Prokaryotes: Archaea & Eubacteria Overview
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Questions and Answers

Which statement about the cell membrane and wall of Archaea is correct?

  • They lack any form of protective structural components.
  • They possess a unique lipid layer structure. (correct)
  • They contain high levels of peptidoglycan.
  • They are structurally identical to those in eubacteria.

What is a key characteristic of methanogens?

  • They generate energy by converting chemical compounds into methane. (correct)
  • They thrive in aerobic conditions.
  • They decompose methane in high oxygen environments.
  • They produce oxygen as a byproduct.

Which of the following organisms would be classified as an extreme thermophile?

  • An organism that can grow at temperatures of 70°C to 95°C. (correct)
  • An organism thriving at temperatures above 100°C.
  • An organism living in highly saline waters.
  • An organism found in the Arctic oceans.

Which environment is least likely to support halophiles?

<p>A freshwater lake. (B)</p> Signup and view all the answers

What is the optimal growth temperature range for psychrophiles?

<p>-10°C to -20°C. (C)</p> Signup and view all the answers

What is a potential outcome of bacteria swapping and gaining new DNA?

<p>Development of pathogenic traits (A)</p> Signup and view all the answers

How does the use of antibiotics on a bacterial population affect its overall strength?

<p>It culls the weaker bacteria, leaving more resistant ones to thrive (A)</p> Signup and view all the answers

What is the consequence of a patient ceasing antibiotic treatment early?

<p>A mixed population of sensitive and resistant bacteria is maintained (C)</p> Signup and view all the answers

Which of the following statements about the characteristics of bacteria and mutations is false?

<p>All mutations lead to beneficial outcomes for bacteria (D)</p> Signup and view all the answers

Why are antibiotics ineffective against viral infections?

<p>Antibiotics do not target viral structures (C)</p> Signup and view all the answers

What is the primary role of decomposers in an ecosystem?

<p>They break down dead or decaying organisms. (A)</p> Signup and view all the answers

Which reproductive process allows for the exchange of genetic information between two bacterial cells?

<p>Conjugation (A)</p> Signup and view all the answers

What characteristic of endospores enables bacteria to survive in extreme environments?

<p>They form a protective encasement around the chromosome. (B)</p> Signup and view all the answers

Which type of symbiotic relationship is characterized by one organism benefiting while the other is not affected?

<p>Commensalism (D)</p> Signup and view all the answers

What is the significance of mutations in bacterial populations?

<p>They provide genetic diversity. (B)</p> Signup and view all the answers

What is the main component that makes up the bacterial cell wall?

<p>Peptidoglycan (B)</p> Signup and view all the answers

Which classification of bacteria cannot survive in the presence of oxygen?

<p>Obligate anaerobes (C)</p> Signup and view all the answers

How are ribosomes involved in cellular function?

<p>They translate DNA information to make proteins. (D)</p> Signup and view all the answers

What type of bacteria can utilize both aerobic respiration and anaerobic fermentation depending on oxygen availability?

<p>Facultative aerobes (A)</p> Signup and view all the answers

What is the function of plasmids in bacteria?

<p>They carry genes that can confer antibiotic resistance. (D)</p> Signup and view all the answers

Which of the following statements about bacterial metabolism is true?

<p>Some bacteria can produce their own food from inorganic substances. (C)</p> Signup and view all the answers

Which shape is not associated with bacterial classification?

<p>Hexagon (C)</p> Signup and view all the answers

What characteristic is common among bacteria that are classified as saprotrophs?

<p>They obtain carbon from dead organic matter. (B)</p> Signup and view all the answers

What characteristic primarily distinguishes Gram-positive bacteria from Gram-negative bacteria?

<p>Amount of peptidoglycan in the cell wall (D)</p> Signup and view all the answers

Which of the following groups contains ancestors of chloroplasts?

<p>Cyanobacteria (D)</p> Signup and view all the answers

What is the role of the slime layer or capsule found in some bacteria?

<p>To camouflage the cell from immune responses (C)</p> Signup and view all the answers

Which type of bacteria is typically more resistant to antibiotics?

<p>Gram-negative bacteria (C)</p> Signup and view all the answers

Which of the following bacteria is known for causing diseases such as gonorrhea and dysentery?

<p>Proteobacteria (D)</p> Signup and view all the answers

What is the general effect of the peptidoglycan layer on Gram-positive bacteria regarding their interaction with the human body?

