1. Arcahaea Eubacteria Eukarya
Three Domains of Life

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

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

4. 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

5. 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

6. '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.

7. EXTREME CONDITIONS

8. 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

9. 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.

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

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

12. 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.

13. 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

14. Basic Archaea Cell Structure

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

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

17. 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

19. 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.

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

21. 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

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

23. 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.