime molds ______
ingest organic matter are important in the food chain are terrestrial organisms are composed of ameboid cells
The most important transmitters of plant viruses are probably ______.
insects
During the process that leads to a lysogenic infection, which of the following inserts the phage DNA into a bacterial chromosome?
integrase
Lysogeny is best described as
integration of the viral genome into the host chromosome
Enterobacteriaceae get their name because they reside in the ______ tract of humans and animals.
intestinal
In the case of RNA viruses that have a single strand (+) RNA genome, the viral genome ______.
is used as a template to make complementary (-) RNA strands that act as templates to produce more (+) RNA strands can be translated to make proteins
The study of bacteriophages has advanced much faster than investigations on animal viruses in part because ______.
it is easier to grow bacterial cells than animal cells
A group of Gram-negative bacteria that serve as an important model in the study of developmental biology because of their unique developmental cycle that includes the production of a fruiting body are the
myxobacteria
The smallest virus is approximately 10 ______ in diameter.
nanometers
Naked viruses do not have an outer lipid bilayer. These viruses are called
non-enveloped viruses
At minimum, all viruses are composed of
nucleic acids and proteins
In animals, replication of most DNA viruses occurs within the host cell's
nucleus
Unlike animal viruses that attach to specific receptors in order to gain entry into the cell, _________ viruses can gain entry into a cell through damage in the cell wall.
plant
In a(n) ______, viral titer can be determined by counting clear zones in a monolayer of cells.
plaque assay
DNA viruses often encode their own DNA __________ for DNA synthesis, which allows them to replicate even if the host cell is not actively duplicating its own chromosome.
polymerase
An infectious agent that consists of protein and no nucleic acid is called a(n)
prion
Mad cow disease and chronic wasting disease are caused by infectious agents called
prions
Transmissible spongiform encephalopathies are caused by ______.
prions
______ are the causative agents of transmissible spongiform encephalopathies.
prions
As a group, anaerobic chemoorganotrophs ______.
produce ATP via substrate level phosphorylation can obtain energy via fermentation
Specialized transduction ______.
produces defective phage particles results from errors in excision of the prophage transfers phage DNA and adjacent host genes
is the science that studies organisms in order to arrange them into groups; it can be viewed as three separate interrelated areas: identification, classification, and nomenclature.
taxonomy
A ______ phage can either cause a lytic infection or can incorporate its DNA into the host genome as a prophage.
temperate
Bacteriophages that can enter into a lytic cycle or a lysogenic cycle are called ______- phages.
temperate
Slime molds are ______.
terrestrial organisms
In general, fungi are _______ organisms that grow better than bacteria on ______ fruits and vegetables and on bread.
terrestrial; acidic
Viral infections in plants can cause diseases ______.
that are economically devastating
Bacteria are given names according to internationally recognized rules based on which of the following?
the International Code of Nomenclature of Prokaryotes
In a lysogenic infection, ______.
the bacteriophage DNA integrates into the host chromosome
All of the following are reasons why sequencing the genes of small subunit (SSU) rRNA is extremely useful in classifying organisms EXCEPT ______.
the genes are often horizontally transferred
Enveloped viruses can derive their envelopes from ______.
the host cytoplasmic membrane certain host organelles
In acute viral infections, although the infected host cells may die, the host may survive because ______.
the host's immune system may gradually eliminate the virus
To determine whether a chloroplasts originated from primary, secondary, or even tertiary endosymbiosis, you can examine ______.
the number of membranes surrounding the chloroplasts
Hemoflagellates are characterized by ______.
the presence of a single large mitochondrion with thousands of interlocking molecules of circular DNA
single strand + RNA viruses
the viral genome functions as mRNA and is translated
Which of the following can be used to distinguish between members of the genus Bacillus and Clostridium?
their oxygen requirements
Scientists are interested in studying the growth of extreme ____________, archaea that grow near volcanic vents and fissures because these conditions are thought to mimic early earth's environment.
thermophiles
All of the following are characteristics shared by both Helicobacter and Campylobacter EXCEPT ______.
they cause diarrheal disease in humans
Some arthropods and worms are included in the study of microscopic Eukarya because _____.
they play important roles in human disease they are often carried or transmitted in forms that are microscopic
The most common method used today in the cultivation of animal viruses is ______.
tissue culture
Bacteriophages play a fundamental role in a type of horizontal gene transfer called
transduction
What term is used to describe the transfer of genetic information from one bacterium to another bacterium by a bacteriophage?
transduction
Which type of infection can be characterized by the sudden onset of symptoms of a relatively short duration?
Acute
About 75% of all known fungi are members of the phylum __________ . These include Penicillium species, morels, and truffles.
Blank 1: Ascomycota or Ascomycetes
The major categories of animal viral infections are _________ infections, characterized by the sudden onset of symptoms of a relatively short duration, and _________ infections that can continue with or without symptoms for years.
Blank 1: acute Blank 2: persistent
A generalized infection cycle of an animal viruses can be divided into five steps: 1. _________; 2. ________ entry; 3. ____________; 4. __________assembly; and 5. ____________ .
Blank 1: attachment, attach, or adsorption Blank 2: genome Blank 3: synthesis or biosynthesis Blank 4: release or lysis
Enveloped viruses exit host cells by __________; non-enveloped viruses are released upon ___________ of the host cell.
Blank 1: budding Blank 2: apoptosis or death
Fungi differ from most other eukaryotic organisms in that their cell walls contain __________, and their cell membranes contain ____________
Blank 1: chitin Blank 2: ergosterol
The taxonomic category called ________ is a collection of similar phyla or divisions.
Blank 1: kingdom or kingdoms
An organism that cannot reproduce outside of a host cell is termed an ___________ parasite.
Blank 1: obligate Blank 2: intracellular
This figure depicts how chloroplasts originated via a mechanism called
Blank 1: primary Blank 2: endosymbiosis
Blooms of toxin-producing photosynthetic dinoflagellates are commonly known as
Blank 1: red Blank 2: tides
Algae can grow in which of the following environments?
Both fresh water and salt water
The cells of species in the genus Neisseria are ______.
Gram-negative typically found in pairs cocci
Which of the following infections are analogous to lysogenic infections by bacteriophages in that they involve a viral genome that is silent in the host cell?
Latent
Which of the following describe a type of relationship that bacteriophages can have with their host? Latent infection where host cell genotype is changed Latent infection where the host cell lyses Productive lytic infection
Latent infection where host cell genotype is changed Productive lytic infection
A life form commonly found on rocks that results from a symbiotic relationship between a fungus and a photosynthetic microorganism is called a(n) _______
Lichen
______ include the sexually transmitted pathogen Trichomonas vaginalis.
Lumen-dwelling flagellates
Which of the following describes a consequence of lysogeny that could result in human disease?
Lysogenic conversion
______ is a change in the phenotype of a lysogen as a consequence of the specific prophage it carries.
Lysogenic conversion
______ is a revolutionary new technology being used in clinical labs that can rapidly identify an organism based on its protein profile.
MALDI-TOF mass spectrometry
Members of the genus ___________ are causative agents of gonorrhea and meningitis.
Neisseria
Methods used to increase the number of copies of specific DNA sequences can collectively be referred to as which of the following?
Nucleic acid amplification tests (NAATs)
Which is a nucleic acid amplification test (NAAT)?
PCR
A major advantage of commercial variations of traditional biochemical tests such as API strip tests is that they ______.
are less labor-intensive than traditional biochemical tests
A group of strains that have a characteristic biochemical pattern is called a _________, or biotype.
biovar
In a healthy individual, anaerobes can regularly be found on and in the ______.
intestinal tract oral cavity skin
Pulse Net, Genome Trakr, and Global Microbial Identifier are examples of surveillance networks and programs that use _________ _____________ sequence (WGS) data to help track infectious disease outbreaks both nationally and around the world.
Blank 1: whole Blank 2: genome
On what general principle do commercial variations of traditional biochemical tests operate?
A series of tiny wells containing different media are inoculated; metabolic activities yield a pattern of color changes used for identification.
Why can DNA sequences be viewed as evolutionary chronometers?
Accumulations of random mutations provide a relative measure of time elapsed since organisms diverged from a common ancestor.
_________ media are designed to reveal specific colony characteristics that can help in the initial identification of bacteria in clinical samples.
Differential
You work in a clinical lab. A sample you cultivated overnight on blood agar yielded β-hemolytic colonies, suggestive of Streptococcus pyogenes, a member of the lactic acid bacteria. Unlike most bacteria that grow in the presence of O2, lactic acid bacteria are catalase-negative. If a catalase test on a colony yielded a positive result, what would this tell you about the identity of your organism?
Your sample is not Streptococcus pyogenes.
The earliest oxygenic phototrophs probably belonged to a group of bacteria called the _______
cyanobacteria
Which of the following groups of bacteria is best described as a diverse group of photosynthetic Gram-negative bacteria that inhabit a wide range of environments?
cyanobacteria
All of the following information can generally be determined from microscopic examination of a microorganism EXCEPT ______.
definitively determining the genus and species of the microorganism
Match the taxonomic group to its appropriate definition.
family- a collection of similar genera order- a collection of similar families class- a collection of similar orders phylum- a collection of similar classes
An anaerobic chemoorganotroph that uses glucose for energy and pyruvate as its terminal electron acceptor is performing ______.
fermentation
Aerobic chemoorganotrophs gain energy via the _______, using O2 as a terminal electron acceptor.
oxidation of organic compounds
As a group, chemolithotrophs ______ to obtain energy.
oxidize reduced inorganic chemicals such as hydrogen gas
Which of the following are properties of Bacteria?
peptidoglycan cell wall 70S ribosomes
Microscopic morphology, culture characteristics, and fatty acid analysis are all examples of ______ characteristics used to identify prokaryotes.
phenotypic
Cyanobacteria are a group of _______ bacteria.
photosynthetic Gram-negative
The evolutionary relatedness of organisms is called
phylogeny
What term describes the evolutionary history of organisms?
phylogeny
Nitrogen fixation, or the process of converting nitrogen gas (N2) into ammonia, is an exclusive ability of ______.
prokaryotes
The basic taxonomic unit is the
species
The species designation gives a formal taxonomic status to a group of related isolates, or ______.
strains
Bacteria that oxidize sulfur are Gram-negative rods or spirals that ______.
use sulfur compounds as an energy source and oxygen as a terminal electron acceptor
How do obligate aerobes obtain energy?
using respiration only
Oxygenic phototrophs use ______ as a source of electrons for reducing power, generating O2.
water
Mycobacterium species stain poorly because their cell walls contain ______.
waxy lipids called mycolic acids
What is the definition of biovar or biotype?
