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Questions and Answers
What is the typical size range for archaeal cells?
What is the typical size range for archaeal cells?
Archaea possess a cell wall made up of peptidoglycan.
Archaea possess a cell wall made up of peptidoglycan.
False (B)
What is the term used to describe organisms that thrive in extreme environments?
What is the term used to describe organisms that thrive in extreme environments?
Extremophiles
The archaeon ________ is known for its ability to survive in extremely salty environments.
The archaeon ________ is known for its ability to survive in extremely salty environments.
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Match the archaeal species with its characteristic environment.
Match the archaeal species with its characteristic environment.
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Which of the following is NOT a characteristic that differentiates Archaea from Bacteria?
Which of the following is NOT a characteristic that differentiates Archaea from Bacteria?
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Archaea are exclusively found in extreme environments, such as hot springs or highly salty lakes.
Archaea are exclusively found in extreme environments, such as hot springs or highly salty lakes.
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What is the primary evidence that supports the three-domain system of classification?
What is the primary evidence that supports the three-domain system of classification?
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The transfer of genetic material between different organisms, often occurring within ancient microbial communities, is known as ______.
The transfer of genetic material between different organisms, often occurring within ancient microbial communities, is known as ______.
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Match the following groups of organisms with their corresponding domain:
Match the following groups of organisms with their corresponding domain:
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Which of these characteristics is common to both bacteria and archaea?
Which of these characteristics is common to both bacteria and archaea?
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The presence of inclusions and plasmids is a characteristic unique to Archaea and not found in bacteria.
The presence of inclusions and plasmids is a characteristic unique to Archaea and not found in bacteria.
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What are the three domains of life?
What are the three domains of life?
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Which type of lipid is found in the plasma membranes of archaea?
Which type of lipid is found in the plasma membranes of archaea?
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The cell wall of bacteria contains peptidoglycan, while archaea do not have peptidoglycan in their cell walls.
The cell wall of bacteria contains peptidoglycan, while archaea do not have peptidoglycan in their cell walls.
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What is the primary difference between flagella and archaella?
What is the primary difference between flagella and archaella?
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Archaea can have a lipid bilayer or a __________.
Archaea can have a lipid bilayer or a __________.
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Match the following properties with their respective types of cells:
Match the following properties with their respective types of cells:
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What feature makes ether linkages in archaea's lipids advantageous?
What feature makes ether linkages in archaea's lipids advantageous?
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Ribosomes of archaea have proteins that are homologous to those found in bacteria.
Ribosomes of archaea have proteins that are homologous to those found in bacteria.
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Name one type of cell wall constituent found in archaea.
Name one type of cell wall constituent found in archaea.
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The __________ serves as a motility structure in archaea, distinct from the bacterial flagellum.
The __________ serves as a motility structure in archaea, distinct from the bacterial flagellum.
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What are the ribosomal proteins in archaea not found in?
What are the ribosomal proteins in archaea not found in?
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Flashcards
Characteristics of Archaea
Characteristics of Archaea
Archaea are unicellular, prokaryotic organisms, microscopic and typically 1-5 μm in size, lacking peptidoglycan in their cell wall.
Shapes of Archaea
Shapes of Archaea
Common shapes of Archaea include cocci (spherical) and bacilli (rod-shaped), resembling bacterial shapes.
Extremophiles
Extremophiles
Archaea are known as extremophiles because they can thrive in harsh conditions such as high temperature, salinity, or acidity.
Comparison with Bacteria
Comparison with Bacteria
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Examples of Archaea
Examples of Archaea
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Archaea
Archaea
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Bacteria
Bacteria
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Plasma membrane composition
Plasma membrane composition
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Cell wall composition
Cell wall composition
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Ribosome size and composition
Ribosome size and composition
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Chromosome structure
Chromosome structure
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Motility
Motility
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Horizontal gene transfer
Horizontal gene transfer
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Archaea Cell Wall
Archaea Cell Wall
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Bacteria Cell Wall
Bacteria Cell Wall
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Motility Structure in Bacteria
Motility Structure in Bacteria
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Motility Structure in Archaea
Motility Structure in Archaea
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Ribosomes in Bacteria
Ribosomes in Bacteria
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Ribosomes in Archaea
Ribosomes in Archaea
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Archaea Protein Diversity
Archaea Protein Diversity
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Ether Linkage Strength
Ether Linkage Strength
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Lipid Structure in Archaea
Lipid Structure in Archaea
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Study Notes
Archaeal Cell Structures
- Archaea are a domain of single-celled microorganisms, distinct from bacteria and eukaryotes.
- Genetic and genomic analysis show Archaea are distinct from both bacteria and eukaryotes.
- They are extremophiles, thriving in harsh environments like high temperatures, salinity, or acidity.
- Archaea have a microscopic size, typically 1-5 µm.
- They are usually unicellular.
- Their cell structure is prokaryotic, meaning they lack a nucleus and membrane-bound organelles.
- Archaeal cell walls lack peptidoglycan.
Learning Objectives
- Learning objectives for understanding archaeal cell structures include: comparing and contrasting archaea and bacteria in terms of shape, plasma membrane composition, cell wall composition, ribosome size and composition, chromosome structure, the presence or absence of inclusions and plasmids, and motility.
Domain Classification
- Organisms are categorized into three domains: Bacteria, Archaea, and Eukarya.
- Archaea and Bacteria are prokaryotic, lacking membrane-bound organelles and a nucleus.
- Eukarya are eukaryotic, having a nucleus and membrane-bound organelles.
Archaeal Examples
- Methanobrevibacter smithii is a methanogen.
- Halobacterium salinarum is a halophile tolerating high salt concentrations.
- Sulfolobus are acidophiles that thrive in acidic environments.
- Acidocaldarius are thermophiles surviving in high temperatures.
Archaeal Characteristics
- Archaea are extremophiles, capable of surviving in harsh conditions.
- They have a unique cell wall structure, lacking peptidoglycan (making them different from bacterial cell walls).
- Their plasma membranes have a specific lipid composition (ether linkages instead of ester linkages found in bacterial membranes). This makes archaea's membranes more resistant to heat.
- Archaeal ribosomes are 70S, similar to those in bacteria.
- Archaeal chromosomes are circular, similar to bacteria, but their ribosomal proteins can vary. Some ribosomal proteins are observed in archaea, some bacteria and some eukaryotes.
Comparison of Bacteria and Archaea
- Similarities: Both are prokaryotic with 70S ribosomes. Both can contain inclusions and plasmids. Both can be circular and linear chromosomes, though archaea more commonly feature circular DNA.
- Differences: The key difference lies in the cell wall composition, and plasma membrane structure. Bacteria have peptidoglycan, Archaea do not. Bacterial plasma membranes have ester linkages; archaea feature ether linkages. Motility structures are also different, with bacteria having flagella, while archaea have archaella.
Archaeal Cell Envelopes
- Archaea exhibit diverse cell envelopes, including an S-layer, a protein sheath (sometimes, a glycoprotein layer), or a polysaccharide layer.
- Some archaea lack an S-layer, sometimes having an intermembrane compartment structure instead.
Additional Properties
- Genetic transfer occurred in early cell communities
- Archaea exhibit horizontal gene transfer.
- Ribosomal proteins in Archaea can show homology to those of eukaryotes. This supports the idea of a common ancestry for these two groups – and is a key finding supporting the three-domain system.
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Description
Test your knowledge on the unique features of Archaea with this quiz! Explore topics like archaeal cell size, extreme environments, and the distinctions between Archaea and Bacteria. Perfect for students of microbiology or anyone interested in these fascinating microorganisms.
