Podcast
Questions and Answers
What distinguishes rickettsias from most other bacteria?
What distinguishes rickettsias from most other bacteria?
- They reproduce through binary fission only.
- They can survive outside a host cell.
- They are obligate intracellular parasites. (correct)
- They are larger than most bacteria.
Which of the following diseases is caused by a rickettsial infection?
Which of the following diseases is caused by a rickettsial infection?
- Tuberculosis
- Cholera
- Typhoid fever
- Rocky Mountain spotted fever (correct)
What is a characteristic of chlamydias that differentiates them from rickettsias?
What is a characteristic of chlamydias that differentiates them from rickettsias?
- They can carry out metabolism independently.
- They are not closely related to rickettsias. (correct)
- They are transmitted by arthropods.
- They have a motile lifestyle.
What is the size range of rickettsias?
What is the size range of rickettsias?
What type of cell wall do rickettsias possess?
What type of cell wall do rickettsias possess?
Which of the following statements about rickettsias is true?
Which of the following statements about rickettsias is true?
How do chlamydias reproduce?
How do chlamydias reproduce?
Which feature is NOT associated with rickettsias?
Which feature is NOT associated with rickettsias?
What characteristic distinguishes chlamydias from mycoplasmas?
What characteristic distinguishes chlamydias from mycoplasmas?
Which of the following is true about mycoplasmas?
Which of the following is true about mycoplasmas?
What aspect of mycoplasmas helps them resist lysis?
What aspect of mycoplasmas helps them resist lysis?
Which of the following statements about Chlamydia trachomatis is correct?
Which of the following statements about Chlamydia trachomatis is correct?
What shape can mycoplasmas exhibit?
What shape can mycoplasmas exhibit?
What is a common habitat for mycoplasmas?
What is a common habitat for mycoplasmas?
How does the morphology of chlamydias compare to mycoplasmas?
How does the morphology of chlamydias compare to mycoplasmas?
Which of the following is false regarding mycoplasmas?
Which of the following is false regarding mycoplasmas?
What is the primary energy source used by photosynthetic bacteria to synthesize nutrients?
What is the primary energy source used by photosynthetic bacteria to synthesize nutrients?
Which of the following characteristics is true of cyanobacteria?
Which of the following characteristics is true of cyanobacteria?
What type of bacteria does M. hominis and Ureaplasma urealyticum belong to?
What type of bacteria does M. hominis and Ureaplasma urealyticum belong to?
What is the role of heterocysts in certain cyanobacteria?
What is the role of heterocysts in certain cyanobacteria?
What pigment gives some cyanobacteria a blue tint?
What pigment gives some cyanobacteria a blue tint?
Which feature is a specialized adaptation of cyanobacteria?
Which feature is a specialized adaptation of cyanobacteria?
Which of the following statements about bacteria is false?
Which of the following statements about bacteria is false?
How are photosynthetic bacteria different from most other bacteria?
How are photosynthetic bacteria different from most other bacteria?
What is the primary method of reproduction in cyanobacteria?
What is the primary method of reproduction in cyanobacteria?
Which of the following statements regarding cyanotoxins is accurate?
Which of the following statements regarding cyanotoxins is accurate?
How do green and purple sulphur bacteria differ from cyanobacteria?
How do green and purple sulphur bacteria differ from cyanobacteria?
In which type of environment would you most likely find green sulphur bacteria?
In which type of environment would you most likely find green sulphur bacteria?
What characteristic of purple sulphur bacteria allows them to thrive in certain conditions?
What characteristic of purple sulphur bacteria allows them to thrive in certain conditions?
What is a notable feature of certain cyanobacteria when they form water blooms?
What is a notable feature of certain cyanobacteria when they form water blooms?
What type of chlorophyll do green and purple sulphur bacteria possess?
What type of chlorophyll do green and purple sulphur bacteria possess?
Where do green and purple sulphur bacteria predominantly reside?
Where do green and purple sulphur bacteria predominantly reside?
What is the primary characteristic that allows myxobacteria to move over moist surfaces?
What is the primary characteristic that allows myxobacteria to move over moist surfaces?
Under what conditions do myxobacteria produce their fruiting bodies?
Under what conditions do myxobacteria produce their fruiting bodies?
Which of the following bacteria are known to produce myxospores?
Which of the following bacteria are known to produce myxospores?
