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Questions and Answers
What is the size range of bacteria and archaea?
What is the size range of bacteria and archaea?
Which of the following structures in bacteria is responsible for adjusting buoyancy?
Which of the following structures in bacteria is responsible for adjusting buoyancy?
Which pigment is primarily involved in the process of photosynthesis in bacteria?
Which pigment is primarily involved in the process of photosynthesis in bacteria?
What shape is characterized by bacilli bacteria?
What shape is characterized by bacilli bacteria?
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How do magnetosomes assist bacteria?
How do magnetosomes assist bacteria?
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What is the primary function of mucilage secreted by microorganisms?
What is the primary function of mucilage secreted by microorganisms?
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What distinguishes Gram-positive bacteria from Gram-negative bacteria?
What distinguishes Gram-positive bacteria from Gram-negative bacteria?
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Which of the following shapes corresponds to Lactobacillus plantarum?
Which of the following shapes corresponds to Lactobacillus plantarum?
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Why are Gram-positive bacteria more vulnerable to penicillin?
Why are Gram-positive bacteria more vulnerable to penicillin?
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What role do biofilms play in the survival of microorganisms?
What role do biofilms play in the survival of microorganisms?
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How do Gram-negative bacteria typically resist antibiotics?
How do Gram-negative bacteria typically resist antibiotics?
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Which characteristic is common to most bacteria’s cell walls?
Which characteristic is common to most bacteria’s cell walls?
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What is the significance of the Gram staining process?
What is the significance of the Gram staining process?
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Which type of bacteria primarily synthesizes its own organic compounds using light as an energy source?
Which type of bacteria primarily synthesizes its own organic compounds using light as an energy source?
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What term describes a symbiotic relationship where one organism benefits at the expense of the other?
What term describes a symbiotic relationship where one organism benefits at the expense of the other?
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Which group of organisms is involved in nitrogen fixation and converts nitrogen gas (N2) into usable compounds for plants?
Which group of organisms is involved in nitrogen fixation and converts nitrogen gas (N2) into usable compounds for plants?
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How do heterotrophs obtain organic carbon for growth?
How do heterotrophs obtain organic carbon for growth?
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Which of the following refers to a close association between an organism and another organism without harming each other?
Which of the following refers to a close association between an organism and another organism without harming each other?
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What is the primary function of cyanobacteria in mutualistic relationships with fungi?
What is the primary function of cyanobacteria in mutualistic relationships with fungi?
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In terms of classification and nutrition, which bacteria use chemical modification of inorganic compounds to synthesize organic compounds?
In terms of classification and nutrition, which bacteria use chemical modification of inorganic compounds to synthesize organic compounds?
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What is the size of a typical heterocyte?
What is the size of a typical heterocyte?
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What characterizes viruses in terms of basic biological functions?
What characterizes viruses in terms of basic biological functions?
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Which step is NOT part of the viral reproductive cycle?
Which step is NOT part of the viral reproductive cycle?
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What distinguishes prions from viruses?
What distinguishes prions from viruses?
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How do Gram-negative pathogenic bacteria interact with host cells?
How do Gram-negative pathogenic bacteria interact with host cells?
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What is a characteristic of both viruses and viroids?
What is a characteristic of both viruses and viroids?
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What is true about the structure of viruses?
What is true about the structure of viruses?
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The abnormal form of protein in prions is referred to as which of the following?
The abnormal form of protein in prions is referred to as which of the following?
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Which one of the following statements is true regarding the behavior of viruses?
Which one of the following statements is true regarding the behavior of viruses?
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What is the primary function of resistance plasmids (R factors)?
What is the primary function of resistance plasmids (R factors)?
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Which type of plasmid allows for the mating process in bacteria?
Which type of plasmid allows for the mating process in bacteria?
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What natural process involves a virus transferring genetic information between bacteria?
What natural process involves a virus transferring genetic information between bacteria?
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What do endospores provide to certain bacteria?
What do endospores provide to certain bacteria?
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What type of plasmid encodes proteins that kill other bacteria?
What type of plasmid encodes proteins that kill other bacteria?
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Which statement about transformation is true?
Which statement about transformation is true?
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What is the role of heterocytes found in cyanobacteria?
What is the role of heterocytes found in cyanobacteria?
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How do plasmids generally compare to bacterial chromosomes?
How do plasmids generally compare to bacterial chromosomes?
