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What is the significance of Cyanobacteria in ecosystems?
What is the significance of Cyanobacteria in ecosystems?
Which of the following bacteria is NOT a pathogenic species?
Which of the following bacteria is NOT a pathogenic species?
What is unique about the habitat of Extreme Halophiles?
What is unique about the habitat of Extreme Halophiles?
What is the primary function of Chemoheterotrophic prokaryotes in ecosystems?
What is the primary function of Chemoheterotrophic prokaryotes in ecosystems?
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Which of the following is an example of a symbiotic relationship?
Which of the following is an example of a symbiotic relationship?
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What is the characteristic of Proteobacteria that allows them to thrive in a variety of environments?
What is the characteristic of Proteobacteria that allows them to thrive in a variety of environments?
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What is the byproduct of Methanogens' metabolic activities?
What is the byproduct of Methanogens' metabolic activities?
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Which of the following extremophiles thrive in very hot environments?
Which of the following extremophiles thrive in very hot environments?
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What is the primary function of fimbriae in prokaryotes?
What is the primary function of fimbriae in prokaryotes?
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What is the term for the movement of bacteria towards or away from a chemical stimulus?
What is the term for the movement of bacteria towards or away from a chemical stimulus?
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What is the composition of bacterial flagella?
What is the composition of bacterial flagella?
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What is the region of the prokaryotic cell where the genome is located?
What is the region of the prokaryotic cell where the genome is located?
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What is the term for the process by which bacteria reproduce?
What is the term for the process by which bacteria reproduce?
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What is the primary factor contributing to genetic diversity in bacteria?
What is the primary factor contributing to genetic diversity in bacteria?
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What is the process called when a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment?
What is the process called when a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment?
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What is the term for the metabolically inactive structures formed by some bacteria to survive harsh conditions?
What is the term for the metabolically inactive structures formed by some bacteria to survive harsh conditions?
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Which of the following is an example of a symbiotic relationship involving prokaryotes?
Which of the following is an example of a symbiotic relationship involving prokaryotes?
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What is the purpose of pili (or sex pili) in prokaryotes?
What is the purpose of pili (or sex pili) in prokaryotes?
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Which of the following is a characteristic of obligate anaerobes?
Which of the following is a characteristic of obligate anaerobes?
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Which of the following prokaryotes is an example of an extremophile?
Which of the following prokaryotes is an example of an extremophile?
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What is the term for the process by which some prokaryotes convert atmospheric nitrogen to ammonia?
What is the term for the process by which some prokaryotes convert atmospheric nitrogen to ammonia?
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Which of the following is a characteristic of facultative anaerobes?
Which of the following is a characteristic of facultative anaerobes?
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Which of the following prokaryotes is an example of a pathogenic bacterium?
Which of the following prokaryotes is an example of a pathogenic bacterium?
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Which of the following is NOT a mode of nutrition in prokaryotes?
Which of the following is NOT a mode of nutrition in prokaryotes?
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What is the surprising feature of the phylogenetic tree regarding Eukarya and Archaea?
What is the surprising feature of the phylogenetic tree regarding Eukarya and Archaea?
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Which group of Archaea is found in a broad range of environments?
Which group of Archaea is found in a broad range of environments?
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Which domain of life includes organisms that are widely diverse and found in many environments?
Which domain of life includes organisms that are widely diverse and found in many environments?
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Which type of Proteobacteria is associated with stomach ulcers?
Which type of Proteobacteria is associated with stomach ulcers?
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What is a common feature of extremophiles?
What is a common feature of extremophiles?
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What is a characteristic of Gram-positive bacteria?
What is a characteristic of Gram-positive bacteria?
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What is a characteristic of Chlamydia?
What is a characteristic of Chlamydia?
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Which group of Bacteria includes Rhizobium, which forms nodules in plant roots?
Which group of Bacteria includes Rhizobium, which forms nodules in plant roots?
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Study Notes
Genetic Recombination
- A prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment in a process called transformation.
- Transduction is the movement of genes between bacteria by bacteriophages (viruses that infect bacteria).
- Conjugation is the process where genetic material is transferred between prokaryotic cells.
- In bacteria, the DNA transfer is one way, from a donor cell to a recipient cell.
- A donor cell attaches to a recipient by a pilus, pulls it closer, and transfers DNA.
- A piece of DNA called the F factor is required for the production of pili.
Metabolism and Nutrition
- Prokaryotes can be categorized by how they obtain energy and carbon.
- Phototrophs obtain energy from light.
- Chemotrophs obtain energy from chemicals.
- Autotrophs require CO2 as a carbon source.
- Heterotrophs require an organic nutrient to make organic compounds.
