UNIT 10 A PART 1 Kingdoms and Domains UNIT 10 A PART 1 Kingdoms and Domains

Categories of Biological Classification Taxonomy is the science of naming and classifying organisms. In the 1750s, Swedish biologist Carl Linnaeus developed a new system to name and classify organisms. This system is still in use today.

Scientific Names Linnaeus included a two-word Latin name for each species. This system is known as binomial nomenclature. Binomial nomenclature is a system for giving each organism a two-word scientific name. An example of binomial nomenclature is the two-part scientific name for the common house cat – Felix catus.

Scientific Names The unique two-part name for a species is referred to as its scientific name. The scientific name of an organism consists of its two-part (binomial) name known as the genus species name. The genus species name is always italicized or underlined.

Scientific Names The first word in a scientific name is the genus to which the organism belongs. The first letter of the genus name is always capitalized. – Example: Felix catus – Felix is the genus name and is capitalized. Organisms in a genus share important characteristics and are closely related.

Scientific Names The second word in a scientific name is called a species. A species is the basic biological unit in the Linnaean system of classification that identifies one particular kind of organism within the genus. The first letter of the species name is always lowercase. – Example: Felix catus – catus is the species name and is written in lowercase letters.

Classification Levels Linnaeus worked out a broad system of classification for plants and animals in which an organism’s form and structure are the basis for arranging specimens in a collection. There are eight levels in today’s classification pyramid. The levels from largest to smallest are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Classification Levels All living things are grouped into one of three Domains: Archaea, Bacteria, and Eukarya. There are six Kingdoms: 1.) Eubacteria ( Domain Bacteria ) 2.) Archaebacteria ( Domain Archaea ) 3.) Protists 4.) Plants 5.) Fungi 6.) Animals (Domain Eukarya)

The 6 Kingdoms of Life Protista is the only kingdom that contains both unicellular and multicellular organisms.

This pyramid shows the Grizzly bear classified from Kingdom to Genus species name.

Evolutionary History Classification based on similarities should reflect an organism’s phylogeny, or evolutionary history. However, not all features are inherited from a common ancestor. Organisms that appear similar may not share a recent common ancestor.

These organisms appear similar, but do not share a recent common ancestor.

Cladistics Cladistics is a method of analysis that reconstructs phylogenies by inferring relationships based on shared characters. Cladistics can be used to hypothesize the sequence in which different groups of organisms evolved. Cladistics focuses on the nature of the characters in different groups of organisms.

Cladistics An ancestral character is a character that evolved in a common ancestor of both mammals. When considering the relationship between birds and mammals, a backbone is an example of an ancestral character. A derived character is a character that evolved in an ancestor of one group, but not the other. An example of a derived character when considering birds and mammals is that feathers evolved in an ancestor of birds, but was not also ancestral to mammals.

Cladograms A biologists using cladistics constructs a branching diagram called a cladogram which shows the evolutionary relationships among groups of organisms. Organisms that share derived characteristics are grouped together on the cladogram, and new derived characters will appear on the cladogram as groups evolve.

a cladogram

Phylogenetic Trees Evolutionary relationships can be displayed in a branching diagram called a phylogenetic tree. A phylogenetic tree is a branching diagram that shows how organisms are related through evolution. A phylogenetic tree and a cladogram are similar in that each represents a hypothesis of evolutionary history which must be inferred because it was not observed.

This phylogenetic tree focuses on the relationships between marine organisms.

The 3 Domains of Life This phylogenetic tree is based on rRNA sequences that demonstrate the division of all living things into three broad domains. All living organisms are classified into three superkingdoms or domains : 1.) Archaea, 2.) Bacteria, and 3.) Eukarya.

The Kingdoms of Life Biologists have organized living things into large groups called Kingdoms. Biologists group organisms into six kingdoms based on RNA and DNA sequencing and similarities: 1.Cell Type –Organisms are either prokaryotes or eukaryotes. Scientists generally recognize two kingdoms of prokaryotes and four kingdoms of eukaryotes. 2.Cell Walls − In four of the six kingdoms organisms have cell walls. In one of the six kingdoms, organisms lack cell walls. In the remaining kingdom, some organisms have cell walls and some do not. 3.Body Type –Organisms are either unicellular or multicellular. 4.Nutrition –Organisms are either autotrophs or heterotrophs based on how they obtain nutrition.

