Archaea, Bacteria, and Eukarya

• Prokaryotic organisms make up two of the three domains of life: Archaebacteria (archaea) and Eubacteria (bacteria).
• Archaea was recognized as a separate domain in the 1990s.
• Archaea's unique genetic material led to its separation from Eubacteria in the late 1970s.
• Genetically, archaea are more closely related to eukarya than bacteria.

Archaebacteria

• Archaea lack a nucleus and organelles, and are believed to be some of the oldest life forms.
• Archaea thrive in extreme conditions such as frozen glaciers and acidic mines.
• Life is divided into three domains: bacteria, archaea, and eukarya.
• Archaea and bacteria are prokaryotic organisms lacking a nucleus or other organelles.
• Carl Woese's ribosomal RNA comparisons revealed key differences among prokaryotic organisms in the late 1970s.
• Woese's work led to archaea being recognized as a distinct domain.
• Archaea share a more recent common ancestor with eukarya but are morphologically more similar to bacteria.

Archaebacteria Characteristics

• Archaea do not have a nucleus or other membrane-bound organelles.
• Archaea size ranges from 1-10 microns, similar to bacteria.
• Archaea reproduce asexually.
• Archaea membrane chemistry is more similar to eukarya than bacteria.

Archaebacteria Cell Structure

• Archaea have a region containing genetic material instead of a nucleus.
• Archaea DNA is circular and within the cytoplasm.
• Archaea plasma membrane, composed of phospholipids, can be a monolayer.
• Monolayer membranes enable archaea to withstand extreme conditions: temperatures, pH, salinity.
• Cell walls protect archaea and provide shape, offering additional protection.
• Pili are tube-like structures that allow cell attachment and DNA transfer.
• Cannulae are unique hollow tube structures used to attach to colonies, found in marine organisms.
• Archaea move using a flagellum, powered by ATP, with clockwise movement moving the cell forward and counterclockwise movement pulling it backward.
• Archaea cells have ribosomes and enzymes, like those found in eukaryotic cells.

Archaebacteria Metabolisms

• Phototrophs obtain energy from sunlight, similarly to photosynthesis.
• Lithotrophs obtain energy by breaking down simple chemicals like sulfur or ammonia.
• Organotrophs obtain energy by breaking down organic material.

Archaebacteria Habitats

• Some archaea are extremophiles, thriving in conditions not conducive to most life forms.
• Thermophiles thrive in high temperatures, such as Crenarchaeota in hydrothermal vents.
• Acidophiles thrive in high acidity conditions.
• Euryarchaeota tolerate salty environments, such as hypersaline lakes.
• Thaumarchaeota are found in soils, and they oxidize ammonia for energy.
• Archaea are also found wherever bacteria exist.

Archaebacteria Reproduction

• Archaea DNA is structured as a single circular chromosome.
• Archaea reproduce via binary fission.
• DNA replicates, creating a duplicate, and attaches to the plasma membrane.
• The parent cell pinches, resulting in two identical daughter cells.

Unique Gene Transcription

• Like bacteria, archaea have a single circular chromosome attached to the plasma membrane.
• Archaea and eukarya share more commonality in transcription and translation than with bacteria.
• Archaea use a single type of RNA polymerase to transcribe all genes.

Role of Archaebacteria in the Environment

• Archaea are abundant in plankton, soils, and bodies of water.
• They play a role in nutrient cycling.
• Habitats include extreme environments and moderate conditions, such as cow stomachs and human guts.
• Archaea are found in plants as part of the microbiome.
• Archaea can assist with nutrient cycling, plant stress responses, and interactions between bacteria and the host organism.

Archaebacteria Species

• Crenarchaeota reside in high temperatures, such as hot springs and hydrothermal vents.
• Metallosphaera sedula is used in biomining which is less harmful to the environment.
• Euryarchaeota, such as Methanomicrobia, produce methane by reducing carbon dioxide.
• Thaumarchaeota are found marine and freshwater environments, soils, and hot springs.
• Thermosphaera aggregans' enzymes are useful in biotechnology and withstand extreme conditions.

Eubacteria

• Though simple, bacteria cells are diverse and common.
• Bacteria found on human skin maintain health.
• Bacteria can be harmful and cause illnesses.
• Bacteria are essential for energy cycling through the ecosystem and act as decomposers and producers.

Classification of Eubacteria

• Eubacteria, or bacteria, are prokaryotic organisms encountered daily.
• These organisms are a separate domain from archaea and eukarya.
• Genetic comparisons showed that these domains split 3 billion years ago according to work published by Carl Woese in 1977.

Eubacteria Characteristics

• Bacteria, like archaea, lack a nucleus.
• Bacteria and archaea have physiological differences

Eubacteria Structure

• Bacteria are prokaryotic organisms without a nucleus or membrane-bound organelles.
• Bacteria have a nucleoid region where genetic material is stored.
• Most bacteria have one chromosome, with genes coding for similar proteins located adjacently.
• Cytoplasm contains RNA molecules, ribosomes, and enzymes.
• Most bacteria are protected by a peptidoglycan cell wall, providing shape and strength.
• Bacteria shapes are rod-shaped, rounded, or spiral-shaped.
• Some bacteria have a capsule for water retention and surface attachment.
• Bacteria have a flagellum, made of protein filaments, for movement.

Eubacteria Metabolisms

• Bacteria are classified by how they obtain energy, metabolizing nearly anything.
• Chemoorganotrophs feed on carbohydrates.
• Chemolithotrophs feed on inorganic molecules.
• Photoautotrophs use sunlight to produce glucose via photosynthesis.

Eubacteria Habitats

• Eubacteria are found in moderate environments.
• They are found in and on other organisms.

Eubacteria Reproduction

• Bacteria reproduce via binary fission, dividing into two daughter cells with identical genetic information.
• Bacteria can transfer genetic material within the same generation.
• DNA is transferred from one cell to another.
• A virus introduces new DNA from its former host cell to its new host cell.
• A bacteria cell picks up genetic material from its environment that may have lived there before.

Role of Eubacteria in Environment

• Bacteria can be found consuming organics that help break down materials.
• They are also found consuming inorganics.
• Bacteria convert sunlight into sugars for energy.
• Bacteria convert atmospheric nitrogen into ammonia for vegetation.

Eubacteria Species

• Lactobacillus acidophilus produces lactic acid, creating yogurt's characteristic flavor and is used to treat gastrointestinal illnesses.
• Pathogenic bacteria cause diseases, acne, strep throat, cholera, and tuberculosis.
• Overgrowth of Bacillus cereus occurs when food is left at room temperature, causing vomiting and diarrhea.
• E. coli grows in undercooked food and contaminated water, causing digestive distress.

Differences Between Archaebacteria and Eubacteria

• Prokaryotic organisms were separated due to differences in ribosomal RNA structure.
• Genetically, archaea are more closely related to eukarya, while morphologically similar to bacteria.
• Bacteria contain peptidoglycan in their cell walls, where some archaea can have a monolayer.
• Monolayers allow archaea to thrive in extreme conditions.
• Bacteria have fatty acid-glycerol esters, while archaea have phytanyl-glyceral ethers.
• Bacteria use fatty acid chains for protection and material transport.
• Bacteria have one type of RNA polymerase, while archaea have multiple.
• Many archaea thrive in extreme environments.
• Archaea do not cause disease in humans, as some bacteria can.

Explore the evolutionary relationships and characteristics that distinguish Archaea, Bacteria, and Eukarya. Learn about cell structures and environments inhabited by archaea. Understand the classification of microorganisms based on cell wall composition and ribosomal RNA sequence.