A group of strains that have a characteristic biochemical pattern.
Dimorphic fungi are fungi that typically can ______.
exist as either a yeast or a mold
Prosthecate bacteria form projections called prosthecae, which are extensions of the cytoplasm and cell wall. These prosthecae ______.
facilitate absorption of nutrients
Facultative anaerobes can use aerobic respiration if O2 is present and _____________ if O2 is not available.
fermentation
Animal viruses can be studied by infecting ______.
fertilized chicken eggs live animals cell or tissue culture
______ phages cause productive infections that do not kill the host cell.
filamentous, M13, Temperate, or Lysogenic
The replication scheme of double-stranded DNA viruses ______.
follows the central dogma of molecular biology
The photosynthetic pigment responsible for the color of brown algae is ______.
fucoxanthin
In lichens, the _______ partner absorbs water and minerals for the symbiotic pair.
fungal
A number of antifungal medications target ergosterol because it can be found in ______.
fungal cell membranes but not in animal cell membranes
Water molds were once considered types of ______ because of their growth on decaying vegetation and their method of secreting enzymes to digest substrates.
fungi
Which of the following are eukaryotes? bacteria fungi algae multicellular worms arthropods
fungi algae multicellular worms arthropods
Microscopic eukaryotes include _________, which are heterotrophic organisms with chitin in their cell walls.
fungi, molds, or yeasts
The genus Streptomyces includes more than 500 species that resemble ______ in their growth but are ______.
fungi, prokaryotes
______ are the reproductive structures of certain fungi.
mushrooms
A tangle of fungal hyphae is generally known as a(n) ______.
mycelium
A visible mass of hyphae is called
mycelium
The branch of biology dealing with the study of fungi is called
mycology
Fungi growing in a mutually beneficial relationship with plant roots form associations called
mycorrhizas or mycorrhizae
The term ___________ is used to describe a disease caused by a fungus growing on or in the human body.
mycosis
____ is used to describe a disease caused by a fungus growing on or in the human body.
mycosis
____________ testing uses antibodies to detect characteristic proteins or polysaccharides that make up microorganisms.
serological
The fungal contribution to plants in an association called mycorrhizas includes ______.
supplying the plant with nitrogen and phosphorus increasing the ability of the plant to absorb water
The motile cells found in sheathed bacteria are called ______ cells, and these exit through the end of the sheath.
swarmer
I say: "Gram-negative bacteria, that are typically kidney-bean-shaped cocci in pairs. You say:
"Neisseria"
Of the single-stranded RNA viruses, some types have a ______ genome, which also serves as mRNA.
(+) strand
Match the genome of each type of RNA virus with its description of function.
(+) strand genome: Serves as mRNA (-) strand genome: Is the complement to mRNA Double-stranded genome: Consists of both a (+) and (-) strand
During viral replication, when the genome of a (+) single-stranded RNA virus is used as a template, which of the following is generated?
(-) single-stranded RNA molecules
A viral RNA genome that cannot be immediately translated into protein is a ______.
(-) strand
In ______-strand RNA viral genomes, the genome functions as an mRNA molecule.
+
Sexual reproduction in fungi occurs when hyphae of two different mating types grow towards one another and fuse. These two mating types are generally referred to as ______.
+ and -
You have a sample containing bacteria that cannot yet be grown in culture. You decide to use 16s rDNA sequences to identify the bacteria. What is the correct order of steps you should use? Start with the earliest at the top.
1. Extract DNA from the bacteria 2. Amplify the bacterial DNA 3. Clone the 16S rDNA 4. Sequence the 16S rDNA 5. Compare the 16S rDNA sequence with sequences of known organisms
A bacteriophage plaque assay is designed to enumerate phage particles. Place these steps in the correct order, starting with the host cell prep at the top.
1.Regular bacterial growth plates are prepared.2. Dilutions of viral samples is prepared.3. Host bacteria and dilution of viral sample are mixed in liquid soft-agar.4. Mixture is poured on top of plate and allowed to harden.5. Plates are incubated overnight.6. Circular zones of clearing in bacterial growth are observed and counted.
This figure shows the ribosomal components in prokaryotes. Which component is most often used in taxonomy?
16S rRNA
_______ move by extending and retraction portions of their cytoplasm.
Amoebae
Determining the phylogeny, or evolutionary relatedness, of members of which of the following groups would likely be the least difficult?
Animals
______ include medically important protozoa that are obligate intracellular parasites.
Apicomplexans
An organism found in an environment that is very hot and acidic is most likely a member of the domain
Archaea
Characterized members of the domain ______ typically thrive in extreme environments, such as high heat, acidity, alkalinity, and salinity.
Archaea
In which phase of the T4 phage lytic cycle are new phage particles put together?
Assembly
Which of the following describes the various viral parts coming together to produce virions?
Assembly
Which of the following genera of endospore formers include both obligate aerobes and facultative anaerobes?
Bacillus
The two most common genera of Gram-positive rod-shaped bacteria that form endospores are ______.
Bacillus Clostridium
______ species are Gram-negative, strictly anaerobic, make up about a third of the bacteria in fecal matter in humans, and are associated with abscesses and bloodstream infections.
Bacteroides
____species are Gram-negative curved rods that are highly motile and prey on other Gram-negative rods by boring a hole in their cell wall.
Bdellovibrio
Which of the following viral release methods may not initially destroy the cell?
Budding
Most bacteria that grow in the presence of O2 are which of the following?
Catalase-positive
Match the organism with the disease that it causes.
Chlamydia trachomatis- A common sexually transmitted disease Chlamydophila pneumoniae- Atypical pneumonia Chlamydophila psittaci- Psittacosis
Which type of viral infection is characterized by the continuous, low-level production of new virus particles by animal host cells?
Chronic
Which of the following are sources of plant viruses?
Contaminated seeds Insects Soil Contaminated pollen
Which of the following are diseases caused by prions?
Creutzfeldt-Jakob disease Bovine spongiform encephalopathy Scrapie
Apicomplexans include which of the following genera of protozoa?
Cryptosporidium
You are attempting to identify a bacterium that you are unable to culture in lab. Which set of techniques would best help you attempt to identify this bacterium?
DNA amplification followed by rDNA sequencing
Viral genomes can be
DNA or RNA Single- or double-stranded
The nucleocapsid is composed of
DNA or RNA and protein.
When a new protozoan is discovered, the best way to determine how closely related it is to other protozoa is to look at its ______.
DNA sequence
Molecular techniques such as ______ have allowed scientists to determine the phylogeny of microorganisms.
DNA sequencing
The replication strategies of animal viruses can be divided into three general categories: those used by ____-viruses, ________ viruses, and reverse transcribing viruses.
DNA, RNA
Algae are a direct cause of disease in humans.
False
DNA viruses can only replicate when the host cell is replicating its own genome.
False
Fungi are usually only found in harsh environments like hot springs and in the deep ocean.
False
It is easier to cultivate animal viruses than bacteriophages.
False
Many fungi cause diseases in humans.
False
Organisms cannot be identified unless they can first be cultivated.
False
The three-domain system has always been used as the standard classification system for organisms.
False
Lysogens are more susceptible to reinfection by the same type of phage.
False, Lysogens are immune to superinfection.
When a bacterial culture is infected with a temperate phage, all particles of the phage will lysogenize their host.
False. Some particles will enter the lytic cycle.
Which of the following phage types cause productive infections that do not kill the host cell?
Filamentous
Mycology is the study of ______.
Fungi
Which of the following explains why mildew and mold are such a problem in damp basements?
Fungi are most successful in moist environments.
Which form of transduction results from packaging errors during phage assembly?
Generalized
Replication of temperate phages and lytic phages have which steps in common?
Genome entry Release Attachment Biosynthesis of viral components Assembly
_______ is a cyst-forming flagellate that lives in the intestinal tract, and is a leading cause of diarrhea worldwide.
Giardia lamblia
Members of the family Enterobacteriaceae are _______.
Gram-negative rods
Spirochetes are bacteria that are ______ and possess a unique mechanism of _______.
Gram-negative; motility
Endospore-forming bacteria are typically ______.
Gram-positive rods
_______ are a group of flagellated protozoa that multiply by binary fission. They live in the bloodstream for part of their life cycle, and all require a blood-feeding insect as part of that cycle.
Hemoflagellates
Which are the two main criteria used in classifying viruses?
Host range Genome structure
Fungi cause human illnesses in three general ways. Match each term with its definition.
Hypersensitivity reaction: Person develops an allergic or asthmatic reaction to fungal components. Infection: Fungus grows on or in the human body, causing mycosis. Intoxication: Fungus produces a toxin the person ingests.
Which of the following are the three general shapes of most viruses?
Icosahedral Complex Helical
Which of the following statements about prions are true?
Infectious prion proteins have a different shape from normal prion proteins. Infectious prion proteins are insoluble and aggregate in brain tissue. Infectious prion proteins may convert normal prion proteins into an abnormal form.
How does bacteriophage nucleic acid enter the host cell?
Injection
Why are bacteriophages easier to study than animal viruses?
It is easier to grow the bacteriophage host cells in the lab.
Which of the following about classifying viruses is FALSE? Viruses can be classified based on different viral characteristics. It provides a useful way to identify and study viruses. An online database classifying viruses is kept by the ICTV (International Committee on Taxonomy of Viruses). It is not as important as classifying organisms since they are not living entities
It is not as important as classifying organisms since they are not living entities.
Antibiotics that interfere with peptidoglycan synthesis are ineffective in the treatment of _______ infections because these organisms lack a cell wall.
Mycoplasma
Medically-significant members of the genus Neisseria include which of the following?
N. meningitidis N. gonorrhoaeae
Members of the genus __________ are causative agents of gonorrhea and meningitis.
Neisseria
Which of the following genera of organisms forms a beneficial symbiotic relationship with plants?
Rhizobium
Which of the following correctly describe relationships between genera of bacteria and their means for obtaining nutrients from plants?
Rhizobium species form a mutually beneficial relationship with certain types of plants. Agrobacterium species are plant pathogens that cause tumor-like growths.
Why are ribosomal components (ribosomal RNA and ribosomal proteins) considered reliable indicators of evolutionary relatedness?
Ribosomal genes are not commonly horizontally transferred. Ribosomes are present in all organisms. Ribosomes perform crucial and functionally constant tasks.
Which of the following is considered the most reliable indicator of evolutionary relatedness in prokaryotes?
Sequences of ribosomal components
The designation O157:H7 of E. coli is an example of which of the following?
