Origin of Life on Earth Classification of Life

I.Origin of Life on Earth A.Earth’s early atmosphere 1.Probably contained Hydrogen cyanide Carbon dioxide Carbon monoxide Nitrogen Hydrogen sulfide, and Water **No free oxygen

B.Earth formed 4.5 bya & life started 3.5 bya C. Miller-Urey Experiment 1.Stanley Miller & Harold Urey: conducted experiment to recreate how life started 2.They & others made: Amino acids Building blocks of DNA, RNA,& ATP

Miller-Urey Experimental Apparatus:

D. First organisms on Earth were prokaryotes 1. Archae : means “old” or “ancient” First appeared 3.5 billion years ago Called extremophiles because the live in extreme environments similar to conditions of early Earth High salt, high temp., dean ocean Some live in non-extreme environments

2.True Bacteria were next organisms Live all around and in us. Cyanobacteria : made first free oxygen on Earth; began the type of photosynthesis that splits water & makes free oxygen Three common shapes: ―Round: called coccus ―Rod-shaped: called bacillus ―Corkscrew shaped called spiral

The Importance of Classification Taxonomy – grouping and naming organisms by their characteristics and evolutionary history.

I.Aristotle – first to classify organisms A.Organisms were either plant or animal 1.Animals were put into land, water, or air dwellers. 2.Plants were put into three categories based on stems. B.After a period of rapid discovery, new organisms were found that were neither plant nor animal

C.Common names, such as the robin or fir tree were used for more than one species depending on the country. The Great Britain robin is a different bird than the N. American robin. D.Also, common names did not accurately describe the organisms. A jellyfish is not a fish made of jelly!

II.Carolus Linnaeus (1700’s) A.Classification System based on morphology (form or structure of organisms) 1.Developed 7 levels of organization Kingdom (plant or animal) Phylum Class Order Family Genus Species

B.Binomial Nomenclature – process of naming organisms Bi = twoNomial = name 1.Every organism has a scientific name. 1 st part is the organism’s genus (Capitalized) 2 nd part is the species identifier, a descriptive word that matches the species the organism belongs to (not capitalized) Latin Ex: Homo sapiens

2.There are some species that have shown great variation. Botanists sometimes split plant species into varieties. Zoologists split animal species into subspecies. 3.Modern taxonomists still consider morphology (like Linnaeus), but also consider phylogeny (evolutionary history) when classifying organisms.

III.Cladograms – diagrams that show the evolutionary relationships among a group of oganisms

Identify the organism in the table that is least closely related to the others. Use the information in this table to construct a cladogram of these animals.

IV. Now we classify on similarities in DNA & RNA & Proteins A.The genes of many organisms show important similarities at the molecular level. B.Similarities in DNA can be used to help determine classification and evolutionary relationships.

C. Molecular Clock – uses DNA comparisons to estimate how long ago 2 species shared a common ancestor

V.Today’s version of Linnaeus’s Classification System Domain = recognizes differences in cell type Kingdom = 6 kingdoms in 3 domains Phylum = many phyla per kingdom Class Order Family Genus Species = unique group of organisms that can only breed with each other

Kingdoms & Domains I.Updating Classification Systems A.Linnaeus’s 2 Kingdom System 1.Plantae & Animalia – very few species were known at this time. 2.Sponges used to be classified as plants, but with knew knowledge and technology, they are classified as animals.

B.From 2 to 5 Kingdoms 1.In the 1800’s, there was an explosion of discovery. 2.First, the Protista Kingdom was added for unicellular organisms. 3.When eukaryotic and prokaryotic cells were noticed, Kingdom Monera was added. 4.By the 1950’s, 5 Kingdoms were used: Monera, Protista, Fungi, Plantae, Animalia

C.Six Kingdoms 1.In the 1990’s, Kingdom Monera came into question as genetic data showed there were 2 groups of prokaryotes. 2.Kingdom Monera was split: Kingdom Eubacteria and Kingdom Archaebacteria

II.Three (3) Domain System A.Major Characteristics of Organisms 1. Cell Type – prokaryote or eukaryote 2. Cell Walls – cells either have or don’t have 3. Body Type – unicellular or multicellular

4. Nutrition – autotroph or heterotroph 5. Genetics – unique system of DNA, RNA (rRNA), & Proteins

B.The 3 Domains – developed by Carl Woese of the University of Illinois (did work on RNA of all major organism groups) 1.Domain Bacteria – strong cell wall & unique genetic system; same as Kingdom Eubacteria 2.Domain Archae – chemically unique cell wall, membranes, & genetic system; same as Kingdom Archaebacteria 3.Domain Eukarya – all organisms made of eukaryotic cells; Kingdoms Protista, Fungi, Plantae, & Animalia

III.The 6 Kingdoms A.Archaebacteria Unicellular Prokaryote Auto- or Heterotrophic Live in Harsh Conditions: Sulfurous hot springs, salty lakes, anaerobic (no O 2 ), your intestines Archae = ancient; modern Archaebacteria resemble 1 st organisms on Earth

B.Eubacteria Eu = true Unicellular Prokaryote Auto- or Heterotrophic Most bacteria that affect our lives – cause tooth decay, illnesses, curdle dairy, etc. Largest # of organisms than any other kingdom

C.Protista Eukaryotes Mostly unicellular (some multicellular like giant kelp and some algae) Auto- and Heterotrophic Reproduction varies between species Examples: Euglena, Amoebas, Giant Kelp, Algae

1.Classification Problem Some move with flagella, pseudopods or cilia Animal-like, plant-like & fungus-like groups 2.Ecological Importance Important foundation in food chain Produce a lot of oxygen Decomposition Symbiotic relationships: mutualistic, parasitic Medicinal & Industrial uses

D.Fungi Eukaryote Unicellular, Multicellular Heterotrophic (absorption) - feed on decaying organisms Examples: mushrooms, puffballs, mildews, molds

1.Ecological Importance Decomposers Symbiotic -parasitic: on plants and animals -Mutualistic: lichens (fungi & algae) and mycorrhizae (fungi & plants/roots)

E.Plantae Eukaryote Multicellular Mostly Autotrophic Sexual Reproduction Examples: mosses, ferns, conifers, flowering plants

1.Three Traditional Groupings Bryophytes (mossy plants) – nonvascular, seedless Tracheophytes (ferns) – vascular, seedless Seed Plants Gymnosperms – cone-bearing plants Angiosperms – flowering plants

2.Importance to Humans Food source – Wheat, grains, fruits, vegetables Medicine – Aspirin, cancer treatments, stimulants Industry – Agriculture, wood products, cotton

F.Animalia Eukaryotic Multicellular Heterotrophic Symmetrical Bodies, Move Invertebrates: 97% of Animal Kingdom, no backbone Vertebrates: internal skeleton (bone or cartilage)

1.Invertebrates Sponges Cnidarians: jellyfish Worms Mollusks: snails, clams, octopus Arthropods: insects, crustaceans Echinoderms: starfish, sea cucumber

2.Vertebrates = Chordates Fish -Agnatha (jawless fish/lamprey) -Chondrichthyes (sharks, skates, rays) -Osteichthyes (bony fish: bass, tuna, salmon) Amphibians Reptiles Birds Mammals