What type of environments do appendaged bacteria typically inhabit?
What type of environments do appendaged bacteria typically inhabit?
What structure do myxobacteria produce that is similar to fungi?
What structure do myxobacteria produce that is similar to fungi?
What is a common characteristic of the life cycle in myxobacteria?
What is a common characteristic of the life cycle in myxobacteria?
How do myxobacteria adapt to their environment when food is scarce?
How do myxobacteria adapt to their environment when food is scarce?
What does the term 'appendaged bacteria' refer to?
What does the term 'appendaged bacteria' refer to?
Flashcards
Rickettsias
Rickettsias
Distinctive, tiny Gram-negative bacteria that are obligate intracellular parasites, typically transmitted between mammalian hosts via arthropod vectors.
Obligate intracellular parasites
Obligate intracellular parasites
Organisms that absolutely require a host cell for survival and reproduction, as they cannot function independently.
Rocky Mountain Spotted Fever
Rocky Mountain Spotted Fever
A human disease caused by the bacterium Rickettsia rickettsii, transmitted by ticks.
Epidemic Typhus
Epidemic Typhus
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Chlamydias
Chlamydias
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Gram-negative bacteria
Gram-negative bacteria
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Arthropod vectors
Arthropod vectors
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Binary fission
Binary fission
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Chlamydiae Obligate Parasites
Chlamydiae Obligate Parasites
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Chlamydia Reproduction
Chlamydia Reproduction
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Chlamydiae Characteristics
Chlamydiae Characteristics
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Mycoplasmas Cell Wall Lacking
Mycoplasmas Cell Wall Lacking
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Mycoplasma Stability
Mycoplasma Stability
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Mycoplasma Size & Shape
Mycoplasma Size & Shape
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Mycoplasma Growth Environment
Mycoplasma Growth Environment
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Mycoplasma Habitats
Mycoplasma Habitats
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Photosynthetic bacteria
Photosynthetic bacteria
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Cyanobacteria
Cyanobacteria
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Thylakoids
Thylakoids
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Heterocysts
Heterocysts
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Mycoplasma & Ureaplasma
Mycoplasma & Ureaplasma
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Gram-negative cell wall
Gram-negative cell wall
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Gas inclusions
Gas inclusions
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Free-living non-pathogenic bacteria
Free-living non-pathogenic bacteria
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Cyanobacteria
Cyanobacteria
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Symbiotic association
Symbiotic association
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Water blooms
Water blooms
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Cyanotoxins
Cyanotoxins
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Green and Purple Sulfur Bacteria
Green and Purple Sulfur Bacteria
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Anoxygenic photosynthesis
Anoxygenic photosynthesis
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Bacteriochlorophyll
Bacteriochlorophyll
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Anaerobic/Microaerophilic
Anaerobic/Microaerophilic
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Myxobacteria
Myxobacteria
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Fruiting bodies
Fruiting bodies
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Gliding bacteria
Gliding bacteria
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Appendaged bacteria
Appendaged bacteria
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Stalked bacteria
Stalked bacteria
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Myxospores
Myxospores
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Preferred habitats for myxobacteria
Preferred habitats for myxobacteria
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Life cycle complexity of myxobacteria
Life cycle complexity of myxobacteria
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Study Notes
Basic Microbiology Lecture - 12
- Lecture focused on prokaryotic groups with unusual characteristics, including medically significant bacteria.
Survey of Prokaryotic Groups with Unusual Characteristics
- Covered rickettsias, chlamydias, mycoplasmas, photosynthetic bacteria (including cyanobacteria), and gliding fruiting bacteria (myxobacteria).
Unusual Forms of Medically Significant Bacteria
- Rickettsias:
- Distinctive, very tiny, Gram-negative bacteria.
- Have a somewhat typical bacterial morphology, but are atypical in their life cycle and other adaptations.
- Obligate intracellular parasites, needing a host cell for survival.
- Alternate between mammalian hosts and arthropod vectors (like fleas, lice, or ticks).
- Cause diseases like Rocky Mountain spotted fever and epidemic typhus.
- Rickettsia rickettsii causes Rocky Mountain spotted fever, spread by ticks
- Rickettsia prowazekii causes epidemic typhus, spread by lice.
- Coxiella burnetti causes Q Fever, is air and dust borne by arthropods.
