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Questions and Answers
Rules for naming bacteria are the same as those used to name other organisms.
Rules for naming bacteria are the same as those used to name other organisms.
False (B)
Bacteria have been found in fossils.
Bacteria have been found in fossils.
True (A)
All prokaryotes reproduce asexually.
All prokaryotes reproduce asexually.
True (A)
Some bacteria in Domain Archaea are known to cause disease in animals.
Some bacteria in Domain Archaea are known to cause disease in animals.
Bacteria in Phylum Proteobacteria are all Gram-negative.
Bacteria in Phylum Proteobacteria are all Gram-negative.
According to the second edition of Bergey's Manual, how many prokaryotic phyla are recognized?
According to the second edition of Bergey's Manual, how many prokaryotic phyla are recognized?
Of the following listed events, which is the correct sequence that led to the modern-day classification system for prokaryotic organisms?
Of the following listed events, which is the correct sequence that led to the modern-day classification system for prokaryotic organisms?
Which of the following is the best definition for a bacterial species?
Which of the following is the best definition for a bacterial species?
What field of microbiology is the driving force behind identification of bacterial species?
What field of microbiology is the driving force behind identification of bacterial species?
Approximately how many bacterial species have been identified as pathogenic in humans?
Approximately how many bacterial species have been identified as pathogenic in humans?
All of the following are classification tools for bacteria EXCEPT:
All of the following are classification tools for bacteria EXCEPT:
Which would be the most ideal colony count for calculating total CFU/ml in a culture sample that has been serially diluted?
Which would be the most ideal colony count for calculating total CFU/ml in a culture sample that has been serially diluted?
Which is NOT true about the pour plate method for culturing bacterial colonies?
Which is NOT true about the pour plate method for culturing bacterial colonies?
Which was NOT one of the most common issues that could have potentially led to inaccurate results when using (Eppendorf) micropipettes in our lab?
Which was NOT one of the most common issues that could have potentially led to inaccurate results when using (Eppendorf) micropipettes in our lab?
What is the primary evidence used to separate the two phyla of Domain Archaea?
What is the primary evidence used to separate the two phyla of Domain Archaea?
Why are thermophiles and hyperthermophiles able to withstand such high environmental temperatures?
Why are thermophiles and hyperthermophiles able to withstand such high environmental temperatures?
Methanogens are all what type of respiration?
Methanogens are all what type of respiration?
Which phyla of bacteria are thought to have transformed the atmosphere of early earth from anaerobic to one that contains oxygen?
Which phyla of bacteria are thought to have transformed the atmosphere of early earth from anaerobic to one that contains oxygen?
Which bacterial genus has been shown to benefit individuals when ingested and is currently marketed as a probiotic for humans?
Which bacterial genus has been shown to benefit individuals when ingested and is currently marketed as a probiotic for humans?
Which phylum of bacteria contains a high G+C ratio?
Which phylum of bacteria contains a high G+C ratio?
What structures do cyanobacteria form in order to avoid the conflict between nitrogen-fixing enzymes and oxygen?
What structures do cyanobacteria form in order to avoid the conflict between nitrogen-fixing enzymes and oxygen?
Endospores do what three things?
Endospores do what three things?
Which best describes stiff, spiral-shaped prokaryotic cells?
Which best describes stiff, spiral-shaped prokaryotic cells?
The type of reproduction that results in a palisade arrangement of cells is called?
The type of reproduction that results in a palisade arrangement of cells is called?
Which of the following genera of bacteria lack a cell wall?
Which of the following genera of bacteria lack a cell wall?
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Study Notes
Prokaryotic Classification and Characteristics
- Naming rules for bacteria differ from those for other organisms.
- Fossils reveal the historical presence of bacteria.
- Prokaryotes exclusively reproduce asexually.
- Archaea contains no known pathogenic bacteria affecting animals.
- Phylum Proteobacteria is characterized by all members being Gram-negative.
Classification of Prokaryotes
- Bergey’s Manual recognizes a total of 25 prokaryotic phyla.
- Sequence for modern classification: introduction of "prokaryote," establishment of the five-kingdom system, followed by the three-domain system.
- A bacterial species is defined as a population of cells sharing similar characteristics.
- Medical microbiology is crucial for identifying bacterial species.
Pathogenic Bacteria and Classification Tools
- Fewer than 10% of identified bacterial species are pathogenic to humans.
- Common classification tools include dichotomous keys, phylogenetic trees, and cladograms; advanced fluorescence typing is not commonly used.
Laboratory Techniques and Methodologies
- An ideal colony count for calculating total CFU/ml in diluted samples is approximately 180.
- The pour plate method may provide lower colony counts compared to the streak plate method and allows for growth on the surface and within agar; however, autoclaving during certain stages is not required.
- Key errors while using micropipettes include not recognizing stops correctly and pressing the trigger too quickly; using the wrong pipette tip is not a common issue.
Domain Archaea and Bacterial Phyla
- rRNA sequences serve as primary evidence to differentiate Archaea phyla.
- Thermophiles and hyperthermophiles survive high temperatures due to biochemical adaptations.
- Methanogens are categorized as obligate anaerobes.
Environmental Impact and Beneficial Prokaryotes
- Cyanobacteria contributed to transforming Earth’s atmosphere from anaerobic to aerobic by increasing oxygen levels.
- Lactobacillus is a bacterial genus marketed as a probiotic, offering health benefits when ingested.
- Actinobacteria is noted for high G+C ratios within its genetic material.
Unique Adaptations in Bacteria
- Cyanobacteria form heterocysts to separate nitrogen-fixing enzymes from oxygen production.
- Endospores enable bacteria to remain dormant, survive for decades, and endure extreme conditions like boiling water.
- Spirilla are identified as stiff, spiral-shaped prokaryotic cells.
- Snapping division reproduction results in palisade arrangements of cells.
Cell Wall Characteristics
- Mycoplasma is a notable genus of bacteria that lacks a cell wall, differing from Mycobacterium, Bacteroides, and Actinomyces.
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