Unit 4

Which three of the following are physiological and metabolic characteristics useful in bacterial taxonomy?

Ability to grow on certain carbon sources Presence of carotenoid pigments Salt tolerance

Which of the following use the reductive acetyl-CoA pathway only for carbon assimilation and not energy conservation?

Archaea capturing energy using anaerobic respiration with sulfate as the terminal electron acceptor Certain anaerobic bacteria including planctomycetes, proteobacteria, and spirochetes

In which domain(s) is it difficult to define what a "species" is?

Bacteria Archaea

Which three are reason(s) that the concept of a species is not as defined in bacteria and archaea as in eukaryotes?

Bacteria and archaea lack extensive morphological features. Bacteria and archaea lack an extensive fossil record. Bacteria and archaea lack sexual reproduction.

Which two of the following characteristics apply to tamiflu?

Blocks release of new viruses from host Inhibits neuraminidase

Which three of the following are functions of reverse transcriptase?

DNA-dependent DNA polymerase Ribonuclease RNA-dependent DNA polymerase

Which two of the following statements are true?

Fungal cells are more similar to human cells than to bacterial cells. Currently there are fewer antifungal agents than antibacterial agents.

Which two of the following genes are a part of the core genome?

Gene encoding a ribosomal protein Gene encoding the sigma subunit of RNA polymerase

Which of the following biochemical differences confirm the distinction between bacterial and archaeal lineages first proposed by Woese and Fox in their analysis of small subunit rRNA sequences?

RNA polymerase structure membrane lipids cell wall structure

What must all negative-strand RNA viruses bring into the host cell?

RNA-dependent RNA polymerase

Induction of phage λ occurs when environmental factors cause DNA damage that alters the activity of ______.

RecA

The DNA sequence of which gene or genes has been the most useful in identifying and constructing the phylogenies of microorganisms?

SSU rRNA

Decreasing levels of λ repressor can result in ________.

excision of the prophage from the host chromosome

The anaerobic autotrophic archaea use __________ rather than NADPH as a source of electrons.

ferrodoxin

Acyclovir blocks the activity of viral

herpes simplex

Which proteins are used by bacteriophage T4 for release from host cells?

holin lysozyme

What does reverse transcriptase use as a primer in the initial steps of DNA synthesis?

host tRNA

Small subunit rRNA gene sequencing has become a method of choice for both

identification of microorganisms to the genus level inferring the phylogeny of microorganisms

The HIV proviral DNA is inserted into host DNA by ______.

integrase

The enzyme that catalyzes the integration of the phage λ genome into the host cell chromosome is

integrase

The genome of bacteriophage ΦX174 is _______.

plus-strand DNA

Which two of the following are negative-strand viruses?

rabies virus Ebola

The process of a latent herpesvirus infection progressing to a productive infection is termed _____.

reactivation

Virus will attach to host cells via a viral ligand and a host

receptor

The parvovirus DNA replication method is often referred to as the _______ method.

rolling hair pin

The viral-encoded proteins that project from a viral envelope surface are called ____.

spike proteins

Which three of the following are characteristics of human parvovirus B19?

ssDNA genome Icosahedral shape Nonenveloped

Retroviruses have a genome that is composed of _______.

ssRNA

The difference between the life cycles of double-stranded DNA viruses and single-stranded DNA viruses is that _____.

synthesis of the second strand in ssDNA viruses must occur before replication and transcription

Enveloped viruses gain their envelope from ____.

the host membrane

In a phylogenetic tree, the length of a branch represents ________.

the number of molecular changes that have occurred between two nodes

Herpesviruses cause both productive and latent infections. In a latent infection, _____.

the viral genome remains in the cell, but new viruses are not produced

Nucleocytoplasmic Large DNA (NCLD) viruses are often termed megaviruses because _____.

they are large enough to be visible by light microscopy

"Type strains" are used in taxonomy for the following two purposes:

to "hold" the species name, ensuring its permanence during subsequent nomenclature revisions to serve as a comparison point for other similar strains

For plus-strand RNA viruses, the negative-strand RNA molecule is synthesized by _____.

viral RNA-dependent RNA polymerase

New copies of the HBV genome are created in the host cytoplasm by _____.

viral reverse transcriptase

Spikes, or peplomers, are _____.

virally-encoded proteins that project from the envelope surface

RecA-induced cleavage of λ repressor results in the increased transcription of which three genes?

xis cro int

The basis for identifying a new isolate and placing it in a phylogenetic context is _____.

comparison to standards and type strains

Eukaryotic signature proteins found in Asgard genomes include ______.

components of intracellular trafficking and secretion pathways cytoskeletal components such as actin and tubulin information processing proteins such as DNA polymerase and ribosome components

Nucleocytoplasmic Large DNA (NCLD) viruses perform the steps of their life cycle in the _____ of the host cell.

cytoplasm

The administration of a cocktail of anti-HIV agents at high dosages, called combination drug therapy, prevents the development of

drug resistance

In contrast to viral genomic DNA, which may be dsDNA, ssDNA, dsRNA, or ssRNA, cellular genomes are always _____

dsDNA

Most negative-strand RNA viruses are _____.

enveloped viruses that infect animals

The cII protein plays a primary role in determining if phage λ will ______.

establish lysogeny or follow the lytic pathway

Which pathway is not commonly used to fix carbon by archaeal autotrophs?

