Microbiology W3-1

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Questions and Answers

Which of the following phyla of bacteria includes the class Gammaproteobacteria?

Bacteroidetes

Actinobacteria

Cyanobacteria

Proteobacteria (correct)

What is the significance of horizontal gene flow in Proteobacteria?

It shapes metabolic diversity. (correct)

It eliminates the need for genetic variation.

It limits metabolic diversity.

It promotes the development of gram-positive bacteria.

Which class of the phylum Proteobacteria is specifically associated with the order Pseudomonadales?

Epsilon-proteobacteria

Alphaproteobacteria

Gammaproteobacteria (correct)

Delta-proteobacteria

Which of the following traits is true for all members of the Proteobacteria phylum?

They are all gram-negative. Signup and view all the answers

Which of the following bacteria is classified under the phylum Cyanobacteria?

Microcystis Signup and view all the answers

What does the term 'protean' refer to in the context of Proteobacteria?

Highly adaptable in shape and function. Signup and view all the answers

What component forms the basis of Carl Linnaeus's classification system?

A hierarchy of ranks in ascending order Signup and view all the answers

Which of the following domains are included in the current classification of microorganisms?

Eukaryotes, Bacteria, and Archaea Signup and view all the answers

Bergey's Manual, which greatly influenced bacterial taxonomy, was primarily based on which analytical approach?

Gram staining and phenotypical properties Signup and view all the answers

Which feature was used by Carl Woese to classify the Eubacteria into different divisions?

16S ribosomal RNA sequences Signup and view all the answers

In the polyphasic approach to bacterial taxonomy, which method is NOT included?

Ecological analysis Signup and view all the answers

Which of the following is the correct classification order of the bacterium Escherichia coli?

Domain: Bacteria, Phylum: Proteobacteria, Class: Gammaproteobacteria Signup and view all the answers

What is the primary focus of systematics in biological studies?

Studying diversity and relationships among organisms Signup and view all the answers

Which of the following ranks in taxonomy comes directly after 'class' in Linnaeus's classification system?

Order Signup and view all the answers

What type of analysis primarily involves studying the genome in bacterial taxonomy?

Molecular analysis Signup and view all the answers

What is the significance of nucleotide sequence differences in phylogenetic analyses?

They are influenced by the number of mutations since the last common ancestor. Signup and view all the answers

Which method is typically used to obtain SSU rRNA for phylogenetic analysis?

Polymerase chain reaction (PCR). Signup and view all the answers

In the context of SSU rRNA, what do V1-V9 refer to?

Regions representing variations in primary structure. Signup and view all the answers

How does taxonomy assist in classification?

It organizes organisms according to evolutionary relationships. Signup and view all the answers

Which of the following is NOT a part of the taxonomic hierarchy?

Instinct. Signup and view all the answers

What can be inferred from analyzing environmental samples using metagenomics?

It allows for sequencing of SSU rRNA from mixed microbial populations. Signup and view all the answers

Why is the 16S rRNA gene considered important in phylogenetic analysis?

It is universally conserved and allows for broad comparisons. Signup and view all the answers

During classification, what does the term 'genus' refer to?

A group of several species. Signup and view all the answers

What key feature distinguishes the rRNA of Archaea from that of E. coli?

Archaea rRNA has numerous differences in primary structure. Signup and view all the answers

Which of the following describes the role of mutations in phylogenetic trees?

Accumulated mutations since divergence indicate evolutionary distance. Signup and view all the answers

Which statement about Salmonella enterica is correct?

It has more than 2,500 serotypes based on antigens. Signup and view all the answers

Which of the following diseases is NOT caused by Salmonella or Shigella?

Cholera Signup and view all the answers

What is the significance of the naming scheme for Salmonella enterica?

It allows identification of different serovars. Signup and view all the answers

Which characteristic is NOT true for Salmonella typhi?

It is a spore-forming organism. Signup and view all the answers

Who co-discovered Salmonella enterica?

