Taxonomic Groups Biology 8(C)

Taxonomic Groups Learning Objectives Compare characteristics of taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals After this lesson you will be able to compare characteristics of taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals.

Taxonomic Groups All living organisms are grouped into one of a few major categories. Most widely accepted classification system used by taxonomists groups organisms into six major groups or kingdoms Archaea Bacteria Protista Fungi Plantae Animalia All living organisms are grouped into one of a few major categories. The most widely accepted classification system used by taxonomists groups organisms into six major groups or kingdoms. These six groups are: archaea, bacteria, protista, fungi, plantae, and animalia.

Image by Wing-Chi Poon [CC-BY-1.0] Archaea Archaea – single-celled microorganisms Characteristics Microscopic Many live in extreme environments Unicellular prokaryotes Unique cell wall Autotrophs or heterotrophs Image by Wing-Chi Poon [CC-BY-1.0] Examples: Methane-producing archaea Sulfur-producing archaea Thermophiles The archaea group contains single-celled microorganisms. Many live in extreme environments such as deep vents or geyser basins, such as the thermophilic bacterial stain seen in the photo taken near a geyser basin. All members of this group are unicellular prokaryotes. Remember that prokaryotic cells do not contain a nucleus or membrane-bound organelles. Archaea have cell walls which are different structurally than bacterial and plant cell walls. However, the function to protect the organism is the same. Some archaea are autotrophs which make their own food. This group is unique in that they use chemicals, not sunlight, to synthesize their own food. Other archaea are heterotrophs which absorb nutrients from other organisms. Examples of archaea are methane-producing archaea, sulfur-producing archaea, and thermophiles. Thermophiles can withstand extreme heat.

Bacteria Bacteria – single-celled microorganisms Characteristics Microscopic Unicellular prokaryotes Cell wall made of peptidoglycan Autotrophs or heterotrophs Examples: E. coli Salmonella Streptococcus Staphylococcus The group known as bacteria contain many different kinds of single-celled microorganisms. On the surface, this group seems very similar to archaea. However, there are structural differences between the two. Archaea are more closely related to eukaryotes than bacteria. All bacteria contain cell walls composed of a protein and carbohydrate matrix, called peptidoglycan. These cell wall are structurally different than archaea or plant cell walls. Some bacteria is this group are autotrophic, meaning that they can produce their own food. Some members contain chlorophyll and perform photosynthesis. Other types of bacteria are heterotrophic and must obtain their energy by absorbing or ingesting their food source. Some examples of bacteria are E. coli, salmonella, streptococcus, and staphylococcus.

Protista Protista – most diverse kingdom Characteristics Unicellular or multicellular Eukaryotes Autotrophic or heterotrophic Some have cell walls Many are microscopic Many are aquatic Some are motile Examples: Algae Paramecia Amoeba Diatoms The group protista is the most widely diverse kingdom. All protists are eukaryotes, which means that their cells contain a nucleus and membrane-bound organelles. Some protists are unicellular while others are multicellular. Some are autotrophs and some are heterotrophs. Some have cells walls and some do not. Many protists are microscopic. However, some types of algae, such as sea kelp, can grow many feet long. Many protists live in aquatic environments. Some have the ability to move in the water by using cilia or flagella to propel themselves. Examples of protists are algae, paramecia, amoeba, and diatoms (shown here).

Image by Maciej Lewandowski [CC-BY-1.0] Fungi Fungi – similar to plants but not photosynthetic Characteristics All eukaryotes Some unicellular Most multicellular Cell wall made of chitin Absorb nutrients Many are saprobes All sessile Image by Maciej Lewandowski [CC-BY-1.0] Examples: Mushrooms Yeasts Molds Fungi are similar to plants but they do not contain chlorophyll and are therefore not photosynthetic. All members are eukaryotic. Some members, such as yeasts, are unicellular, but most fungi species are multicellular. Fungi cells contain cell walls that are composed of the carbohydrate, chitin, instead of cellulose, which is found in plant cell walls. They are heterotrophs since they must absorb their nutrients through their cell walls. Many fungi are saprobes, which means they feed on dead and decaying matter. Many times fungi are found growing on dead and decaying logs. Fungi are sessile. This means that they spend their entire life attached to one location. They do not move around. Examples of fungi are mushrooms such as the ones shown in the photo, yeasts, and molds.

Image by Eric Guinther [CC-BY-1.0] Plantae Plantae – both vascular and nonvascular plants Characteristics All eukaryotes Most multicellular Some unicellular Cell wall made of cellulose Photosynthetic autotrophs Contain chloroplasts Sessile Image by Eric Guinther [CC-BY-1.0] Examples: Mosses Ferns Conifers Flowering plants Kingdom Plantae contains both vascular and nonvascular plants. All members are eukaryotic. Most are multicellular, composed of many eukaryotic cells. However, there are some unicellular plants. All plant cells have protective cell walls composed of the fibrous carbohydrate, cellulose. All plants are photosynthetic autotrophs, meaning that they make their own food by using sunlight to drive the process of photosynthesis. The pigment which absorbs the energy from the sun is chlorophyll, found in chloroplasts within the plant cells. Like fungi, plants are also sessile. Examples of plants are mosses, ferns, conifers such as the ones shown in the photo, and flowering plants.

Image by Eric Guinther [CC-BY-1.0] Animalia Animalia – most complex kingdom Vertebrates Invertebrates Characteristics Multicellular (eukaryotes) No cell walls Heterotrophic Most are motile Image by Eric Guinther [CC-BY-1.0] Examples: Mammals Birds Insects Worms Kingdom Animalia is the most complex group. It includes both invertebrates and vertebrates. Invertebrates do not have a backbone, while vertebrates do possess a backbone. All members are multicellular, composed of many eukaryotic cells. No animal cells contain cell walls. Animals are heterotrophic, which means they receive their nutrients by ingesting other organisms. Most animals are motile, meaning they have the ability to move around. A few invertebrates, such as sea sponges, are an exception. They remain sessile throughout their lives. Examples of animals are mammals, birds, insects, and worms.

Taxonomic Groups Group (Kingdom) Major Characteristics Examples Archaea Prokaryotes, cell wall, may live in extreme environments, unicellular, autotrophs or heterotrophs Methane-producing archaea, thermophiles Bacteria Prokaryotes, cell wall made of peptidoglycan, unicellular, autotrophs or heterotrophs E. coli, salmonella Protista Eukaryotes, unicellular or multicellular, autotrophs or heterotrophs, some have cell wall, many are microscopic Algae, paramecia, euglena, diatoms Fungi Eukaryotes, most are multicellular, cell walls, absorbs nutrients through cell wall, sessile Mushrooms, molds, yeasts Plantae Eukaryotes, most are multicellular, cell walls composed of cellulose, photosynthetic, autotrophs Ferns, mosses, conifers, flowering plants Animalia Eukaryotes, multicellular, heterotrophs, most are motile Mammals, birds, insects, worms, sponges This chart summarizes the major characteristics of the six taxonomic groups.

Taxonomic Groups Learning Objectives Compare characteristics of taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals You should now be able to compare characteristics of taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals.