Micro Final Flashcards
Contamination with ________ is a concern because they are highly resistant to killing.
endospores
The ________ are the largest known group of archaea.
methanogens
Cyanobacteria carry out the reactions of nitrogen fixation in specialized cells called
heterocysts
Members of the genus ________ are Gram-positive bacteria that show a distinctive process for cell separation known as “snapping cell division”, form an arrangement known as “palisades”, and cause the disease diphtheria.
Corynebacterium
Which of the following diseases is NOT associated with bacteria that form endospores?
tuberculosis, anthrax, botulism, gangrene, tetnus
tuberculosis
Which bacterial genera produce(s) endospores?
Bacillus and Clostridium
Which of the following bacterial genera includes species that protect areas of the body such as the intestinal tract and the vagina from invasion by pathogens?
Lactobacillus
Members of which of the following genera are the most common sexually transmitted bacteria in the United States?
Chlamydia
A flexible, spiral, corkscrew-shaped bacterium is called a
spirochete
A Gram-positive rod-shaped ________ is a frequent contaminant of dairy products and meat and can cause fatal newborn meningitis.
Escherichia coli
A _______ is a slightly curved rod.
vibrio
What is a pleomorphic prokaryote?
a prokaryote whose cell morphology varies in shape and size
Which of the following is NOT a means of reproduction in prokaryotes?
binary fission, meiosis, snapping division, budding
meiosis
What is the difference between spores and endospores?
spores are reproductive structures and endospores are stable resting structures
________ form when planes of cell division are random.
staphylococci
Which of the following is NOT a taxonomic domain?
protista, archea, bacteria, eukarya
protista
Scientists classify prokaryotes based on similarities in _______.
DNA, RNA, protein sequences
all of the above
Which statement BEST describes the extent of our current knowledge of prokaryotes?
most prokaryotes have never been isolated or cultured
Why are rRNA gene sequences an excellent tool for classifying bacteria?
genes are present in all known bacteria, part of the gene sequence is highly conserved, and part of the gene sequence varies from species to species
Which statement MOST accurately describes the taxonomy of bacteria described in Bergey’s Manual?
bacteria are classified based on the consensus opinion of experts at a particular point in time
Which of the following is NOT a difference between bacteria and archaea?
all archaea are extremophiles
What is an extremophile?
a microbe that requires extreme conditions of temperature, pH, and/or salinity to survive
How would you classify a microbe that requires temperatures over 80° C for growth?
hyperthermophile
An organism that requires an environment containing greater than 9% NaCl would be considered a ________.
halophile
Methanogens are obligate anaerobes that _______
convert CO2, H2, and organic acids into CH4
Which answer best describes “deeply branching bacteria”?
Microbes that appear to be similar to the earliest bacteria
An autotrophic bacterium ________.
produces organic compounds from carbon dioxide
How are phototrophic bacteria classified?
based on their pigments and sources of electrons for photosynthesis
According to the endosymbiotic theory, which group of phototrophic bacteria is MOST likely to have given rise to chloroplasts present in plants?
cyanobacteria
What is nitrogen fixation?
the reduction of nitrogen gas to ammonia
If organism X has a G + C content of 60% and organism Y has a G + C content of 35%, which of the following is most likely?
they are not closely related
Which of the following is a unique characteristic of mycoplasmas?
they lack cell walls
Which of the following does NOT have a high G + C content?
lactobacillus
Which of the following is NOT a characteristic of Corynebacterium?
they have a low G + C content
Which of the following is NOT a characteristic of the betaproteobacteria?
they are similar to alphaproteobacteria according to rRNA
Which of the following is NOT a characteristic of pseudomonads?
they are in the deltaproteobacteria group
Host specificity of a virus is due to
interactions between viral and cellular surface molecules
Which of the following lists stages of a lytic replication cycle in order, from earliest to latest stages?
I. Synthesis
II. Assembly
III. Attachment
IV. Release
V. Entry
III, V, I, II, IV
A ________ is a bacterial virus which is integrated into the host cell DNA.
Prophage
Reverse transcriptase is associated with which of the following?
retroviruses
Naked capsid animal viruses are commonly released from the infected cell by ________, a process the host cell does not survive.
lysis
A lipid membrane is present in which of the following?
enveloped viruses
Which virus produces a rash and permanent scars on the skin, but has also been declared eradicated through mass vaccination?
Poxviridae
An older adult is complaining of an intensely painful rash that has appeared as a patch on one side of his chest. This description is consistent with
shingles
Diarrhea, nausea, and vomiting are signs and symptoms associated with which of the following viruses, particularly common in large gatherings of people like cruise ship vacations?
norovirus
Which vaccine-preventable disease caused by an RNA virus has been nearly eradicated?
polio
All of the following are characteristics of life EXCEPT _______
A. the ability to carry out metabolic processes
B. the ability to grow and respond to the environment
C. the ability to live in the presence of oxygen
D. the ability to independently reproduce
the ability to live in the presence of oxygen
acellular pathogens include _____, _______, ________
viruses, viroids, prions
A virion is composed of a ________
capsid surrounding a nucleic acid core
What is the size range of virus particles?
approximately 20 nm to 500 nm
________ are the proteinaceous subunits that make up the viral capsid.
capsomeres
What accurately describes lytic viral replication?
viral replication usually results in the death and lysis of the host cell
What are 3 ways that viruses can cause human cancer?
Viruses can carry copies of oncogenes, promote/activate host cell oncogenes, and interferes with tumor suppressor genes
The period of time required to complete the lytic cycle is called _______
the burst time
How is the T4 virus able to penetrate the cell wall of E. coli?
it releases lysozymes, which weakens cell walls
If one virus particle infects a cell, approximately how many infectious virus particles are present during the synthesis step of the virus replication cycle?
0
What is the difference between phage T4 and lambda phage?
phage T4 uses lytic replication and lambda follows lysogenic replication
A prophage is _______
a copy of the viral genome inserted into the host cell chromosome
_______ may result in induction of prophage.
damage to the host cell’s DNA
Can a lysogenic virus ever switch to the lytic replication cycle?
Yes, but it can switch only after the viral DNA is excised from the host genome by induction
A distinguishing characteristic of retroviruses is ______
they carry reverse transcriptase within their capsid
_____, _______, ______ are used to culture animal viruses?
cultured cells, embryonated chicken eggs, and mature animals
______ is a common and relatively inexpensive method for estimating numbers of phage.
a plaque assay
What is the BEST method to use when attempting to culture bacteriophages?
mix the phages with bacteria in a liquid media and pour over an agar plate
Diploid cell cultures can be derived from ______, _______, ______ cells.
embryonic animal, plant, and human
How do scientists introduce virus particles to the inside of a chicken egg?
the virus particles are injected directly into specific embryonic tissues within the egg
What are viroids?
small circular pieces of ssRNA that are infectious to plants
How are viroids different from viruses?
viruses produce proteins and viriods produce free RNA that lack a protein coat
What is a prion?
a proteinaceous infective particle
How do disease-causing prions produce more disease-causing prions?
They change the shape of cellular PrP
Prion diseases of the brain are called _______
spongiform encephalopathies
What is an accepted argument for why viruses should be considered living?
They possess genomes with instructions for replicating themselves
Merozoites are a result of
schizogony
single-celled eukaryotes lacking a cell wall are
protozoa
the ______ is the entire interwoven mass of one multicellular fungal organism
mycelium
hyphae are associated with what?
molds
lichens are composed of a symbiosis of fungi, ______, and _______
cyanobacteria, green algae
An elderly woman is experiencing fever, chest pain, difficulty breathing, and a cough that occasionally brings up mucus containing blood. She reports having visited family in rural New Mexico over the Labor Day weekend. A sample from her lungs shows the presence of large spherules. Which of the following is the most likely infecting agent?
Coccidioides immitis
What fungal infection was extremely rare prior to the AIDS epidemic?
Pneumocystis pneumonia
Which of the following is the most common parasitic disease in industrialized nations?
Trichomonas infection
After a trip to several South American countries, a middle-aged man becomes ill. He becomes anemic, loses weight, and runs a fever. The clinician notes a recently healed sore near his lip. The patient then seemingly improves and recovers. Several months later, the patient suddenly dies from congestive heart failure. What parasitic infection is considtent with this scenario?
leishmaniasis
Which of the following organisms can colonize the nasal cavity and enter the brain to cause meningoencephalitis?
Naegleria
