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Questions and Answers
What is the size range of bacteria?
Which type of bacteria are non-motile and generally spherical in shape?
What is the characteristic shape of vibriones?
Which group of bacteria can form chains?
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What type of bacteria are known to move by flagella?
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Which adaptation allows certain bacteria to thrive in extreme conditions?
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What feature distinguishes spirochaetes from other spiral-shaped bacteria?
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What is a characteristic of swimming bacteria?
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What is the defining characteristic of lophotrichous bacteria?
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What do photoautotrophic bacteria use as their source of hydrogen?
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Which type of bacteria is known for using the oxidation of ammonia to derive energy?
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Which structure is not a part of the bacterial cell?
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Which of the following correctly describes heterotrophic bacteria?
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What distinguishes anoxygenic photosynthesis from oxygenic photosynthesis?
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What type of bacteria utilize energy from the oxidation of inorganic substances?
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Which of the following bacteria is specifically known for oxidizing hydrogen sulfide to derive energy?
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What is the role of nitrogen-fixing bacteria in leguminous plants?
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What type of bacteria obtain nutrients from living hosts and can cause disease?
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Which of the following describes binary fission?
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Which of the following reproductive methods allows bacteria to survive unfavorable conditions?
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What are endospores capable of withstanding?
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Which form of bacterial reproduction is not common and involves the transfer of nuclear material?
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What type of bacteria feed on dead organic matter?
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How long does binary fission take to occur?
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Study Notes
Bacteria
- Prokaryotic microorganisms
- Range in size from 1 to 15 microns
- Most abundant organisms on Earth
- Can live in diverse conditions:
- Cold and hot regions
- High mountains
- High salt concentration
- Dry places
- Stomach juice (acidic with enzymes)
- Vinegar
- Absence of oxygen
- Boiling water
Bacterial Morphology
- Four main shapes:
- Spherical (Cocci)
- Micrococci: Single cells
- Diplococci: Occur in pairs after dividing in one plane
- Rod-shaped (Bacilli)
- Small short or long cylinders with tapered or curved ends
- Single bacilli: Occur singly
- Diplobacilli: Occur in pairs
- Streptobacilli: Occur in a chain
- Spiral-shaped
- Vibriones: Comma-shaped, rigid cell wall, move by flagella
- Spirilla: Less-twisted, rigid cell wall, move by flagella
- Spirochaetes: Much-twisted, non-rigid cell wall, worm-like movement
- Filamentous (Actinomycetes)
- Branched filaments similar to fungi
- Spherical (Cocci)
Motility of Bacteria
- Either motile or non-motile
- Most cocci are non-motile
- Transfer from place to place through the movement of their environment (air, water, soil)
- Most bacilli and spiral-shaped bacteria are motile
- Motile bacteria can creep or swim
- Creeping bacteria: No organs of movement, slow movement by contractions
- Swimming bacteria: Move freely in liquid, flagella as organ of movement
Flagella and Motility
- Different types of flagella based on their number and position:
- Monotrichous: One flagellum at one end
- Lophotrichous: Many flagella at one end
- Amphitrichous: One or more flagella at both ends
- Peritrichous: Many flagella surrounding the cell
Bacterial Cell Structure
- Composed of:
- Capsule
- Cell wall
- Cytoplasmic membrane
- Cytoplasm
- Flagellum
- Fimbriae
- Nuclear material
Autotrophic Bacteria
- Can synthesize their own organic food from inorganic substances
- Use carbon dioxide for carbon and hydrogen sulfide (H2S), ammonia (NH3), or hydrogen (H2) for hydrogen
- Two types:
-
Photoautotrophic Bacteria:
- Possess photosynthetic pigments in lamellae (thylakoids)
- Utilize solar energy
- Bacterial photosynthesis differs from plant photosynthesis:
- Water is not used as a hydrogen donor
- Oxygen is not a by-product
- This process is called anoxygenic photosynthesis
-
Chemosynthetic Bacteria:
- Manufacture organic compounds from inorganic raw materials using energy from the oxidation of inorganic substances
- Types:
- Nitrifying bacteria: Oxidize ammonia to nitrates (e.g. Nitrosomonas, Nitrobacter)
- Sulphur bacteria: Oxidize hydrogen sulfide to sulfur (e.g. Thiobacillus, Beggiatoa)
- Iron bacteria: Oxidize ferrous ions to ferric form (e.g. Ferrobacillus, Gallionella).
-
Photoautotrophic Bacteria:
Heterotrophic Bacteria
- Cannot synthesize their own food, reliant on organic sources
- Three types:
- Symbiotic Bacteria: Mutually beneficial association with other organisms - Derive nutrients from their host but provide benefits - E.g. nitrogen-fixing bacteria in the root nodules of legumes (Rhizobium, Pseudomonas)
- Parasitic Bacteria: Live in the body of animals or plants, obtaining food from their host - Often pathogenic, causing disease by exploiting the host or releasing toxins
- Saprophytic bacteria: Decompose dead organic matter
Reproduction of Bacteria
- Three types:
-
Vegetative Reproduction:
- By binary fission (rapid and simple division)
- Takes 30 minutes to 6 hours
-
Asexual Reproduction:
- Occurs in unfavorable conditions
- Two forms:
- Conidia formation: Separation of the end of filaments, formation of a chain of conidia that can resist dryness
- Endospores: Resist high temperature, acidity, and alkalinity
-
Sexual Reproduction:
- Not common
- Called conjugation
- Transfer of genetic material from one cell to another, forming two mutant cells.
-
Vegetative Reproduction:
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Description
This quiz explores the fascinating world of bacteria, including their characteristics, ecological diversity, and morphological forms. Learn about the different shapes of bacteria such as cocci, bacilli, and spirilla, as well as their unique adaptations to survive in varied environments.
