Scientists also Classify Living Organisms Cats, dogs, mammals, pets, friends………

1. Whether they are unicellular or multicellular The most basic classification system is based on Domains and Kingdoms. Organisms are classified into Domains or Kingdoms based on these characteristics: 1. Whether they are unicellular or multicellular 2. _____________________________________ 3. Whether they have a cell wall or cell membrane 4. _____________________________________ 5. _____________________________________ 6. Whether they reproduce sexually or asexually 7. How they tolerate heat, salt, or other extreme conditions See Vocabulary Activity in this Module.

Taxonomy _______________________________________________________________________________________

Three Domains of Life Monophyletic; one c.a.

• Domain Archaea Domain Bacteria Domain Eukarya _________________________________ Contains 1 kingdom – the Archaebacteria Domain Bacteria Includes other members of old kingdom Monera ___________________________ Domain Eukarya Includes all kingdoms composed of organisms made up of eukaryotic cells – Protista – ______________ – Animalia

Prokaryotes Includes the kingdoms Archaea & Bacteria Oldest, structurally-simplest, and most abundant forms of life Important decomposers and symbionts True bacteria; Existed on Earth for 1 billion years before the Eukaryotes appeared

Prokaryotes ______________ No membrane-bound nucleus; instead a single circular chromosome made of DNA _____________________________ Photosynthetic bacteria utilize oxygen or chemical compounds, such as sulfur Although they can transfer genetic material via their plasmids (horizontal gene transfer), however not considered reproduction

Prokaryotic Cell Structure Three basic forms: _________________ Coccus - sphercal or ovoid-shaped __________________

Prokaryotic Cell Structure Prokaryotes have a tough cell wall and other external structures Cell wall consists of _______________; a rigid network of polysaccharide strands cross-linked by peptide side chains; unique to Bacteria Maintains the shape of the cell and protects it from swelling and rupturing

Prokaryotes can have 1 or more flagella (much less complex than in Eukaryotes) Some Prokaryotes possess pilli, which helps fasten cell to host membrane

Domain Archaea Once considered a subdivision of the _________________, now its own domain Like all prokaryotes, Archaea are single-celled microorganisms that lack a nucleus and membrane-bound organelles Best known for the “extremophiles” – Archaea which _______________________environments

Archea - Extremophiles Thermophiles – thrive at 60-80°C (>176°F!) Acidophiles – thrive at pH at or below pH 3 Xerophiles – grow in extremely dry conditions Halophiles – require extremely high concentrations of salt http://www.dpchallenge.com/image.php?IMAGE_ID=448561

Archaea differ from Bacteria in numerous ways Plasma membranes are made of different kinds of lipids RNA and ribosomal proteins more like those of Eukaryotes _________________ (photosynthetic: cyanobacteria and lithotrophs (Nitrosomonas which oxidizes ammonium) Photosynthetic

Domain Bacteria Two types: _____________________ Gram-positive Gram negative _____________________ Refers to the Gram Stain (purple dye) Gram-positive bacteria – possess a thicker peptidoglycan cell wall; _______________ Gram-negative bacteria – contain less peptidoglycan; ________________

Gram-positive and negative

Bacterial Conjugation Transfer of genetic material Horizontal gene transfer NOT sexually (no gametes) Involves cell to cell contact; does not involve fusion of gametes and the creation of a zygote There is not an equal exchange of genetic material, merely the transfer of genetic material from a donor cell to a recipient Often beneficial to the recipient cell – inc. antibiotic resistance or the ability to utilize a new metabolite Transformation – genetic material transfer that does not involve cell to cell contact; direct uptake from environment Tranduction – incorporation of new DNA from virus

Basic Classification Kingdoms: The Domains can also be split into Kingdoms which further divide the organisms by their characteristics.

Domain Eukaryota (Eukarya) __________ Very diverse Unicellular or multicellular ________________ Reproduce sexually or asexually Can be split into 4 Kingdoms- Protista Fungi Plantae Animalia

The 4 Kingdoms in Eukaryota Protista ____________________________ _____________________________ Can be infectious agents Examples: Amoeba Algae Daphnia Plasmodium (causes malaria) Plantae Multicellular green plants Autotrophic through photosynthesis ________________ Mosses Ferns Trees Flowering Plants Fungi _________________ __________________ Decomposers Mushrooms Athlete’s foot Bread Mold Animalia Multicellular Animals ______________ Insects Spiders Crabs Birds Humans

D O M A I N S K I N G D O M S

How would you classify these? A organism that can exist in extremely hot temperatures and that is made of only one cell with no nucleus A green organism growing from the ground that is multicellular and that undergoes photosynthesis; its cells have nuclei and cell walls

Try two more: This microscopic and one-celled organism lives in colonies with millions of others like it. It does not have a nucleus and cannot survive in extreme conditions. It could be an infectious agent. This organism is a multicellular decomposer; its cells have nuclei.