Daniel Elmer Salmon alone. Signup and view all the answers

Which of the following genera is NOT part of the Enterobacteriaceae family?

Bacillus Signup and view all the answers

Which of the following orders is NOT classified under Alphaproteobacteria?

Actinobacterales Signup and view all the answers

What is a common characteristic of Rickettsiales?

They require host cells for growth. Signup and view all the answers

Which disease is NOT associated with Rickettsia?

Malaria Signup and view all the answers

What is a significant function of Wolbachia in insects?

Inducing parthenogenesis Signup and view all the answers

Which of the following is true about the interaction of Wolbachia with human health?

It has negligible risk when associated with mosquitoes. Signup and view all the answers

What is the primary ecological niche of Wolbachia species?

Inside insect cells Signup and view all the answers

Which of the following genera is best known for its role as an intracellular parasite of insects?

Wolbachia Signup and view all the answers

In terms of their nutritional requirements, many Alphaproteobacteria are characterized as:

Oligotrophic organisms Signup and view all the answers

Which of the following best describes Wolbachia's transmission within insect populations?

Through maternal transmission via eggs Signup and view all the answers

Which metabolic product is primarily associated with 2,3-butanediol fermentation in enteric bacteria?

2,3-butanediol Signup and view all the answers

Which of the following is a distinguishing feature of the Enterobacteriales group among Gammaproteobacteria?

Presence of flagella Signup and view all the answers

Which fermentation pattern do Escherichia, Salmonella, and Shigella primarily exhibit?

Mixed-acid fermentation Signup and view all the answers

Which class of Proteobacteria is known for its diverse metabolic and ecological characteristics?

Gammaproteobacteria Signup and view all the answers

What type of bacteria is characterized by being facultatively aerobic, gram-negative, and nonsporulating?

Enterobacteriales Signup and view all the answers

What is the result of the fermentation of glucose by enteric bacteria in mixed-acid fermentation?

Balanced production of CO2 and H2 Signup and view all the answers

Which order of Betaproteobacteria is known for its significant functional diversity?

Burkholderiales Signup and view all the answers

Which of the following genera is NOT classified under Enterobacteriales?

Staphylococcus Signup and view all the answers

Which type of fermentation is characterized by producing butanediol, ethanol, CO2, and H2 as primary products?

2,3-butanediol fermentation Signup and view all the answers

The oxidase test is primarily used to differentiate enteric bacteria from which other group?

Proteobacteria Signup and view all the answers

Which characteristic distinguishes typhoidal Salmonella from non-typhoidal Salmonella?

Is a strict human pathogen with no other reservoirs Signup and view all the answers

What are the common symptoms of typhoid fever caused by Salmonella Typhi?

Headaches and generalized body aches Signup and view all the answers

How can an individual become a carrier of Salmonella Typhi after an acute illness?

Via asymptomatic long-term colonization Signup and view all the answers

What significant role did Mary Mallon, known as Typhoid Mary, play in the study of typhoid fever?

She was the first identified asymptomatic carrier of the pathogen. Signup and view all the answers

In what manner is typhoid fever typically transmitted among individuals?

From contaminated food and water handled by a human carrier Signup and view all the answers

What differentiates the disease symptoms caused by non-typhoidal Salmonella from those caused by typhoidal Salmonella?

Non-typhoidal Salmonella produces milder disease symptoms. Signup and view all the answers

What is a key characteristic of Salmonella enterica serovar Paratyphi compared to Salmonella Typhi?

It leads to a milder form of typhoidal illness. Signup and view all the answers

Which genera is known for its role as a bacterial predator in the Deltaproteobacteria class?

Bdellovibrio Signup and view all the answers

What is the primary pathogenic effect of Campylobacter infection in humans?

Acute gastroenteritis Signup and view all the answers

Which trait is characteristic of Epsilonproteobacteria like Helicobacter and Campylobacter?

