Archaea

Archaea

Prokaryotic domain distinct from bacteria and eukaryotes.

Archaea

Found in extreme and non-extreme environments worldwide.

16S rRNA Sequencing

Method used to detect and classify many uncultured archaea.

Uncultured Archaea

Archaea that cannot yet be grown in laboratory culture.

Methanogens

Archaea that produce methane and cannot tolerate oxygen.

Extremophiles

Organisms adapted to extreme environmental conditions.

Extreme Halophiles

Archaea adapted to very high salt concentrations.

Hyperthermophiles

Archaea adapted to extremely high temperatures.

Acidophiles

Archaea adapted to acidic environments.

Psychrophiles

Archaea adapted to very cold environments.

Extremely Halophilic Archaea

Require hypersaline or extremely hypersaline habitats.

Hypersaline Habitat

Environment with very high salt concentration.

Methanogenesis

Production of methane through reduction of carbon dioxide.

Role of Methanogenesis

Final step in anaerobic organic matter degradation.

Oxygen Intolerance

Inability to survive exposure to oxygen.

Extreme Acidophiles

Archaea capable of growth at extremely low pH.

Chemolithotroph

Organism that obtains energy by oxidizing inorganic compounds.

Ferrous Iron Oxidation

Conversion of Fe²⁺ to Fe³⁺ for energy generation.

Thaumarchaeota

Archaeal group abundant in oxygen-rich environments.

Ammonia Oxidation

Conversion of ammonia to nitrite.

Nitrification

Biological oxidation of ammonia into nitrogen compounds.

Hyperthermophile Habitat

Geothermal, volcanic, sulfur-rich, and deep-sea environments.

Growth Above 100°C

Possible under high-pressure conditions.

Thermostable Proteins

Proteins resistant to denaturation at high temperatures.

Thermosome

Archaeal chaperone protein that maintains proper protein folding.

Chaperone Protein

Protein that assists folding and stabilization of other proteins.

High Intracellular K⁺

Helps stabilize DNA at high temperatures.

Reverse DNA Gyrase

Enzyme that introduces positive supercoils into DNA.

Positive Supercoiling

DNA configuration that improves thermal stability.

Biphytanyl Tetraether Lipids

Heat-resistant membrane lipids found in many archaea.

High rRNA G+C Content

Adaptation that improves ribosomal stability at high temperatures.

Archaeal Shapes

Include cocci, rods, curved rods, spirals, branched, and flat forms.

Cocci

Spherical cells.

Rods

Cylindrical cells.

Curved Rods

Bent rod-shaped cells.

Spirals

Helically shaped cells.

Branched Cells

Cells with branching morphology.

Flat Cells

Cells with flattened morphology.

Archaeal Plasma Membrane

Membrane composed of ether-linked lipids.

Phospholipid Monolayer

Single membrane layer formed by tetraether lipids.

Ether Linkage

Chemical bond connecting archaeal lipids to glycerol.

Ester Linkage

Chemical bond characteristic of bacterial and eukaryotic lipids.

Membrane Flexibility

Ability of archaeal membranes to remain functional under extreme conditions.

Membrane Heat Resistance

Resistance of archaeal membranes to thermal damage.

Archaeal Cell Wall

Cell wall lacking peptidoglycan.

S-Layer

Surface layer composed of repeating protein or glycoprotein subunits.

Archaeal Cell Envelope

Outer covering surrounding the archaeal cell.

Simple S-Layer Envelope

Most common archaeal envelope type.

Protein Sheath Envelope

Envelope containing an additional protein covering.

Carbohydrate-Associated Envelope

Envelope containing a carbohydrate layer.

Double Membrane Envelope

Rare archaeal envelope with two membranes.

Archaeal Cytoplasm

Internal region containing cellular structures and biomolecules.

Inclusions

Storage structures within the cytoplasm.

Vacuoles

Membrane-bound storage compartments.

Nucleoid

Region containing the chromosome.

Plasmids

Small circular DNA molecules carrying accessory genes.

Archaeal Cytoskeleton

Protein network providing shape and organization.

Archaeal Ribosomes

Ribosomes more similar to eukaryotic ribosomes than bacterial ribosomes.

Antibiotic Resistance of Archaeal Ribosomes

Unaffected by many antibiotics targeting bacterial ribosomes.

Nucleoid-Associated Proteins

DNA-binding proteins related to eukaryotic histones.

Histones

Proteins involved in DNA packaging.

Nucleosome

DNA wrapped around a histone protein core.

Histone Core

Protein complex containing H2A, H2B, H3, and H4 histones.

Type IV Pili

Surface appendages involved in attachment and motility.

Archaella

ATP-powered motility structures of archaea.

Archaella Structure

Thinner and assembled differently than bacterial flagella.

ATP-Powered Motility

Movement driven directly by ATP hydrolysis.

Proton Motive Force

Electrochemical gradient used by bacterial flagella for movement.#