Serological typing
Which form of transduction results from excision errors during the transition from a lysogenic to lytic cycle?
Specialized
___________ transduction is the result of excision errors made as temperate phages transition from a lysogenic to a lytic cycle.
Specialized
Which of the following bacteria is typically a harmless resident of the skin?
Staphylococcus epidermidis
You isolate an organism from the soil. If it turns out to be an aerobic Gram-positive rod that resembles a fungus in its pattern of growth, then it most likely belongs to the genus ______.
Streptomyces
Some protozoan species can exist as a trophozoite or as a cyst form. How are these forms best described?
The cyst is an infectious survival form. The trophozoite is a growing, feeding form.
More than 300 cases of salmonellosis occur within a large city. Each time, Salmonella enterica is isolated from the feces of the patient. Based on that information, the news media report that there must be a common source to all these cases. What additional information would be needed to support or disprove this view?
The specific strain of the Salmonella would need to be identified.
Which of the following statements about viruses are true?
The viral capsid is composed of protein. Viruses contain RNA or DNA but not both.
Why are sequences of ribosomal RNA so useful in microbial classification and identification?
They allow identification without culturing the organism. The sequences are relatively stable, since the ribosome would not function with too many mutations. Once a sequence is determined, it can be compared with sequences of known organisms by searching extensive databases.
Which of the following statements regarding amoebae is FALSE?
They are differentiated by the size of their mitochondria.
Which of the following accurately describe biochemical tests used to identify microorganisms?
They rely on differences in metabolic capabilities of microorganisms. They generally provide a more certain identification than just relying on colony morphology.
Human cells are larger than viruses by which size factor?
Thousand
All algae contain chlorophyll ______.
a
Replication of single-stranded DNA viruses is quite similar to that of double-stranded DNA viruses, except that ______.
a complement to the single-stranded DNA molecule must be synthesized
A prion is best described as ______.
a proteinaceous infectious agent
The purpose of the different types of chlorophyll is to ______.
absorb light of different wavelengths
Cyanobacteria living in aquatic environments can ______.
accumulate in larger numbers, which is referred to as a bloom move vertically through a water column using gas vesicles
A special staining procedure called the ______ is used in the identification of Mycobacterium species.
acid-fast stain
Infections that have a sudden onset of symptoms of relatively short duration are described as
acute
Infections that have a sudden onset of symptoms of relatively short duration are described as _________ infections.
acute
The fungal hyphae that grow up in the air and produce reproductive spores are called _________ hyphae.
aerial
Fungi associate with ______ to form lichens.
algae and cyanobacteria
Simple photosynthetic eukaryotes are collectively described by the term ______
algae or alga
Bdellovibrio species ______.
are highly motile Gram-negative curved rods prey on Gram negative bacteria like E. coli bore a hole in the cell wall of their prey
In single-stranded (-) RNA viruses, the enzyme replicase is important because it uses (-) RNA ______.
as a template to make (+) RNA, which can be used for protein synthesis
The majority of medically important fungi are members of what phylum?
ascomycota
Budding is a type of _______ reproduction that occurs in _______.
asexual; yeast
During the _____ or maturation step in viral multiplication, capsids and genetic material are packaged into virions.
assembly
Phage components are put together into mature virions during the _________ step of the lytic cycle.
assembly
Phage components are put together into mature virions during the __________ step of the lytic cycle.
assembly
The _________ or maturation stage of the T4 phage lytic cycle is marked by the formation of new phage particles inside of the host cell.
assembly
The binding of a bacteriophage surface protein to a host cell receptor is called ______.
attachment
List the steps of an animal virus infection cycle in the correct order. Start with the earliest at the top.
attachment, penetration, uncoating, gene expression and replication, assembly, and release.
Viruses that infect bacteria are called
bacteriophages
Certain bacteria that form symbiotic relationships with specific types of fish and squid are ______, meaning they emit light.
bioluminescent
Infectious agents that have a simpler structure than viruses include ______.
both viroids and prions
Kelp "underwater forests" are aggregates of multicellular ______.
brown algae
In general, yeast cells reproduce asexually by a mechanism called
budding
The number of phage particles released from a host cell is called the _______ size.
burst
The ______ refers to the number of viruses released from each infected cell.
burst size
Myxobacteria fulfill an important role in nature ______.
by digesting bacteria by digesting certain fungi and algae as degraders of complex organic substances
In higher organisms such as plants and animals, the basic taxonomic unit of species is considered to be organisms that ______.
can interbreed to produce fertile offspring are morphologically similar
Animal viruses
can only be grown in animal cells
Sulfur-oxidizing bacteria ______.
can sometimes grow in filaments can use hydrogen sulfide or thiosulfate as an energy source
The viral genome is protected from the environment by a protein shell called the ______.
capsid
A viral capsid is made up of subunits called ______.
capsomeres
The capsid of a virus is composed of precisely arranged identical protein subunits called
capsomeres
Oncoviruses are viruses that can ______.
cause cancer in humans
Although live animals and fertilized chicken eggs have been used to cultivate animal viruses in the past, these have now been largely replaced by _________ culture
cell
Tumors are abnormal growths that result from a malfunction in the regulation of ______.
cell growth
A key characteristic of the genus Mycoplasma is that they lack a ________ , instead usually relying on sterols in their membrane to provide strength and rigidity.
cell wall
All of the following are true of hyphae EXCEPT ______.