Microaerophilic metabolism Signup and view all the answers

What specific shape do young cultures of Helicobacter display?

Spirilla Signup and view all the answers

What is a potential long-term consequence of Helicobacter pylori infection?

Peptic ulcers Signup and view all the answers

Which order includes metal and sulfur-reducing bacteria within Deltaproteobacteria?

Desulfuromonadales Signup and view all the answers

Which characteristic is NOT associated with Helicobacter species?

Gram-positive Signup and view all the answers

What is a common condition that can arise from Helicobacter pylori colonization?

Gastric adenocarcinoma Signup and view all the answers

What is the primary method used by Helicobacter pylori to survive in the acidic environment of the stomach?

Urease production Signup and view all the answers

What is the most sensitive staining method for detecting Helicobacter species in gastric biopsy specimens?

Warthin-Starry silver stain Signup and view all the answers

Which features characterize Listeria monocytogenes?

Gram-positive, catalase-positive, motile Signup and view all the answers

How is Helicobacter pylori typically diagnosed in laboratory settings?

Histologic examination and urease activity testing Signup and view all the answers

What unique characteristic does the phylum Actinobacteria include?

Filamentous forms, including Streptomyces Signup and view all the answers

What is a common feature of the genus Mycoplasma?

Small cell size, lack of a cell wall Signup and view all the answers

Which method can serve as a reliable diagnostic test for Helicobacter pylori infection?

Urease test Signup and view all the answers

What environmental conditions can support the growth of Listeria monocytogenes?

Refrigerated conditions and a wide pH range Signup and view all the answers

What are the implications of a high urease activity in biopsy specimens for diagnosing Helicobacter pylori?

Indicates presence of the infection Signup and view all the answers

Which of the following accurately describes the growth characteristics of Listeria monocytogenes?

Can proliferate at refrigeration temperatures Signup and view all the answers

What form does Chlamydia take when it is in an infectious state?

Elementary body Signup and view all the answers

Which process follows the phagocytosis of the elementary body within the host cell?

Transformation into reticulate body Signup and view all the answers

What characteristic of the elementary body contributes to its survival outside the host cell?

Cross-linking of proteins Signup and view all the answers

How do reticulate bodies reproduce within host cells?

Binary fission Signup and view all the answers

What happens approximately 35 to 40 hours post-infection of Chlamydia in host cells?

Elementary bodies are formed and released Signup and view all the answers

What structure encapsulates the reticulate bodies within host cells?

Inclusions Signup and view all the answers

What is the primary route of infection for Listeria monocytogenes?

Consumption of contaminated food Signup and view all the answers

Which of the following is a severe complication that may arise from Listeria monocytogenes infection?

Septicemia Signup and view all the answers

What characteristic allows mycoplasmas to resist certain antibiotics?

The absence of a cell wall Signup and view all the answers

Which of the following genera is known for its association with humans and significant clinical relevance?

Mycoplasma Signup and view all the answers

What type of infectious agent is Listeria monocytogenes classified as?

Facultative intracellular pathogen Signup and view all the answers

What is the generation time of Mycoplasma pneumoniae?

6 hours Signup and view all the answers

What kind of environments do mycoplasmas typically inhabit?

Close association with hosts Signup and view all the answers

What is the average size of Mycoplasma cells?

0.5 µm Signup and view all the answers

What primarily characterizes Mycoplasma and Ureaplasma cells?

Absence of a cell wall Signup and view all the answers

What is the primary mechanism by which Chlamydia trachomatis infects human cells?

Adhesion to ciliated epithelial cells using P1 adhesin protein Signup and view all the answers

Which of the following describes the reproductive strategy of obligate intracellular pathogens like Chlamydia?

They rely on host cell resources for reproduction Signup and view all the answers

Which culturing method is specifically used for obligate intracellular pathogens?