- Nitrogen is essential for the production of amino acids and nucleic acids.
- In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3).
- In the cyanobacterium Anabaena, photosynthetic cells and nitrogen-fixing cells called heterocysts exchange metabolic products.
Prokaryotic Metabolism
- Prokaryotic metabolism varies with respect to O2.
- Obligate aerobes require O2 for cellular respiration.
- Obligate anaerobes are poisoned by O2 and use fermentation or anaerobic respiration.
- Facultative anaerobes can survive with or without O2.
Prokaryotic Diversity
- Domain Archaea shares certain traits with bacteria and other traits with eukaryotes.
- Some archaea live in extreme environments and are called extremophiles.
- Extreme halophiles (Clade Euryarchaeota) live in highly saline environments.
- Extreme thermophiles (Clade Crenarchaeota) thrive in very hot environments.
- Methanogens (Clade Euryarchaeota) live in swamps and marshes and produce methane as a waste product.
- Methanogens are strict anaerobes and are poisoned by O2.
Domain Bacteria
- Proteobacteria are gram-negative bacteria that include photoautotrophs, chemoautotrophs, and heterotrophs.
- Some are anaerobic, and others aerobic.
- Chlamydia are parasites that live only within animal cells.
- Cyanobacteria are photoautotrophs that generate O2.
- Gram-positive bacteria include Actinomycetes, which decompose organic matter, and Bacillus anthracis, the cause of anthrax.
Ecological Importance
- Prokaryotes play a major role in the recycling of chemical elements between the living and nonliving components of ecosystems.
- Chemoheterotrophic prokaryotes function as decomposers, breaking down dead organisms and waste products.
- Prokaryotes can increase the availability of nitrogen, phosphorus, and potassium for plant growth.
- Symbiosis is an ecological relationship in which two species live in close contact: a larger host and smaller symbiont.
- Some prokaryotes have fimbriae, which allow them to stick to their substrate or other individuals in a colony.
Locomotion
- Many bacteria exhibit taxis, the ability to move toward or away from a stimulus.
- Chemotaxis is the movement toward or away from a chemical stimulus.
- Most motile bacteria propel themselves by flagella scattered about the surface or concentrated at one or both ends.
- Bacterial flagella are composed of a motor, hook, and filament.
Internal Organization
- Prokaryotic cells usually lack complex compartmentalization.
- Some prokaryotes do have in-foldings of the plasma membrane that perform metabolic functions.
- Most of the genome consists of a circular chromosome located in the nucleoid region.
- Some species of bacteria also have smaller rings of DNA called plasmids.
Prokaryotic Reproduction
- Bacteria are small, reproduce by binary fission (1-3 hours), and have short generation times.
- Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries.
- Rapid reproduction, mutation, and genetic recombination contribute to genetic diversity in bacteria.
- Mutation rates during binary fission are low, but rapid reproduction allows for rapid evolution.
Domain Diversity
- The three main domains of life are Eukarya, Archaea, and Bacteria
- Eukarya and Archaea are sister taxa, despite being eukaryotic and prokaryotic respectively
Archaea
- Archaea are extremophiles, living in extreme environments
- Examples of extreme environments include salt-loving (halophiles) and heat-loving (thermophiles)
- There are five groups of Archaea:
- URI Archaea, found in a broad range of environments
- Thermophiles, found in hot springs
- Methanogens, generating methane as a byproduct of metabolism
- Others
Domain Bacteria
- Bacteria are a widely diverse group of organisms found in many environments
- While some bacteria perform beneficial functions, others are responsible for diseases
- Subdivisions of bacteria include:
- Proteobacteria, which are gram-negative
- Chlamydia, which are gram-negative and mostly parasitic
- Spirochetes, which are gram-negative and have a helical shape
- Cyanobacteria, which are gram-positive and photosynthetic
- Gram-positive bacteria, including Bacillus, Clostridium, and Staphylococcus
Proteobacteria
- Examples of Proteobacteria include:
- Alpha Proteobacteria, such as Rhizobium, which forms nodules in plant roots
- Gamma Proteobacteria, such as Pseudomonas fluorescens, which is a nitrogen-fixing bacteria
- Delta Proteobacteria, such as Myxobacteria, which attack other bacteria and take their resources
- Epsilon Proteobacteria, such as Helicobacter pylori, which is associated with stomach ulcers
Chlamydia
- Examples of Chlamydia include:
- Chlamydia trachomatis, which is responsible for non-gonococcal urethritis (a sexually transmitted disease)
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Description
This quiz covers the different ways genetic material is transferred between prokaryotic cells, including transformation, transduction, conjugation, and horizontal gene transfer.