<p>They are attacked by enzymes produced by the human body. (A)</p> Signup and view all the answers

Which feature is NOT associated with Gram-positive bacteria?

<p>Outer lipid membrane (B)</p> Signup and view all the answers

What type of structure do flagella represent in bacteria?

<p>Motility appendages (B)</p> Signup and view all the answers

Flashcards

Archaea

A group of single-celled organisms that differ from bacteria in their lack of peptidoglycan in their cell walls and their unique enzymes that can withstand extreme environments.

Methanogens

A type of Archaea that produces methane gas as a byproduct of energy generation. They live in oxygen-poor environments like sediments and animal digestive systems.

Halophiles

A type of Archaea that thrives in extremely salty environments, such as salt lakes and salt flats. They use energy from sunlight and need oxygen for respiration.

Extreme Thermophiles

A type of Archaea that enjoys exceptionally hot temperatures, thriving in environments like hot springs and hydrothermal vents. They can grow best between 70°C to 95°C.

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Psychrophiles

A type of Archaea that prefers chilly environments, such as Arctic oceans and deep ocean trenches, where temperatures reach -10°C to -20°C.

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What are thermoacidophiles?

A type of bacteria that thrives in extremely acidic and hot environments, often found in geysers and deep sea vents.

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What are Proteobacteria?

A large and diverse group of bacteria that includes a wide range of species, including those that cause diseases like bubonic plague, gonorrhea, and dysentery.

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What are Cyanobacteria?

A group of photosynthetic bacteria that are believed to be the ancestors of chloroplasts, the organelles responsible for photosynthesis in plants.

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What are Gram-positive bacteria?

A diverse group of bacteria that can be both beneficial and harmful. They are commonly found in food production, but also cause diseases.

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What is Gram staining?

The process of staining bacteria to differentiate them based on their cell wall structure.

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What are Gram-negative bacteria?

Bacteria with complex cell walls, containing a smaller amount of peptidoglycan and an additional outer membrane.

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What are pili?

Small, hair-like structures made of proteins that help bacteria adhere to surfaces and other cells.

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What is a flagellum?

Whip-like structures used by bacteria for movement.

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Bacterial Cell Wall

A rigid, protective layer that surrounds bacterial cells. It's mainly composed of peptidoglycan, a complex sugar molecule.

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Bacterial Cell Membrane

A thin, flexible membrane that encloses the cytoplasm of bacterial cells. It controls the movement of substances in and out of the cell.

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Bacterial Chromosome

A single loop of DNA that contains the essential genetic information for a bacterium.

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Bacterial Plasmid

A small, circular piece of DNA found in bacteria. It often carries genes that give bacteria resistance to antibiotics.

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Bacterial Ribosomes

Tiny structures in bacterial cells that manufacture proteins. They read the information encoded in DNA and build proteins based on that information.

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Bacterial Cytoplasm

The fluid-filled space inside the bacterial cell membrane. It contains the bacterial chromosome, ribosomes, and other essential components.

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Autotrophic Bacteria

A metabolic strategy where some bacteria produce organic molecules from inorganic sources, using energy from sunlight, chemicals, or other inorganic materials.

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Heterotrophic Bacteria

A metabolic strategy where most bacteria obtain their energy and carbon from consuming organic compounds produced by other organisms, like dead plants or animals.

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What are endospores?

Bacteria can form resistant structures called endospores that allow them to survive extreme conditions.

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How do bacteria form endospores?

When a bacteria cell is under stress, it forms a protective casing called an endospore around its DNA. This endospore can withstand harsh environments for long periods.

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How do bacteria reproduce?

Bacteria reproduce asexually through binary fission, where one cell divides into two identical daughter cells. This process involves replicating DNA, elongating the cell, and forming a septum to separate the two new cells.

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What is bacterial conjugation?

In conjugation, two bacteria share genetic information through direct contact. One bacterial cell copies genetic material from its plasmid and transfers it to another cell via pili.

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What is bacterial transformation?

Transformation involves the transfer of genetic material from a dead bacterium to a living one. The DNA can be a complete strand or fragments.

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Horizontal Gene Transfer

The process by which bacteria can transfer genetic material, including genes for antibiotic resistance, from one bacterium to another, often through direct contact or via structures called pili.

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Antibiotic Resistance

The ability of a bacterium to survive and reproduce in the presence of an antibiotic, which would normally kill it. This is often due to mutations in bacterial genes that allow them to resist the antibiotic's effects.