Inoculation in yolk sac of embryonated hen eggs Signup and view all the answers

What is a notable characteristic of Chlamydia species in terms of their genome size?

Their genomes are relatively small, ranging from 0.55–1 Mbp Signup and view all the answers

What is a clinical manifestation associated with Chlamydia trachomatis infection?

Neonatal conjunctivitis Signup and view all the answers

Which of the following diseases is NOT caused by Chlamydia trachomatis?

Psittacosis Signup and view all the answers

Which feature of Chlamydia makes it well suited to invade eukaryotic cells?

Well-adapted intracellular lifecycle Signup and view all the answers

Which of the following represents a method of diagnosing an infection caused by Chlamydia spp.?

PCR amplification of their DNA Signup and view all the answers

Which factor is crucial in the virulence of Chlamydia trachomatis?

P1 adhesin protein at the attachment tip Signup and view all the answers

What type of bacteria is Chlamydia trachomatis classified as?

Gram-negative obligate intracellular bacteria Signup and view all the answers

Study Notes

Taxonomy and Bacterial Diversity

Taxonomy is the classification and naming of organisms.
Classification organizes organisms into increasingly inclusive groups based on shared characteristics or evolutionary relationships.
Carl Linnaeus developed a two-part naming system (binomial nomenclature) for plants and animals in the 1700s.
This system uses a hierarchy of ranks: domain, kingdom, phylum, class, order, family, genus, and species.
Current classifications recognize three domains: Eukaryota, Bacteria, and Archaea.

Classification System

The Linnaean system, developed in the 1700s, uses a two-part name for each species (e.g., Homo sapiens).
This system creates a hierarchical ranking of organisms from genus upwards to order, class, phyla, kingdom, and domain.
Modern classification has three domains of microorganisms: Eukaryotes, Bacteria, and Archaea.

Bacterial Taxonomy

Bergey's Manual (1923) is a primary classification text for bacteria, largely based on observable characteristics (e.g., gram staining, metabolic properties).
Carl Woese's work in 1987, using 16S ribosomal RNA (rRNA) sequences, revolutionized bacterial classification, refining existing divisions and establishing new insights into evolutionary relationships.
This 16S rRNA approach remains a standard method for identifying and classifying bacteria.

Molecular Phylogeny

Systematics studies the relationships and diversity of organisms, connecting phylogeny (evolutionary relationships) to taxonomy.
Taxonomy characterizes, names, and classifies organisms, aiding in species identification and description.
Bacterial taxonomy uses a polyphasic approach combining phenotypic traits, genotypic analysis (genome sequencing), and phylogenetic analysis (evolutionary relationships).

Obtaining DNA Sequences

Isolating genomic DNA is a crucial step.
Polymerase Chain Reaction (PCR) amplifies specific DNA regions.
Small subunit ribosomal RNA (SSU rRNA) genes are highly conserved across bacteria and are readily sequenced for comparative analysis; their use aids in establishing evolutionary relationships.
Environmental samples are subjected to molecular techniques to determine evolutionary changes.
Differences in SSU rRNA sequences are measures of evolutionary divergence.

Primary and Secondary Structure of 16S rRNA

16S rRNA from Escherichia coli and Archaea show similarities in secondary structure.
Crucial differences exist in the primary (sequence) structure.
The 16S rRNA molecule is composed of conserved and variable regions.

Bacterial Diversity

Proteobacteria is the most diverse bacterial phylum, encompassing numerous species.
Proteobacteria includes more than one-third of characterized bacteria.
Many are medically, industrially, and agriculturally significant.
Horizontal gene transfer plays a significant role in shaping their metabolic diversity.
Phylogenetic overview of bacteria is available in Figure 16.1a.

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Description

Explore the fundamentals of taxonomy and bacterial diversity in this quiz. Learn about the classification systems developed by Carl Linnaeus and the hierarchical organization of organisms. Delve into the three domains of life: Eukaryota, Bacteria, and Archaea.