Archaea Shauna Menzella

Overview  Domain Archaea wasn’t recognized as a major domain until the 20 th century  Although many books and articles refer to them as “Archaebacteria” the term has since been abandoned  They aren’t bacteria at all- they’re Archaea

What is Archaea?  Similar to bacteria in size and simplicity  Radically different in molecular organization  Intermediate between bacteria and eukaryotes  Unicellular  Inhabiting extreme conditions  Prokaryotes

Structure

Structure (continued)  No nucleus  Do not possess packaging proteins  Possess proteins similar to histones  Single cellular chromosome  Two nucleotides  One type of RNA polymerase  Wide variety of shapes (flat, square, etc.)  Some have flagella

Three Types of Archaea  Crenarchaeota  Characterized by their ability to tolerate extreme temperatures in acidity

Three Types of Archaea (continued)  Euryarchaeota  Includes methane- producers and salt-lovers

Three Types of Archaea (continued)  Korarchaeota  Diverse and widely encompassing group of which little is known

Reproduction  Asexual  Binary or multiple fission  Fragmentation  Budding  Cell division is controlled in a cell cycle  If a species of Archaea exists in more than one form, they will all have the same genetic material

Ecology  Extremophiles  Live in extreme environments and temperatures  Some love the heat, often above 100 degrees C  Geysers at Yellowstone National Park  Some love the cold  Polar seas  Some love salt (halophiles)  Hyper-saline environments