Overview of Archaea

Archaea Overview

• Archaea are a distinct domain of life.
• They are prokaryotic microorganisms.
• Archaea have unique cell structure and function.
• Archaea contain extremophiles.
• Archaea inhabit diverse habitats.
• Archaea were originally described as bacteria.
• 16S rRNA sequencing revealed them as a third domain of life.

Archaea Cell Structure

• Archaea are prokaryotes, meaning they lack a nucleus and other membrane-bound organelles.
• Their cells have a circular chromosome.
• They lack cell organelles.
• Archaea cell walls do not contain peptidoglycan.
• Their cell walls can be composed of polysaccharides, proteins, or glycoproteins.
• Some have cell walls complexed with Na+ cations, required for cell wall integrity.
• Archaea cell walls commonly contain an S-layer which is a protein/glycoprotein with a crystalline structure.

Archaea Cell Membranes

• Archaea have unique membrane lipids that are not fatty acids.
• The lipid tails vary in structure.
• An ether linkage bonds the lipid tail and glycerol.
• Lipids can form bi- or mono-layers.
• These unique structures impart distinct membrane properties.

Archaea Cell Morphology

• Archaea range in size from 0.1 to 200 μm.
• Morphology examples include cocci with flagella, short bacilli, and lobed cocci.

Archaea Motility

• Archaea have unique flagella called archaella.
• Archaella rotate to drive motility.
• Archaella are smaller than bacterial flagella.

Archaea Attachment

• Some Archaea have pili-like structures called hami for attachment.
• Hami form networks for biofilm formation.

Archaea Growth

• Archaea reproduce asexually through binary fission.
• Many Archaea cannot be cultured in a lab.

Archaea Metabolism

• Archaea have diverse metabolisms, including aerobic and anaerobic.
• Some are phototrophic, meaning they don't perform photosynthesis, but do CO2 fixation.

Archaea Habitats

• Archaea were first discovered in extreme environments and were called extremophiles.
• Archaea live in habitats with high salt concentrations, (halophiles).
• Others are found in high-temperature environments (hyperthermophiles).
• Archaea are present in locations with extreme pressure (barophiles).
• Some are also found in cold regions (psychrophiles).

Archaea and Life

• Some of the Archaea can survive autoclaving.
• The upper temperature limit for life is under debate.
• Could archaea dominate Earth's future?
• Did life on Earth originate from outer space?
• Could life exist on other planets?

This quiz explores the distinct domain of Archaea, focusing on their unique cell structure and function. Learn about their prokaryotic nature, unique cell walls, and specialized membranes. Challenge your understanding of these extremophiles and their diverse habitats.