Part I: Classifying Living Things

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(1)Part I: Classifying Living Things.

(2) . . Diversity of organisms: scientists estimate that between ten to thirty million species exist! 18,000 new organisms were added in 2010 alone. In order to make sense of this vast number of species requires a taxonomic organizational structure that allows scientists and students to investigate the types and characteristics of these living things.

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(4)  .     . Characteristics of living things Historical development of our present day taxonomic system. Present day taxonomic methods Classification of Viruses Classification of Plants Classification of Invertebrates Classification of Vertebrates.

(5) . . . . Biologists differentiate living things from non-living things on the basis of various characteristics: Organized systems made up of one or more cells.  In multicellular organelles these cells are often organized further into tissue, organs, and systems. Metabolize matter and energy.  Matter and energy is needed to carry out the chemical reactions that all living things need to do to survive. Interact with their environment and are homeostatic.  Through their activities of obtaining nutrients,.

(6) . . . Grow and develop.  Unicellular organisms grow until it is time for them to divide. Depending on the species this could take hours to a few days.  Multicellular organisms grow and mature. As they mature sex cells develop which enable them to reproduce. Reproduce (biogenesis).  Living things produce living things. It is through the genetic material that the information required for life is passed on to the next generation. Adapt to their surroundings.  Through evolution living things have evolved structures that allow them to exist in varying conditions, e.g. polar bears, birds, etc..

(7) To date scientists have classified approximately 1.5 million organisms. … but scientists estimate there there are over 10 million more to be discovered! .

(8) . . . Biologists place the organisms into groups based on their characteristics. By classifying, biologists can organize living things into groups. This branch of biology is referred to as taxonomy..

(9) . Definition: the branch of biology that deals with the naming and placing of all organisms into groups..

(10) . . . . List examples of classification systems that you use every day. Would a group identified as “flying animals” be useful to a biologist? Explain why or why not. Why is it beneficial for all scientists to use the same classification system? What criteria does a biologist use to distinguish between a living and nonliving thing?.

(11) http://www.mhhe.com/biosci/genbio/espv2/ data/frontpage.html.

(12) . . . Aristotle was the first to use a system of classification for organisms. He placed all organisms into one of two groups. Animals and Plants – he called these Kingdoms..

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(15) . . Theophrastus was a student of Aristotle and he furthered his mentor's work by classifying plants. He classified them according to their stem structure..

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(18) . . . The invention of the microscope and the discovery of microscopic organisms required further classification. These organisms were considered neither plants nor animals. In 1866 Ernst Haeckel added a third Kingdom - he placed single-celled organisms in a kingdom called Protista.

(19) . . . As knowledge about different organisms grew, additional kingdoms were added Mushrooms and mold were first placed in the plant kingdom. It was discovered that they do not carry out photosynthesis and were placed in their own kingdom called Fungi.

(20) . . . The Kingdom Protista required further subdivision because bacteria have a different cell structure than other protists. Bacteria were placed in their own kingdom called Bacteria This kingdom is also referred to as Eubacteria, Prokaryotae, or Monera..

(21) . . Research into bacteria that live in very severe conditions, such as hot or acidic springs, or salt lakes have shown that these organisms have developed unique structures and mechanisms that allow them to survive there. They have reclassified these organism and placed them into their own kingdom called Archaea.

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(24) You discover an unusual organism growing in the bark of a tree. Later, you look at some of its cells under a microscope – it is a multicellular organism that has eukaryotic cells but no chloroplasts. To what kingdom does it belong?.

(25) . . . As a result Biologists have created a new level of classification above kingdom. This new level is called Domain and is based upon the type of cells present There are 3 Domains with 6 Kingdoms distributed through them.

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(27)  . . Aristotle’s system became inadequate. Could no longer use “common names” 1. names differed from one place to next 2. names were not accurate descriptions Linnaeus (mid-1700s) Swedish biologist established a simple system for classifying and naming organisms. He developed a hierarchy (a ranking system) for classifying organisms that is the basis for modern taxonomy..

(28) . . . . . Linnaeus used an organism’s morphology (its form and structure) to classify an organism. His system is still being used today. Linnaeus established a system of groups called taxa. (singular: taxon) Each taxon is a category into which related organisms are placed. Linnaeus used Latin for the names of the taxa, because this was the language of educated people and not an everyday language likely to change. Linnaeus is the Father of Modern Taxonomy..

(29) . . Linnaeus’ classification system is a hierarchy or ranking system. In his system of classification, he ranked the categories from the broadest and most general taxa to the smallest and most specific taxa..

(30) . He then broke down each Kingdom as follows:. 1.. Kingdom Phylum Class Order Family Genus Species. 2. 3. 4. 5. 6. 7..

(31) .  1. 2. 3. 4. 5. 6. 7. 8.. In 1990, Carl Woese introduced a taxon above Kingdom that is called a Domain. Therefore the current taxonomical hierarchy is: Domain Kingdom Mnemonic Devices to remember: Phylum Class Dear King Philip Came Over From Greece Sad Order Dangerous Kids Playing Catch On Freeway Get Squashed Family Dear Kevin’s Poor Cow Only Feels Good Sometimes Genus Species …or make up your own!.