Kingdom and Domain Characteristics DomainKingdomCharacteristics Cell type Cell Structure Body TypeNutritionExample BacteriaEubacteriaProkaryotic Cell Wall, Peptidoglycan Unicellular Autotrophic and Heterotrophic Enterobacteria Spirochetes ArchaeaArchaebacteriaProkaryotic Cell Wall, No Peptidoglycan Unicellular Autotrophic and Heterotrophic Methanogens EukaryaProtistaEukaryoticMixed Unicellular and Multicellular Autotrophic and Heterotrophic Amoebas Euglenas Kelps EukaryaFungiEukaryotic Cell Wall, Chitin Unicellular and Multicellular Heterotrophic Yeasts Mushrooms EukaryaPlantaeEukaryotic Cell Wall, Cellulose MulticellularAutotrophic Ferns Pine trees EukaryaAnimaliaEukaryoticNo Cell WallMulticellularHeterotrophic Birds Earthworms

Colonial Organisms A colonial organism is a group of cells that are permanently associated but do not communicate with one another. Aggregations –An aggregation is a temporary collection of cells that come together for a period of time and then separate. True Multicellularity –A multicellular organism is an organism composed of many cells that are permanently associated with one another. –This enables cells to specialize in different functions. Complex Multicellularity –Plants and animals have complex multicellularity. –The specialized cells of most plants and animals are organized into structures called tissues and organs.

The Three Domains of Life

The 3 Domains of Life The domain thought to be the oldest is Bacteria, which is composed of the organisms in the kingdom Eubacteria. Archaea is the second prokaryotic domain and is also composed of single kingdom Archaebacteria. The third domain, Eukarya, contains all four of the eukaryotic kingdoms: 1.) Animalia (animals), 2.) Fungi (fungi), 3.) Plantae (plants), and 4.) Protista (protists).

The Domain Bacteria The Domain Bacteria contains a single kingdom, Eubacteria. Some scientists just call this kingdom Bacteria. Bacteria are prokaryotes and have no internal compartments and no nuclear membranes. Bacteria are found in practically every environment on Earth.

Characteristics of Bacteria Bacteria have strong exterior cell walls made of carbohydrate strands cross-linked by short peptide bridges.

Kinds of Bacteria Some bacteria can cause disease, while others are used by humans to process food. Bacteria are also used to control agricultural pests, to produce various chemicals, and perform genetic engineering. Some bacteria obtain energy from inorganic compounds such as hydrogen sulfide, ammonia, and methane (chemosynthesis).

Kinds of Bacteria Some bacteria are photosynthetic and are found in ocean and freshwater ecosystems. Some heterotrophic bacteria are able to live in the absence of oxygen (or anaerobic ). Heterotrophic bacteria are also important decomposers and help to recycle phosphorus and other minerals back to the soil.

Shapes of Bacteria A bacterial cell is usually one of three basic shapes: coccus - round-shaped bacillus – rod-shaped spirillum – spiral-shaped round rod-shaped spiral-shaped

Members of the Kingdom Eubacteria have a cell wall. Outside the cell wall and membrane, many bacteria have a gel-like layer called a capsule. Members of Kingdom Archaebacteria often lack cell walls. Some bacteria form thick-walled endospores around their chromosomes and a small bit of cytoplasm when they are exposed to harsh conditions. This also makes these bacteria resistant to heat and cold, and more difficult to destroy. A few kinds of bacteria aggregate (or come together temporarily) into strands.

The Domain Archaea The Domain Archaea contains a single kingdom, Archaebacteria. Archaebacteria are prokaryotes that have diverged very early from bacteria. They are more closely related to eukaryotes than to bacteria.

Characteristics of Archaebacteria Cell Wall and Membrane The cell walls of archaebacteria do not contain carbohydrates like the cell walls of bacteria. Archaebacteria contain lipids very different from those of bacteria or eukaryotes. Gene Structure and Translation The ribosomal proteins of archaebacteria are very similar to those of eukaryotes and different from those of bacteria.

Kinds of Archaebacteria Methanogens –These archaebacteria obtain energy by combining hydrogen gas and carbon dioxide to form methane gas. –Methanogens live deep in the mud of swamps and are poisoned by even traces of oxygen. Extremophiles –A group of extremophiles called Thermophiles lives in very hot places. – Halophiles inhabit very salty lakes that can be three times as salty as seawater. –Other extremophiles live in very acidic places or under enormous pressure. Nonextreme Archaebacteria –Nonextreme archaebacteria grow in all the same environments that bacteria do.

The Domain Eukarya Eukarya is made up of four kingdoms: – Protista – Fungi – Plantae – Animalia Members of this domain are all eukaryotes.

Characteristics of Eukarya Highly Organized Cell Interior –All eukaryotes have cells with a nucleus and other internal compartments. Multicellularity –The activities of individual cells are coordinated and the cells themselves are in contact with each other, which occurs only in eukaryotes. Sexual Reproduction – Meiotic cell division forms haploid gametes and two gametes unite to form a diploid cell in fertilization. – Genetic recombination during meiosis and fertilization causes the offspring of eukaryotes to vary widely, providing for evolution.

Kinds of Eukarya A wide variety of eukaryotes are unicellular. Most unicellular eukaryotes are in Kingdom Protista. Protists contain both unicellular and multicellular organisms, and many are aquatic. Fungi are heterotrophs that are mostly multicellular. Many fungi live on and decompose dead organisms, and many others are parasitic.

Kinds of Eukarya Plants and Animals are all multicellular. Almost all plants are autotrophs and have cells with cell walls composed of cellulose. All animals are heterotrophs composed of cells that do not have cell walls. Most plants and animals have tissues and organs.