cells in hyphae reproduce by binary fission
In general, algae have rigid cell walls mostly composed of _______.
cellulose
Algae conduct photosynthesis within organelles called
chloroplasts
The hepatitis B virus sometimes causes an infection that results in a continuous and low-level production of virus particles. This type of infection pattern is specifically described as a(n)
chronic
Asexual reproductive cells of fungi are typically called ______.
conidia
The term ______ is generally used to refer to the asexual reproductive cells of molds.
conidia
Fungi and water molds are good examples of __________- evolution because they both developed similar characteristics independently as a result of adaptation to similar environments.
convergent
Photosynthesis in algae occurs in chloroplasts. These organelles evolved from ancestors of modern-day _______.
cyanobacteria
Campylobacter jejuni infections are commonly associated with ______.
diarrhea
Microscopic algae characterized by the presence of silica-containing external structures called frustules, are known as
diatoms
Algae with different pigments can live at ______.
different depths
A fungus that can grow as single yeast cells or multicellular hyphae, depending on environmental conditions, is said to be a(n) _______ fungus.
dimorphic
Mutations in the influenza virus genome can result in minor changes in key viral surface proteins. This type of variation is called antigenic
drift
If viruses are present in high enough concentrations in a sample, they can be quantified directly using a(n)
electron
Methods for cultivating animal viruses include ______.
embryonated chicken eggs tissue culture
The process by which a virus is taken up by a host cell as a result of the host cell's cytoplasmic membrane surrounding the virion to form a vesicle is called ______.
endocytosis
Of the various types of dormant cells, the ______ is the most resistant to environmental extremes.
endospore
The phospholipid bilayer found surrounding the capsid of some viruses is the ______.
envelope
Which types of viruses are released by budding?
enveloped viruses
The virus that causes COVID-19 is _______, and phages are typically _______.
enveloped; non-enveloped
A target for many antifungal medications is ___________ because it can be found in fungal cell membranes, while animal cell membranes instead contain cholesterol.
ergosterol
Algae _______ an organized vascular system and possess relatively _______ reproductive structures.
lack; simple
A viral infection in which the viral genome is integrated into an animal host cell chromosome, yet can reactivate to cause a productive infection, is categorized as a(n)
latent infection
Enveloped viruses have an outer layer made up of _______.
lipid
In the laboratory, for quick identification of fungi, it is most practical to ______.
look at the asexual reproductive forms
The term __________ is used to describe the rupture or bursting of a bacterial cell following a phage infection.
lysis, cytolysis, or release
A ______ infection results from the integration of bacteriophage DNA into the chromosome of the bacterial host.
lysogenic
Some pathogenic bacteria produce toxins that are encoded on prophage DNA, and these are examples of __________ conversion.
lysogenic
Consequences of lysogeny include ______.
lysogenic conversion immunity to superinfection
Infection of bacteria by __________phages always ends with the lysis of the host cell.
lytic
In enveloped viruses, sandwiched between the nucleocapsid and the envelope is the ______.
matrix protein
Despite traditional groupings of protists, ultrastructure and DNA sequencing data reveal that protozoa using the same mode of locomotion ______.
may not be closely related
Fungi are characterized by ______.
membranes that contain ergosterol cell walls that contain chitin
Outside of living cells, viruses are
metabolically inert
Species of Campylobacter and Helicobacter are ______.
microaerophilic curved, Gram-negative rods
The orange shown here is spoiled by a morphological form of fungus called a(n)
mold
Filamentous fungi are called
molds
In terms of susceptibility to soaps, detergents, and disinfectants, enveloped viruses are ______ non-enveloped viruses.
more susceptible than
The terms yeast, mold, and mushrooms refer to fungal _______.
morphology
Viruses that can cause cancer in humans are known as ________ viruses
oncogenic, oncoviruses, or onco
Viruses that specifically target and kill cancer cells are called
oncolytic
A problem encountered in primary cultures derived from normal tissue cells is that cells will ______
only divide a limited number of times
In latent infections, the virions are ______.
only produced following reactivation
Facultative anaerobes preferentially use aerobic respiration if ________ is present.
oxygen
Plant viruses initially gain entry to host cells by ______.
passing through wounds in the host cell wall
infections remain for years, or even the lifetime of the host, sometimes without any symptoms.
persistent
All of the following are examples of the commercial contributions of fungi EXCEPT ______. production of toxins which can cause human disease synthesis of antimicrobial medications genetically engineered to produce medically important molecules use as model systems for the study of eukaryotic processes
production of toxins which can cause human disease
RNA viruses have a higher mutation rate than DNA viruses because replicases typically lack _______ ability
proofreading
In a lysogenic infection, the phage DNA that is incorporated into the bacterial host genome is called a ______.
prophage
The __________ bacteria have projections called prosthecae, which are extensions of the cytoplasm and cell wall that increase the surface area to facilitate absorption of nutrients.
prosthecate
The purpose of the sheath in sheathed bacteria is for ______.
protection
A capsid is ______.
protein coat that surrounds the viral genome
are defined as being unicellular heterotrophic eukaryotic organisms that are not fungi.
protozoa
Match the microscopic eukaryote with its appropriate description.
protozoa- heterotrophic unicellular organisms that are not fungi algae- simple autotrophic (photosynthetic) eukaryotes protists- a catch-all category of eukaryotes that are usually single-celled and are not fungi, plants, or animals
Life-threatening fungal infections are _______ in healthy people and more _______ in those that are immunocompromised.