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Study Notes
Bacteria and Archaea
- Bacteria and archaea share small size, rapid growth, and simple cellular structure.
- Most bacteria and archaea are 1–5 μm in diameter, while most plant and animal cells are 10–100 μm in diameter.
- Small cell size limits the amount of materials but allows faster cell division.
Bacterial Structure and Movement
- Thylakoids: ingrowths of plasma membrane that increase surface area for photosynthesis.
- Chlorophyll: pigment that absorbs light energy in photosynthesis.
- Gas vesicle: adjusts buoyancy
- Nucleus-like bodies: from plasma membrane invaginations
- Magnetosomes: magnetite crystals that act like a compass and help locate low-oxygen habitats.
- Five major shapes: spheres (cocci), rods (bacilli), comma-shaped (vibrios), spiral-shaped flexible (spirochaetes) and spiral-shaped rigid (spirilli).
- Bacteria occur as single cells, pairs, or filaments.
- Mucilage: a thick substance consisting of sugars, proteins, fats, and nucleic acids that is secreted from cells.
- Mucilage functions: movement, evade host defenses and hold colonies together as biofilms.
Bacterial Cell Walls
- Most bacteria have a rigid cell wall outside the plasma membrane.
- The cell wall maintains cell shape and helps protect against attack.
- The cell wall also helps avoid lysis in hypotonic solutions.
- Most bacteria use peptidoglycan as an important component of cell walls.
Gram Staining
- Gram-positive: have a relatively thick peptidoglycan layer, retain purple dye and are vulnerable to penicillin.
- Gram-negative: have less peptidoglycan, a thin outer envelope of lipopolysaccharides, retain a pink stain and resist penicillin.
Bacterial Reproduction
- Bacterial chromosomes: molecules of double-stranded DNA, usually circular.
- Plasmids: small, circular pieces of DNA that exist independently of the bacterial chromosome and have their own origin of replication.
- Five types of plasmids: resistance plasmids (R factors), degradative plasmids, col-plasmids, virulence plasmids, and fertility plasmids (F factors).
- Genetic diversity: arises from mutations, conjugation, transformation and transduction.
- Conjugation: direct physical interaction for genetic transfer from donor to recipient cell.
- Transformation: DNA released from a dead bacterium is taken up by another bacteria.
- Transduction: a virus transfers genetic information from one bacterium to another.
- Akinetes: found in aquatic filamentous cyanobacteria, develop in winter and produce new filaments in spring.
- Heterocyte: specialized cell that converts atmospheric nitrogen into forms utilizable by photosynthetic organisms.
- Endospores: tough protein coat with a long dormant span, found in some Gram-positive bacteria.
Bacterial Nutrition and Metabolism
- Autotrophs: produce all or most of their own organic compounds.
- Photoautotrophs: use light as an energy source for the synthesis of organic compounds.
- Chemoautotrophs: use energy obtained from the chemical modification of inorganic compounds to synthesize organic compounds.
- Heterotrophs: uses organic carbon for growth by consuming other organisms.
Ecological Roles and Biotechnology Applications of Bacteria
- Symbiosis: an organism that lives in close association with one or more other organisms.
- Parasitism: one partner benefits at the expense of the other.
- Mutualism: an association beneficial to both partners.
- Diazotrophs: conduct nitrogen fixation, converting inorganic nitrogen gas N2 into N compounds.
- Rhizobium: forms mutualism with legumes.
- Lichens: mutualism between cyanobacteria and fungi.
- Microbiome: microbes that live in or on living organisms.
- Gram-negative pathogenic bacteria: have developed channels to inject DNA into animal and plant cells.
Viruses and Prions
- Viruses consist of nucleic acid enclosed in a protein coat, require living cells to reproduce and vary greatly in their characteristics.
- Viral structure: includes a capsid (protein coat) and a genome (DNA or RNA).
- Viral reproductive cycle: attachment, entry, integration, synthesis of viral components, viral assembly, release.
- Prions: infectious proteins that convert normal proteins to abnormal forms.
- Prion diseases: neurodegenerative diseases in humans and livestock.
- Normal conformation: PrP C
- Disease-causing conformation: PrP Sc
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Description
This quiz explores the fundamental characteristics and structures of bacteria and archaea, including their sizes, shapes, and cellular components. It also covers aspects of bacterial movement and unique structures such as thylakoids and magnetosomes. Test your understanding of these essential microorganisms.