(32)        . Domain Eukarya Kingdom Animalia Phylum Chordata Class Mammalia Order Primates Family Hominidae Genus Homo Species sapien.

(33)        . Domain Eukarya Kingdom Animalia Phylum Chordata Class Mammalia Order Carnivora Family Canidae Genus Canis Species familaris.

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(35) . . Binomial means – “two names“ (nomenclature is another word for “naming”) Taxonomists name organisms by stating the organisms genus followed by a given species name..

(36) .    . The two-term name for the species is always italicized. The genus name is capitalized because there may be many species within that genus. The species name (lowercase) is unique to that individual type of organism. It is usually an adjective that describes that species or is sometimes the last name of the person who identified it. Homo sapien - human Canis familaris - dog Canis lupus – grey wolf Canis latrans - coyote.

(37)  . . Latin is used for naming. Latin at one time was the language of scholars. Today it is used because it avoids having to translate scientific names into the various different languages where different words have different meanings..

(38) .    . . In addition to scientific names organisms are also given common names that are used every day by non-scientific people. Common names can cause confusion! Bakeapple – not an apple! Starfish – not a fish! Cougar, puma and mountain lion are all the same animal! Common names also vary from language to language.

(39) . A universal system of naming allows us to avoid the confusion associated with common names, and tells us something about evolutionary relationships..

(40) .  . . Also called Kingdom Eubacteria, Prokaryotae, or Monera Unicellular organisms Prokaryotic - do not have a nuclear membrane and lack most organelles. They may be photosynthetic, chemosynthetic, or feed by absorption..

(41) . . Chemosynthesis is the production of sugars with energy supplied by the breakdown of other elements. Chemosynthesis of carbohydrates occurs in the nitrite bacteria through the oxidation of ammonia to nitrous acid, and in the nitrate bacteria through the conversion of nitrous into nitric acid..

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(43)  . Also called Archaebacteria These bacteria-like organisms posses a different cell wall composition from bacteria that allows them to survive extreme conditions such as salt lakes, or hot acidic springs.

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(45) . . This domain includes all living organisms that are composed of one or more eukaryotic cells It includes the Kingdoms Protista, Fungi, Plantae, and Animalia.

(46)   . Most are unicellular Eukaryotic May be photosynthetic, may feed by absorption, or may ingest food..

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(48) .   . Most multicellular (although some are unicellular). Eukaryotic cell structure Absorptive heterotrophs Non motile.

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(50)    . Multicellular Eukaryotic Photosynthetic Non motile.

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(52)     . Multicellular Eukaryotic Ingestive heterotrophs Motile Nervous system present.

(53) Invertebrates.

(54) . A dichotomous key is an identification key that uses a series of paired comparisons to sort organisms into smaller and smaller groups.        . used as a way to classify organisms available for almost all living things used by all types of scientists consists of many numbered steps first few steps key on major external features moves from general to specific each step contains two statements of which only one is true about a single organism the true step directs the user to the next step or to the organism.

(55) . . Make a dichotomous key that will identify students in your class. The first question should be the most general/obvious, and the questions will become more specific..

(56) . . . . When biologists classify species into different groups, they are making a hypothesis about their evolutionary history, or phylogeny. A phylogenetic tree is used to show the relationships among various organisms. (See Figure 4-14, p. 116). The bottom of the tree represents a common ancestor – the species above share all of the characteristics of this ancestor. These old characteristics are called primitive characteristics. Primitive characteristics determine the order of the species. Each branch represents a split in which new derived characteristics emerged..

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(58) . . . Cladistics: refers to a classification scheme that is based on phylogeny. It is based on the idea that each group of related species had one common ancestor, and organisms retain some ancestral characteristics and gain some unique derived characteristics as they evolve and diverge from the common ancestor. ( p.117) A cladogram is similar to a phylogenetic tree, but is used to test hypotheses about which species diverged first..

(59) Summary of how organisms are classified. P. 121 - #12.

(60) . . Biologists must look for evidence to determine how organisms are to be classified (grouped). There are six types of evidence that biologists use:.

(61) . Radioactive dating uses the decay of carbon-14 to find the ages of some organisms. They can then tell if they were ancestors of some species..

(62) . . . Structural information is the comparison of bones found in certain animals. For example, the human arm, horse’s leg, bat’s wing, and a whale flipper are all quite similar. They have similar arrangement and the similarities of bone structure indicate the same evolutionary origin..

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(64) . . Comparative embryology is the comparison of early embryonic development. For example, tunicates, in their larval stage, have structures that are similar to tadpoles, such as long dorsal nerve cords and a flexible notochord. They are therefore classified with other vertebrates..

(65) . . Biochemical techniques can look at the arrangement of amino acids in important proteins. Protein comparisons of amino acid sequences are checked for similarities and differences. The blood proteins in horseshoe crab reveal that it is more closely related to spiders than crabs..

(66) . DNA analysis is a good way measuring the closeness of relationships among organisms..

(67) . Based on DNA comparisons, humans are more closely related to chimpanzees than they are to other apes..

(68) . Events, such as the ability to digest certain substances or if an organism is a producer, a consumer, or a decomposer can also be used in classifying organisms..

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