- Possess a gram-negative cell wall, divide by binary fission and contain DNA and RNA
- Among the smallest cells, ranging from 0.3 to 0.6μm wide and 0.8 to 2.0μm long.
- Non-motile, appearing as pleomorphic rods or coccobacilli
- Chlamydias:
- Similar to rickettsias in their requirement for host cells, but unrelated and not requiring arthropod transmission.
- Obligate intracellular parasites, depending on host cells for crucial metabolic constituents.
- Share similarities with rickettsias via size, gram-negative cell wall, and pleomorphic morphology.
- Significant dissimilarities in their life cycles exist
- Multiply by binary fission
- Chlamydia trachomatis is a significant pathogen connected to sexually transmitted, neonatal and ocular disease (trachoma), a highly common pathogen.
Mycoplasmas (Cell-Wall-Deficient Bacteria)
- Naturally lack a cell wall.
- Their cell membrane is reinforced by sterols and is resistant to lysis.
- Extremely small, pleomorphic cells, ranging in size from 0.1 to 0.5µm.
- Exhibit diverse shapes from filamentous to coccus or doughnut-shaped.
- Not obligate parasites and can be cultivated on artificial media, but sterols are necessary for cell membranes for some species.
- Occur in multiple habitats (plants, soil, animals)
- Implicated in respiratory tract illnesses by various species of Mycoplasma and in various urogenital tract infections by M. hominis and Ureaplasma urealyticum.
Free-Living Non-Pathogenic Bacteria: Photosynthetic Bacteria
- Most bacteria derive nutrients from other organisms.
- Photosynthetic bacteria employ independent cells that contain special light-trapping pigments, converting sunlight to synthesize nutrients from simple inorganic compounds
- Photosynthetic bacteria can be categorized based on oxygen production during photosynthesis.
Cyanobacteria (Blue-Green Bacteria)
- Previously called blue-green algae
- Have a gram-negative cell wall;
- Exhibit oxygenic photosynthesis.
- Contain specialized internal membranes called thylakoids—with chlorophyll pigments and photosynthetic granules.
- Range in size from 1µm to 10µm, categorized as unicellular or in colonies as filaments, sometimes with gelatinous sheaths.
- Characterized by gas inclusions, which aid in floating and increasing light exposure.
- Can form water blooms (Anabaena, Aphanizomenon, Microcystis), which can cause unpleasant odors and even livestock mortality due to toxin production and accumulation of organic matter.
- They make nitrogen fertilizer usable by plants.
- Produce cyanotoxins, which can be harmful to humans and animals (e.g., microcystin LR, nodularin R).
Green and Purple Sulphur Bacteria
- Photosynthetic bacteria that differ from cyanobacteria in their pigment type (bacteriochlorophyll) and in not producing oxygen during photosynthesis.
- Live in anaerobic habitats (sulfur springs, freshwater lakes, swamps) where light penetrates deeply enough for their pigments to absorb wavelengths, with deep anaerobic conditions.
- Occur as single cells, exhibiting varied shapes, and are usually motile.
- Utilize sulfur compounds (e.g., H₂S, S) for metabolism, sometimes storing sulfur internally as granules.
- Purple sulphur bacteria are anaerobic or microaerophilic, and green sulphur bacteria are obligate anaerobes.
Gliding Fruiting Bacteria (Myxobacteria)
- Myxobacteria, particularly the slime bacteria are interesting and highly unusual.
- Commonly found in animal dung and organic-rich soils (neutral or alkaline pH).
- Characterized by a gliding motility mechanism involving the rotation of filaments or fibers under the cell wall's outer membrane.
- Lack flagella.
- Have complex life cycles; vegetative cells form multicellular fruiting bodies, producing highly resistant myxospores.
- Fruiting body structures are often visually apparent (e.g. on tree bark and plant debris).
Appendaged Bacteria
- Bacteria such as different stalked types and different budding types have extensions from their surface, some attached tightly and some loosely (like the glycocalyx.)
- Appendages like stalks or threads can vary in type.
- Some are aquatic and can trap small organic matter.
- Budding bacteria reproduce asexually through budding from extended parts of the cell wall.
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Description
This lecture provides an overview of unusual prokaryotic groups, focusing on medically significant bacteria such as rickettsias and chlamydias. Explore the characteristics and life cycles of these unique microorganisms and their role in human diseases. Enhance your understanding of their interactions with hosts and vectors.