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Why antibiotics don't work for viruses

Antibiotics are only effective against living pathogens, like bacteria. They do not work against viruses, which are non-living infectious agents.

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Why finishing an antibiotic is important

When a patient stops taking their antibiotics prematurely, before the entire population of bacteria is eliminated, the remaining bacteria, particularly those resistant to the antibiotic, can survive and reproduce, leading to a more resistant population.

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How antibiotics can backfire

Introducing antibiotics can actually strengthen the bacterial population as a whole, because it eliminates the weaker, more susceptible bacteria, leaving behind the stronger, more resistant bacteria to reproduce and dominate.

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Study Notes

Prokaryotes: Archaea & Eubacteria

  • Prokaryotes are a domain of single-celled organisms that lack a nucleus and other membrane-bound organelles.
  • Archaea and Eubacteria are two domains of prokaryotes
  • Archaea differ from Eubacteria in their cell wall and cell membrane structure, as archaea do not contain peptidoglycan.
  • Archaea thrive in extreme environments.

Domain Archaea

  • Archaea is a kingdom that contains organisms that are prokaryotic.
  • Archaea differ from eubacteria due to the absence of peptidoglycan in their cell walls and membranes
  • Archaea contain specialized enzymes that are not denatured by their environment.
  • Archaea encompass three branches: Euryarchaeota, Crenarchaeota, and Korarchaeota.
  • Examples of specific archaea types and their environments include:
    • Methanogens: live in low oxygen environments (e.g., sediments, digestive tracts of herbivores), generate methane gas.
    • Halophiles: live in highly saline environments.
    • Extreme thermophiles: live in extremely hot environments (e.g., hot springs, hydrothermal vents), optimal growth temperature between 70°C to 95°C
    • Psychrophiles: live in cold environments (e.g., Arctic oceans) and have optimal growth temperature between -10°C to -20°C.

Domain Eubacteria

  • This domain contains the kingdom of bacteria.
  • Eubacteria are often simply referred to as bacteria
  • Eubacteria include twelve branches
  • Some examples of bacteria branches are: Proteobacteria, Cyanobacteria, Gram-positive bacteria, Spirochetes, and Chlamydias

Important Groups of Eubacteria: Key Features

  • Proteobacteria: Ancestor of mitochondria; some are photosynthetic or nitrogen-fixing organisms. Several cause diseases (e.g., bubonic plague, gonorrhea).
  • Cyanobacteria: Ancestor of chloroplasts; photosynthetic
  • Gram-positive bacteria: Commonly found in food production or causing diseases.

Gram Staining

  • Gram staining differentiates bacteria based on cell wall structure.
  • Gram-positive bacteria have thick cell walls with peptidoglycan, which retain the crystal violet stain
  • Gram-negative bacteria have thinner cell walls with an outer membrane and less peptidoglycan, which do not retain the crystal violet stain.
  • Gram-negative bacteria are often more resistant to antibiotics.

Bacterial Shapes

  • Bacteria can be classified by shape:
    • Coccus (round)
    • Bacillus (rod)
    • Spirillum (spiral)
  • Bacteria can also be grouped by their arrangement (if forming chains or clusters)

Why Bacteria are Successful

  • Bacteria exhibit diversity in metabolism (autotrophic, heterotrophic).
  • Bacteria have different oxygen requirements (obligate aerobes, facultative anaerobes, obligate anaerobes).
  • Bacteria occupy many ecological niches (producers, decomposers, symbiotic relationships).
  • Some bacteria can form endospores, protective structures allowing them to withstand environmental stressors

Bacterial Reproduction

  • Bacteria primarily reproduce asexually through binary fission (one cell splits into two identical cells)
  • Bacteria exhibit horizontal gene transfer via conjugation, transformation, and transduction

Antibiotics

  • Antibiotics are effective against bacteria, but not viruses
  • Exposing bacteria to antibiotics selects for antibiotic resistance genes.
  • Proper antibiotic use and patient adherence to the full prescription are essential for limiting antibiotic resistance.

Importance of Bacteria to Health

  • Bacteria are important to the ecosystem and human health, playing roles as producers, decomposers, and in forming symbiotic relationships.

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The Prokaryotes Archaea & Eubacteria PDF

Description

This quiz explores the fascinating world of prokaryotes, focusing on the two domains: Archaea and Eubacteria. It covers their structural differences, extreme environments where Archaea thrive, and specific types of Archaea. Test your knowledge on these unique microorganisms and their classifications.

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