TAXONOMY Domains and Kingdoms Why do biologists classify

TAXONOMY Domains and Kingdoms

* Why do biologists classify? q Biologists have identified and named about 2 million species so far. q Scientists estimate that there about 8 million additional species yet to be discovered. q Taxonomy is the discipline where scientists classify and assign each organism a universally accepted name.

* How Has Classification Changed Since the 1700’s? 1753 – Linnaeus 1938 – American introduced his Biologist Herbert What isis another word What is another word two-kingdom Copeland argued for organisms that word for energy one-celled system which that all get by organisms that organisms? included Plantae consuming other prokaryotes lack a nucleus? and Animalia deserved their own organisms? kingdom, Monera 1700 1800 1977 – Research by Carl Woese led scientists to split Monera into two kingdoms: Eubacteria and Archaeabacteria 2000 1866 – German biologist ü Developed a two word naming 1959 Historically, system – American called eukaryotic binomial ecologist Ernst Haeckel. Bacteria proposeslack a nucleus and nomenclature. Robert organisms Whittaker that doproposed not moving single-celled other organelles found inscientific allshould ü Each all species is assigned a two-part that fit into fungi other kingdoms name. be organisms to living the Kingdom things. placed were placed in their inown the Protista kingdom Kingdombecause Protista. of how they feed

1. Is its body made up of 1 cell or many cells? 2. Does its cell(s) have a nucleus or not? 3. Does the organism make its own food or is it a consumer? 4. Does it have a cell wall and, if so, what is it made of? 5. Can it move around freely, or is it stuck to a substrate?

What are the different types of cells? *The cell is the basic structural and functional unit of all known living organisms. *It is the smallest unit of life that is classified as a living thing. *Organisms can be classified as unicellular (its whole body is a single cell; includes bacteria, protista, some fungi) *Or multicellular (many cells make up its body; includes some fungi, all plants and all animals)

What are Prokaryotes and Eukaryotes? q Cells fall into two broad categories, depending on whether they contain a nucleus q Eukaryotes are cells that contain a nucleus and membrane-bound organelles q Eu- means true -karyote means nucleus q Prokaryotes are cells that DO NOT contain a nucleus or membranebound organelles. THESE WERE THE FIRST LIVING THINGS! q Pro- means before -karyote means nucleus

How are Prokaryotes and Eukaryotes similar? q Both eukaryotes and prokaryotes have q a cell membrane q genetic material (DNA) q ribosomes q cytoplasm

* How do Prokaryotes and Eukaryotes differ? Prokaryotes Eukaryotes q Nucleus is absent q Nucleus is present q No membrane-bound organelles q Many membrane-bound organelles q Most 1 -10 um in size q Many 2 -1000 um in size q Evolved 1. 5 billion Evolved 3. 5 billion years ago MORE years ago FIRST LIVING RECENT THINGS q All other kingdoms q Only bacteria and (animal, plant, fungi, archaeabacteria and protist) q

What is The Three-Domain System? *The domain is the largest category of classification. *The three domains are: Eukarya, Bacteria, and Archaea.

Six Kingdoms

*What makes up the Kingdom Archaeabacteria? *Domain: Archaea. *Unicellular *Prokaryotic *Live in some of the most extreme environments on our planet. *Can be aerobic or anaerobic *Have a cell wall *May be producers (chemosynthetic) or consumers. Some use light for energy (not photosynthesis) *Some have flagella or cilia

*What is the Kingdom Eubacteria? *Domain: Bacteria. *Unicellular *Prokaryotic. *Cells have a thick, rigid cell wall containing peptidoglycan. *Ecologically diverse, ranging from free-living soil organisms to deadly parasites. *Can be aerobic or anaerobic *Some have flagella *Some consumers, some photosynthetic, some both.

What makes up the Domain Eukarya? *Consists of all organisms that have a nucleus. *Composed of protists, fungi, plants, and animals.

*Not a fully acceptable kingdom *Eukaryotic *Extremely varied group *Most are unicellular, but some are multicellular. *Some are autotrophs, some are heterotrophs, some are both. *Some can move freely, some cannot. *Some have cell walls, some don’t. *Contain characteristics of plants, animals, and fungi (or a combination). *Organisms are reluctantly classified here if they can’t be placed in any other eukaryotic kingdom.

*What is in the Kingdom Fungi?

*What are the Characteristics of The Kingdom Fungi? *Eukaryotic *Heterotrophs *Cell wall with chitin *Heterotrophs *Most feed on dead or decaying organic matter. Some are parasites. *Non-motile *Most multicellular, some are unicellular

Kingdom Fungi cont… *Fungi secrete digestive enzymes onto their food source (dead plant and animal matter), before absorbing the smaller food molecules into their bodies. *These chemicals break down, or decompose, the dead matter. *This decomposed matter is later absorbed by the fungus or the soil.

*What organisms are in the Kingdom Plantae?

* • • Eukaryotic • They are photosynthetic autotrophs. • • Multicellular Nonmotile, meaning they can not move from place to place. Cell walls contain cellulose

What makes up the Kingdom Animalia?

*What are the characteristics of the Kingdom Animalia? *Eukaryotic *Multicellular *Heterotroph *No cell wall or chloroplasts *Able to move freely at some point in their life cycle.

* What is the three-domain system? q All organisms evolved from cells that formed over 3 b. y. a. q Domain Archaea corresponds to the Kingdom q q Archaebacteria Domain Bacteria corresponds to the Kingdom Eubacteria Domain Eukaria includes the Kingdoms Protista, Fungi, Plantae, and Animalia

* ü SC. 912. L. 15. 5 – Explain the reasons for changes in how organisms are classified.

* How are Linnaean and evolutionary classification different? q Linnaeus grouped species into larger taxa, mainly according to visible similarities and differences. q This approach can cause problems. q The goal of evolutionary biology is to group species into larger categories that reflect lines of evolutionary descent, rather than overall similarities and differences. q Inspired by Darwin’s ideas about descent with modification

* What is cladistic analysis? q Modern evolutionary classification uses a method called cladistic analysis. q Cladistic analysis identifies and considers only those characteristics of organisms that are evolutionary innovations. q Traits that appear in recent parts of a lineage but not in its older members are called derived characters. q Derived characters can be used to construct a cladogram, a diagram that shows the evolutionary relationships among a group of organisms.

* How can I read a cladogram? q A speciation event, in which an ancestral lineage branches into two new lineages, is the basis for each branch point, or node. Each node represents the last point at which the new lineages shared a common ancestor. q The bottom, or “root, ” of the tree represents the common ancestor shared by all organisms on the cladogram.

* How can I read a cladogram? q A cladogram’s branching patterns indicate degrees of relatedness among organisms. q Because lineages 3 and 4 share a common ancestor more recently with each other than they do with lineage 2, you know that lineages 3 and 4 are more closely related to each other than they are with lineage 2. q Likewise, lineages 2, 3, and 4 are more closely related, in terms on ancestry, with each other than any of them is to lineage 1.

* How are DNA sequences used in classification? q Similarities in DNA can be used to help determine classification and evolutionary relationships. q The more similar the DNA sequences of two species, the more recently they share a common ancestor, and the more closely they are related in evolutionary terms. q The more two species have diverged from one another, or changed in comparison to one another during evolution, the less similar their DNA will be.