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MBIO 3401 EXAM 2 NEWEST 2025 ACTUAL
EXAM COMPLETE 100 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED
ANSWERS) |ALREADY GRADED A+|BRAND
NEW!!### Archaea
**QUESTION: What are archaea?**
Answer: Archaea are a group of single-celled microorganisms
that are distinct from both bacteria and eukaryotes. They have unique biochemical and genetic characteristics, including distinct cell membrane lipids and different ribosomal RNA sequences.
**QUESTION: How is archaea similar to eukaryotes and
bacteria?** Answer: Cell Structure: Like bacteria, archaea are prokaryotic, meaning they lack a nucleus and membrane-bound organelles.
Metabolism: Both archaea and bacteria can have diverse
metabolic pathways, including anaerobic processes.
**QUESTION: How is archaea different from eukaryotes and
bacteria?** Answer: Genetics: Archaea share more genetic similarities with eukaryotes, particularly in their transcription and translation
processes. Environment: Many archaea thrive in extreme
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environments (e.g., hot springs, salt lakes), while bacteria are
found in a wider range of habitats. Cell Wall Composition:
Archaea often lack peptidoglycan in their cell walls, which is common in bacteria.
**QUESTION: What are the three major groups of archaea?**
Answer: The domain archaea includes three major phyla: 1.TACK hyperthermophiles which mainly metabolize sulfur, 2.Euryarchaeota which show great metabolism range, 3. DPANN which are many symbionts.
**QUESTION: What are TACK hyperthermophiles, and what
are their characteristics?** Answer: Include desulforococcales: anaerobes that reduce
sulfur, sulfolobales: aerobes that oxidize sulfur, caldisphaerales
and thermoproteales: anaerobic acidophiles. Hyperthermophiles: They thrive in extremely hot environments, often at temperatures above 80°C (176°F), with some species tolerating temperatures exceeding 100°C (212°F). Diverse Metabolic
Pathways: Many TACK hyperthermophiles are autotrophic,
utilizing inorganic compounds (e.g., hydrogen or sulfur) for
energy and carbon fixation. Anaerobic Conditions: They
typically thrive in oxygen-depleted environments. Cell
Membrane: Unique membrane lipids, often featuring ether
bonds instead of ester bonds, which contribute to stability at
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high temperatures. Cell Wall: Varies among species, but some
lack a typical peptidoglycan structure found in bacteria.
**QUESTION: What are Euryarchaeota, and what are their
characteristics?**
Answer: Methanogens, halophiles, thermophiles. Unique
Pathway (methanogenesis): Many members, particularly
methanogens, produce methane as a byproduct of anaerobic respiration, using substrates like carbon dioxide and hydrogen.
Cell Membrane: Like other archaea, they possess unique ether-
linked lipids in their membranes, contributing to stability in
extreme conditions. Cell Wall: Many lack peptidoglycan, which
is characteristic of bacteria, and instead may have diverse structural components, such as proteins or polysaccharides.
Compact Genomes: Generally, Euryarchaeota have compact
genomes with a high density of coding sequences, adapting to their specific environments.
**QUESTION: What are DPANN, and what are their
characteristics?** Answer: Includes many symbionts. Varied Metabolic Pathways: Some members are known to have specialized metabolic pathways, including methanogenesis or sulfur metabolism, but many have limited metabolic capabilities and depend on other
organisms for nutrients. Diverse Environments: DPANN
archaea have been found in various habitats, including marine
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environments, hot springs, and even within other
microorganisms (symbiotic relationships). Unique Membranes:
Like other archaea, DPANN members possess unique ether- linked lipids in their membranes, contributing to stability in extreme conditions.
**QUESTION: What genetic traits does archaea possess that
separate them from eukaryotes and bacteria?**
Answer: "Reverse gyrase" enzyme that is responsible for
maintaining positive supercoils at high temperature for hyperthermophiles, distinctive modified bases in their tRNA molecules (archaeosine) which is a guanosine analog.
**QUESTION: What type of cell walls do methanogens and
halophiles possess?**
Answer: Rigid cell walls.
**QUESTION: What archaeota play a major role in the nitrogen
cycle?**
Answer: Thaumarchaeota.
**QUESTION: What is the Asgard superphylum?**
Answer: Closest archaeal relatives of Eukaryotes (actin
cytoskeleton, phagocytosis), includes lokiarchaeota.