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Questions and Answers
What is the primary function of a bacterial flagellum?
What is the primary function of a bacterial flagellum?
What structure is involved in the attachment of bacterial cells to surfaces or other individuals in a colony?
What structure is involved in the attachment of bacterial cells to surfaces or other individuals in a colony?
What characteristic best describes extreme thermophiles?
What characteristic best describes extreme thermophiles?
Which category of prokaryotes obtains energy from light?
Which category of prokaryotes obtains energy from light?
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Which type of bacteria includes helical heterotrophs?
Which type of bacteria includes helical heterotrophs?
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What type of nutritional mode combines energy from chemicals and carbon from CO2?
What type of nutritional mode combines energy from chemicals and carbon from CO2?
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Which structure is responsible for the transfer of genetic material between bacterial cells?
Which structure is responsible for the transfer of genetic material between bacterial cells?
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Which type of bacteria decompose soil?
Which type of bacteria decompose soil?
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What is the major difference between exotoxins and endotoxins in pathogenic bacteria?
What is the major difference between exotoxins and endotoxins in pathogenic bacteria?
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What do heterotrophs require as a carbon source?
What do heterotrophs require as a carbon source?
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What adaptation allows some pathogenic bacteria to cause disease even if the bacteria are no longer present?
What adaptation allows some pathogenic bacteria to cause disease even if the bacteria are no longer present?
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Which bacteria is known to break down food undigested by human intestines?
Which bacteria is known to break down food undigested by human intestines?
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Which type of prokaryote generates oxygen?
Which type of prokaryote generates oxygen?
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What is a distinguishing feature of bacteriophages?
What is a distinguishing feature of bacteriophages?
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What determines whether a virus is categorized as a DNA virus or an RNA virus?
What determines whether a virus is categorized as a DNA virus or an RNA virus?
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Which of the following structures is responsible for enclosing the viral genome?
Which of the following structures is responsible for enclosing the viral genome?
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What are capsomeres?
What are capsomeres?
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What is a distinctive feature of methanogens?
What is a distinctive feature of methanogens?
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From where do viral envelopes originate?
From where do viral envelopes originate?
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How do bacteriophages typically insert their DNA into a host?
How do bacteriophages typically insert their DNA into a host?
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What is the function of a viral envelope?
What is the function of a viral envelope?
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Which of the following molecules can be found in viral envelopes?
Which of the following molecules can be found in viral envelopes?
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Study Notes
Cell-Surface Structures
- Bacterial cell walls have various structures involved in locomotion, attachment, and genetic material transfer.
- Flagella are responsible for locomotion of the cell.
- Fimbriae are involved in attachment to suitable surfaces or other individuals in a colony.
- Sex pili are responsible for transferring genetic material.
Prokaryote Nutritional and Metabolic Adaptations
- 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 as a carbon source.
- Four major modes of nutrition are:
- Photoautotrophy
- Chemoautotrophy
- Photoheterotrophy
- Chemoheterotrophy
Archaea
- Archaea share certain traits with bacteria and other traits with eukaryotes.
- Some archaea are extremophiles, living in extreme environments.
- Examples of extremophiles include:
- Extreme halophiles (living in highly saline environments)
- Extreme thermophiles (thriving in very hot environments)
- Methanogens (strict anaerobes that produce methane as a waste product)
Bacteria
- Bacteria include the vast majority of prokaryotes.
- Proteobacteria are gram-negative bacteria that include photoautotrophs, chemoautotrophs, and heterotrophs.
- Some proteobacteria are anaerobic, while others are aerobic.
- Cyanobacteria are photoautotrophs that generate O2.
- Chlamydias are parasitic bacteria that live within animal cells.
- Spirochetes are helical heterotrophs.
- Gram-positive bacteria include:
- Actinomycetes (decomposing soil)
- Some Staphylococcus and Streptococcus (pathogenic)
- Mycoplasms (the smallest known cells)
Prokaryote Impact on Humans
- Prokaryotes have both beneficial and harmful impacts on humans.
- Some prokaryotes are human pathogens, while others have positive interactions with humans.
- Mutualistic bacteria:
- Live in human intestines (about 500-1,000 species)
- Break down undigested food
- Pathogenic bacteria:
- Cause about half of all human diseases
- Examples include Lyme disease
- Pathogenic prokaryotes typically cause disease by releasing exotoxins or endotoxins.
- Exotoxins are secreted and cause disease even if the prokaryotes are not present.
- Endotoxins are released when bacteria die and their cell walls break down.
Structure of Viruses
- Viral genomes are classified as DNA or RNA viruses based on the type of nucleic acid.
- Viral genomes may consist of:
- Double- or single-stranded DNA
- Double- or single-stranded RNA
- Capsids are protein shells that enclose the viral genome.
- Capsids can have various structures depending on the type of virus.
- Capsids are built from protein subunits called capsomeres.
- Many complex capsids are found among bacteriophages.
- Phages are viruses that infect bacteria and have elongated capsid heads that enclose their DNA.
- A protein tail piece attaches the phage to the host and injects the phage DNA inside.
- Some viruses have membranous envelopes that help them infect hosts.
- Viral envelopes contain a combination of viral and host cell molecules.
- Examples of viruses with membranous envelopes include influenza viruses.
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Description
This quiz covers the various structures found on the outer surface of the bacterial cell wall, including their functions and characteristics.