rare; common
The stage of viral multiplication at which budding occurs is ______.
release
The enzyme of RNA viruses that typically lacks proofreading ability and thus makes many mistakes compared to the polymerases of DNA viruses is ______.
replicase
The virally encoded polymerase needed for replication of RNA viruses is called a
replicase
By definition, obligate intracellular parasites cannot ______.
replicate outside of a host cell
To maintain the lysogenic state, a _________ protein prevents expression of the gene required for excision.
repressor
Obligate aerobes obtain energy using ____________exclusively; none of them can ferment.
respiration
HIV is described as a _________ because it uses reverse transcriptase to make a DNA copy from its RNA genome.
retrovirus
Viruses that have an RNA genome and use reverse transcriptase to synthesize a DNA copy of that genome are called ______.
retroviruses
An enzyme that uses an RNA molecule as a template to make a complementary copy of DNA is called
reverse transcriptase
Reassortment of gene segments that encode viral surface proteins recognized by the immune system can result in a loss of the immune system's ability to recognize and respond to the virus. This phenomenon is called antigenic
shift
Staphylococcus epidermidis is part of the normal microbiota of the
skin
In ___________ transduction, only bacterial genes adjacent to the prophage can be transferred.
specialized
__________ transduction is the result of excision errors made as temperate phages transition from a lysogenic to a lytic cycle.
specialized
Attachment of animal viruses to the host cell typically occurs by means of ______.
spikes
The viral proteins that stick out from either the lipid bilayer of enveloped viruses or the capsid of non-enveloped viruses, and attach to host cells, are ______.
spikes
Many animal viruses have proteins called _______ that attach to receptors on host cells.
spikes, spike, or spike proteins
A group of Gram-negative bacteria has a spiral shape and a unique motility mechanism that allows them to move through thick, viscous substances. This group is called the
spirochetes
The dermatophytes are examples of what types of fungi?
superficial fungi
The photosynthetic partner in a lichen ______.
supplies organic compounds
Phage DNA and proteins are made during the _________ step of the T4 lytic cycle.
synthesis
Certain types of protozoa produce a growing feeding form called a(n) _______, and an infectious survival form called a _______.
trophozoite; cyst
Because of their ability to multiple indefinitely in vitro, established cell lines are made up of ______ cells.
tumor
Humans infected with Helicobacter pylori may develop peptic _______
ulcer
Algae can be ______.
unicellular or multicellular
The type of hyphae that anchor a mold and absorb nutrients are referred to as ______ hyphae.
vegetative
Before enveloped viruses bud from a host cell, specific viral proteins insert into the host membrane. These proteins become ______.
viral spikes
A _______ is a single virus particle.
virion
A complete viral particle, which typically consists of nucleic acid surrounded by a protein coat, is called a(n) ______
virion
A(n) _________ is an infectious agent that lacks a capsid and consists only of RNA.
viroid
Bacteriophages that exit the host cell at the end of an infection by lysing it are called _______ phages.
virulent
Single-celled fungi are ______.
yeast
This photomicrograph shows a tissue infected with a morphological form of fungus called a(n)
yeast
Signs of viral infections in plants include ______.
yellowing of leaves stunted growth presence of tumors
In taxonomy, the most useful rRNA molecule is the ______________ rRNA in prokaryotes and the ______________rRNA in eukaryotes.
Blank 1: 16S Blank 2: 18S
Which of the following help to explain why it is more difficult to determine the phylogeny of prokaryotes than that of plants and animals?
Prokaryotes have few differences in size and shape. The definition of species does not apply to prokaryotes in the same way as it does to plants and animals
What is the basic unit of taxonomic classification?
Species
A strain is ______.
one of a group of related isolates within a species
The cytoplasmic membrane lipids of members of the domain _________ are composed of hydrocarbons (not fatty acids) linked to glycerol by ether linkage.
Blank 1: Archaea or archaean
Taxonomic categories include _____which is defined as a grouping of similar families, and _________ which is a grouping of similar classes.
Blank 1: order Blank 2: phylum or division
For the scientific name Staphylococcus aureus, Staphylococcus has which of the following designations?
Genus
During photosynthesis, anoxygenic phototrophs use _______ as a source of electrons to make reducing power.
H2S
Why are sequence comparisons of the DNA coding for ribosomal RNA (rRNA) so useful in placing organisms on a phylogenetic tree?
Horizontal transfer of rDNA is rare Regions of rDNA are highly conserved. rDNA is present in all organisms.
Starting with the most general and ending with the most specific, which is the correct order for taxonomic units?
Kingdom, phylum, class, order, family, genus, species
Choose the methods used to identify prokaryotes that are based on phenotypic characteristics.
Metabolic capabilities Culture characteristics Microscopic morphology
You are working in a clinical lab and are given a stool sample to analyze for suspected roundworms. What phenotypic characterization approach would give you the fastest presumptive answer?
Microscopic morphology
A reason why environments that are routinely exposed to O2 can support anaerobic growth is that ______.
O2-consuming organisms depletes the oxygen levels
Choose the correct descriptions of serological tests.
Require detection by antibodies. Rely on differences of surface structure molecules such as components of the cell wall, capsule, flagella, or pili.
Colony morphology can give hints as to the identity of the organism. Match the following examples of specific morphological features with the correct organism.
