Arcahaea Eubacteria Eukarya Three Domains of Life

Each cell type has unique characteristics Archaea Eukaryotic cell wwwsciencenews.org/view/generic/id/42241/tit . Eubacteria cell Nucleus Organelles

ARCHAEA AND EUBACTERIA Prior to 1970’s, were grouped together as prokaryotes - still see this used.

Archaea Recognized Advances in molecular biology identified Archaea as unique type of cells (Carl Woese, late 70’s, U of Illinois) DNA is very different from bacterial DNA

Characteristics of Archaea Look like Eubacteria rod, spiral, and marble-like shapes. Circular DNA share certain genes with eubacteria so they function similarly in some ways. share genes with eukaryotes Have many genes that are completely unique

'archae' meaning 'ancient' Believed to be the least evolved life forms Called “Extremophiles” due to the extreme conditions they live in similar to the conditions of early Earth Planets with an environment where Archaea might survive include Venus, Jupiter, Saturn, and Jupiter's moon Io, the past environment of Mars.

EXTREME CONDITIONS

Extremeophiles Live at 100 ˚C or greater hot springs, sea vents Are Methanagens, produce methane Extremely alkaline or acid conditions digestive tracts of cows, termites, and marine life Anoxic muds of marshes and sea floors Petroleum deposits deep underground

Archaea do not require sunlight Do not require oxygen Archaea absorbs CO2, N2, or H2S chemically transforms them Give off methane gas or sulfur as a waste product.

Archaea: Morphology Size < one micron (1μ) Shapes vary spherical (coccus) rod-shaped (bacillus) hair-like triangular square

Archaea: Morphology CONTINUDED May have one or more flagella If multiple, they attach on one side

DNA is a single loop called a plasmid tRNAs are unique No internal membranes DNA is a single loop called a plasmid tRNAs are unique "transfer RNA” are important in decoding the message of DNA and in building proteins. Ribosomes are similar to eukaryotes.

ARCHAEA Cell Structure The cell membrane surrounds the cytoplasm Most have a cell wall surrounding cell membrane a semi-rigid layer that helps maintain its shape and chemical equilibrium All three structures (cell wall, cell membrane and cytoplasm) are biochemically unique to Arcahaea

Basic Archaea Cell Structure

EUBACTERIA True Bacteria Found in the air, water, soil and on most moist surfaces •Includes the spirochetes, gram-positive bacteria and cyanobacteria.

Eubacteria shapes Their cells are either spherical, rod-shaped or spiral Coccus are spherical, Bacillus are rod-shaped and Spirillum are spiral.

Bacteria live singly or are found in clusters. Clusters are named based on the arrangement of the bacterial cells. Using cocci as an example: Diplococcus are in sets of two Staphylococci  – a number of cells clustered together (like grapes) Streptococci    – a number of cells arranged in chains

Eubacteria Nutrition Photoautotrophs use the sun to manufacture sugars. Chemoautotrophs need carbon dioxide to obtain energy from inorganic substances. Photoheterotrophs are unique and use light to generate energy but must obtain carbon in organic forms. Chemoheterotrophs use organic molecules such as sugar for energy.

Eubacteria Morphology Vary in size from 1.25 μm to 10μm Largest know is 0.75mm Thiomargarita namibiensis

Eubacteria Morphology Have rigid cell walls and a capsule May have flagella Have pili – extensions of cell wall used to touch/exchange material with other cells No nucleus or membrane bound organelles Have a nucleotide region – circular nucleotides – plasmid

Prokaryotic flagella Nucleoid region (DNA) Plasma membrane Ribosomes Cell wall Capsule Pili

Eukaryotic cells Have a nucleus and membrane bound organelles Are larger than Archaea and Eubacteria Task – Use your textbook to define the terms eukaryotic and prokaryotic. Classify the Archaea and Eubacteria as either eukaryotic or prokaryotic. Justify your answer. Cut and paste activity: Make a poster of the three domains, matching pictures with appropriate descriptions.