3-Hydroxypropionate bi-cycle

Carbon fixation by the reductive acetyl-CoA pathway in methanogens uses this enzyme to reduce carbon dioxide to carbon monoxide.

CO dehydrogenase

Regulation of appropriate phage λ genes for establishing the lytic and lysogenic cycles is facilitated by _____. [Choose two.]

Clustering of genes with a common function Coordinated transcription

Which two of the following conditions must be met before the genome of a retrovirus can serve as a template for the synthesis of mRNA and new positive-strand genome molecules

Conversion from positive-strand RNA to dsDNA Integration into host's DNA

Why is RNA-dependent RNA polymerase (RdRp) essential for every virus with an RNA genome?

Host cells have no enzyme to synthesize RNA from an RNA template.

What role does the cII protein play in the maintenance of the phage λ lysogenic state?

Increases transcription of cI

In genotypic classification, similarity of which two of the following is used as the basis to classify microorganisms?

Individual genes Whole genomes

Antiprotozoan drugs are NOT known to target which of the following?

Membrane synthesis

Which statement best describes the rationale behind combination drug therapy in HIV patients?

Minimizes the chance for drug resistance development

Which two of the following characteristics apply to antifungal agents?

Most are fungistatic Many are toxic to human cells

Which three of the following are characteristics of the polio virus?

Non-enveloped Plus-strand RNA genome Enters human host through ingestion

Which three of the following are characteristics of rotaviruses?

Nonenveloped Wheel shape RNA genome

Which five of the following are classes of drugs used to manage HIV infection?

Nucleoside reverse transcriptase inhibitors Fusion inhibitors Nonnucleoside reverse transcriptase inhibitors Integrase inhibitors Protease inhibitors

Which of the following is NOT a characteristic used for viral classification by the International Committee on Taxonomy of Viruses?

Pathologic and cytologic effects

Which group of RNA viruses has genomes that can act as a mRNA to be translated immediately upon release into the host cytoplasm?

Plus-strand RNA viruses

What effect does host protease degradation of cII have on the phage lambda lysogenic cycle?

Prevents entry into the lysogenic cycle

Which of the following is a characteristic for classifying viruses that is used by the Baltimore system but not the ICTV system?

Process of viral mRNA synthesis

Why are there fewer antiprotozoan drugs than antibacterial drugs?

Protozoa are eukaryotes and thus have fewer targets for drug action

True or false: The enzymes required for a single-stranded DNA virus to carry out its life cycle are the same enzymes used by the host cell, so that the virus does not need to synthesize its own DNA or RNA polymerases.

TRUE

Which of the following statements regarding an organism's G + C content is true?

The G+C content is the percentage of guanine and cytosine bases in an organism's DNA.

Which of the following is NOT a class of drug used to manage HIV infections?

Topoisomerase inhibitor

Which four of the following are characteristics considered by the ICTV for the purpose of viral classification?

Virion and capsid dimensions Symmetry of the capsid Presence or absence of an envelope Nucleic acid type

Parvovirus DNA replication involves ______.

a dsDNA intermediate

The influenza virus consists of _____.

a negative-strand RNA an envelope

The enyzme that catalyzes the first step in ammonia oxidation is ______.

ammonia monooxygenase

The Asgard archaea compromise a proposed superphylum encompassing four proposed phyla that ______.

are all named for characters that inhabit the kingdom of Asgard, described in Norse mythology were all discovered through metagenomics in surveys of aquatic sediments

Archaea can multiply by

binary fission budding fragmentation

What activator protein increases the transcription level of the phage λ int gene to promote lysogeny?

cII

Which phage λ-encoded protein protects cII from degradation by the host protease?

cIII

Which of the following is NOT a mode of action of chloroquine?

interferes with protein synthesis

Which of the following are targets of antifungal agents?

membrane synthesis

Prior to the recent classification of aerobic ammonia oxidizers as Thaumarchaeota, they were described as ______ crenarchaeota.

mesophilic

The recent classification of mesophilic crenarchaeota as Thaumarchaeota was on the basis of ______.

metagenomics

The reductive acetyl-CoA pathway is used for both carbon assimilation and energy conservation in ______.

methanogens

Multiplication in archaea can occur by all of the following methods EXCEPT ______.

mitosis

The genome of human parvovirus B19 is _____.

negative-strand DNA

Which statement best describes the structure of the HBV genome?

nicked, circular DNA

Which two of the following components make up a viral nucleocapsid?

nucleic acid protein coat