Serratia marcescens- often red when incubated at 22oC Pseudomonas aeruginosa- has a distinct fruity odor; often produces a soluble greenish pigment Streptococcus pyogenes- forms β-hemolytic colonies on blood agar
The image shows results of the urease test. What does the positive result (pink tube on the left) tell us about the organism?
The organism produces urease, which degrades urea to CO2 and ammonia, increasing the pH of the medium to produce a color change in the indicator.
In addition to being photosynthetic, many cyanobacteria have the ability to convert nitrogen gas (N2) into ______, a process known as nitrogen fixation.
ammonia
Chemoorganotrophs that perform ______ often use sulfur or sulfate as a terminal electron acceptor.
anaerobic respiration
Which of the following were likely the earliest photosynthesizing organisms?
anoxygenic phototrophs
Most of the anaerobic chemolithotrophs that have been discovered are members of what domain?
archaea
Nitrifiers can be described as bacteria that ______.
are Gram-negative obtain energy by oxidizing inorganic nitrogen compounds such as ammonium or nitrite
Cyanobacteria as a group are capable of ______.
both photosynthesis and nitrogen fixation
Before molecular techniques were available, bacteria were often classified based on ______.
cell wall type ability to degrade different compounds
In a clinical lab, microscopic examination of a specimen is often enough to diagnose ______ because of their size and characteristic shape.
certain infections by eukaryotic parasites
Taxonomy can be viewed as three separate but interrelated areas. Match these three areas with their definitions.
classification - arrangement of organisms into groups (taxa; s., taxon) nomenclature - assignment of names to taxa identification - determination of taxon to which an isolate belongs
All of the following information can generally be determined from microscopic examination of a microorganism EXCEPT ______. identifying the size and shape of the microorganism identifying the microorganism as a prokaryote, fungus, or protozoan definitively determining the genus and species of the microorganism determining the organism type (e.g., yeast, roundworm) in cases when the causative agent is suspected (e.g., in vaginal secretions, stool samples)
definitively determining the genus and species of the microorganism
In order to distinguish different strains of bacteria, an antibiogram relies on ______.
differences in susceptibility to various antibiotics
Which of the following taxonomic designations is inclusive of all the others listed? kingdom family domain phylum order
domain
Members of the Gram-negative genera Aquifex and Hydrogenobacter are hydrogen-oxidizing bacteria. An example of their metabolism involves using ______.
hydrogen as a source of energy and oxygen as a terminal electron acceptor, forming water
Choose the properties that are representative of members of the domain Eukarya.
introns cell membranes that contain fatty acids linked to glycerol by an ester linkage membrane-bound nucleus
In 2019, 137 reported cases of diarrheal disease involved a specific strain of Salmonella enterica that was linked to consumption of pre-cut melons. This led to a recall of the products by the supplier. Why was it important to identify the specific strain in order to limit this outbreak?
knowing the strain made it possible to link these 137 cases in order to identify the source
Choose the pair of phrases that best completes the following scenario: Consider two organisms that diverged from a common ancestor at some point in history. If there are many differences in the sequences of their DNA, this indicates they diverged ______: if there are few differences, this indicates they diverged ______.
longer ago; more recently
According to the rules of nomenclature, the name of a bacterium or archaeon ______.
needs to include a Latin suffix can honor a scientist can reflect the habitat of the organism
A diverse group of Gram-negative bacteria that obtain energy by oxidizing inorganic nitrogen compounds such as ammonium or nitrate are known as
nitrifiers
Many cyanobacteria can convert nitrogen gas (N2) to ammonia, which is a process called ______.
nitrogen fixation
Hydrogen-oxidizing bacteria such as Aquifex and Hydrogenobacter are ______.
obligate chemolithotrophs Gram-negative thermophilic
Chemoorganotrophs oxidize ________ compounds such as glucose to obtain energy.
organic
Serological typing distinguishes different bacterial strains based on characteristics of which of the following?
proteins and carbohydrates such as those that make up flagella, capsules, and lipopolysaccharide molecules
MALDI-TOF mass spectrometry is an important new technology in bacterial identification because it can identify an organism from a colony ______.
rapidly, often in less than 15 minutes based on the profile of its proteins
For characterizing strain differences among prokaryotes, whole genome sequencing (WGS) has now largely replaced _______.
restriction fragment length polymorphisms (RFLPs).
All of the following are examples of biochemical tests EXCEPT one. Which?
serology Reason: Serology actually relies on the binding of specific antibodies to characteristic proteins or polysaccharides that make up a prokaryote, not on specific metabolic capabilities. gelatinase Reason: Recall that the suffix -ase indicates an enzyme; the gelatinase test detects the enzymatic breakdown of gelatin to polypeptides. oxidase Reason: Remember, the oxidase test is a biochemical test for the activity of cytochrome c oxidase, a component of the electron transport chain of specific organisms. catalase Reason: Recall that the catalase test detects the activity of catalase, an enzyme that breaks down hydrogen peroxide to form O2 and water. sugar fermentation Reason: Remember, sugar fermentation tests detect the ability of microbes to ferment a given sugar, which is a metabolic capability and a very commonly used test.
Scientists group bacteria into different groups in order to ______.
show how different species are related
Microscopic examination is important in the presumptive identification of an organism because it can provide information on the organism's ______.
size and shape staining characteristics
A group of closely related strains or individuals comprises a taxonomic category called
species
