5/27/2016 CHAPTER 23 CLASSIFICATION OF ORGANISMS

5/27/2016 CLASSIFICATION OF ORGANISMS 30 million species are estimated to live on Earth 30 million species are estimated to live on Earth Only 1.5 million have been named Only 1.5 million have been named Taxonomy – science of naming organisms and grouping them into categories Taxonomy – science of naming organisms and grouping them into categories First developed by Aristotle First developed by Aristotle Modern method developed by Carolus Linnaeus (1758) Modern method developed by Carolus Linnaeus (1758)

5/27/2016 CLASSIFICATION Linnaeus introduced the system of binomial nomenclature. Linnaeus introduced the system of binomial nomenclature. Each organism gets two Latin names (genus and species) Each organism gets two Latin names (genus and species) Species – organisms that can interbreed Species – organisms that can interbreed Genus - many closely related organisms Genus - many closely related organisms Scientific names must be written in italics or must be underlined: Scientific names must be written in italics or must be underlined: genus name is capitalized genus name is capitalized species name is written in lower case species name is written in lower case Homo sapiens or Homo sapiens (humans) Homo sapiens or Homo sapiens (humans)

5/27/2016 CLASSIFICATION OF ORGANISMS Linnaeus also placed organisms into taxonomic categories, the largest of which is the kingdom. Linnaeus also placed organisms into taxonomic categories, the largest of which is the kingdom. Were originally two kingdoms – animals & plants Were originally two kingdoms – animals & plants Recently a grouping above kingdom, called domain, was introduced. Recently a grouping above kingdom, called domain, was introduced. Organisms are now placed into 3 domains: Organisms are now placed into 3 domains: Eubacteria Eubacteria Archaea Archaea Eucarya Eucarya Each domain is subdivided into kingdoms Each domain is subdivided into kingdoms

5/27/2016 CLASSIFICATION OF ORGANISMS Domain Eucarya has 4 kingdoms: Domain Eucarya has 4 kingdoms: Plantae Plantae Animalia Animalia Fungi Fungi Protista Protista A kingdom is further subdivided into a phylum (known as a division in Plantae) A kingdom is further subdivided into a phylum (known as a division in Plantae) Further subdivisions are class, order, family, genus, and species Further subdivisions are class, order, family, genus, and species Hierarchy of classification: domain, kingdom, phylum (division), class, order, family, genus, and species. Hierarchy of classification: domain, kingdom, phylum (division), class, order, family, genus, and species.

5/27/2016 DOMAINS EUBACTERIA AND ARCHAEA Members are commonly known as bacteria Members are commonly known as bacteria Though similar, the two domains have significant differences in metabolic activities. Though similar, the two domains have significant differences in metabolic activities. Some are disease-causing, most are not Some are disease-causing, most are not Differences between the two are based on DNA and RNA sequences Differences between the two are based on DNA and RNA sequences

5/27/2016 EUBACTERIA Three common shapes: Three common shapes: spherical spherical rod rod spiral spiral Classified as prokaryotes, characterized by: Classified as prokaryotes, characterized by: no nucleus no nucleus single, circular strand of DNA single, circular strand of DNA reproduce by binary fission reproduce by binary fission move by flagella or slime they produce move by flagella or slime they produce some are aerobic and others anaerobic some are aerobic and others anaerobic some are parasites some are parasites some are saprophytes (decomposers) some are saprophytes (decomposers)

5/27/2016 BINARY FISSION IN BACTERIA

5/27/2016 ARCHAEA Ancient prokaryotic bacteria, but differ from “regular” bacteria in that: Ancient prokaryotic bacteria, but differ from “regular” bacteria in that: Found in extreme environments such as: Found in extreme environments such as: hot springs at 113º C (above boiling point) hot springs at 113º C (above boiling point) high salt high salt acidic places acidic places Some have special kinds of chlorophyll Some have special kinds of chlorophyll

5/27/2016 EUCARYA Eukaryotic cells are larger than those of prokaryotes (1000 times more volume) Eukaryotic cells are larger than those of prokaryotes (1000 times more volume) Cells have membrane-bound organelles (mitochondria, ER, Golgi, lysosomes, etc.) Cells have membrane-bound organelles (mitochondria, ER, Golgi, lysosomes, etc.) Eucarya are divided into: Eucarya are divided into: Protista Protista Fungi Fungi Plantae Plantae Animalia Animalia

5/27/2016 PROTISTA All are single celled All are single celled Approximately 60,000 different species Approximately 60,000 different species Found in fresh water, marine, and terrestrial habitats Found in fresh water, marine, and terrestrial habitats Many have chlorophyll and are autotrophs Many have chlorophyll and are autotrophs Some reproduce sexually Some reproduce sexually

5/27/2016 FUNGI Have a rigid, thin cell wall composed of chitin; over 70,000 species Have a rigid, thin cell wall composed of chitin; over 70,000 species Do not have chlorophyll; Nonmotile Do not have chlorophyll; Nonmotile Include molds and mushrooms; most are multicellular Include molds and mushrooms; most are multicellular Some are single-celled (yeasts) Some are single-celled (yeasts) Function mainly as decomposers (saprophytes) Function mainly as decomposers (saprophytes) Some are parasitic Some are parasitic

5/27/2016 PLANTAE All are nonmotile, terrestrial, multicellular organisms capable of producing their own food All are nonmotile, terrestrial, multicellular organisms capable of producing their own food Have cellulose in their cell walls Have cellulose in their cell walls 300,000 species have been identified and of these, 85% are flowering plants 300,000 species have been identified and of these, 85% are flowering plants Members of this group can be vascular or nonvascular. Members of this group can be vascular or nonvascular. Some are seed producing, some (ferns) lack seeds Some are seed producing, some (ferns) lack seeds

5/27/2016 PLANTAE Have unique lifecycles: Have unique lifecycles: Haploid gametophyte stage – produces haploid sex cells by mitosis Haploid gametophyte stage – produces haploid sex cells by mitosis Diploid sporophyte stage – produces haploid spores by meiosis. Diploid sporophyte stage – produces haploid spores by meiosis. Capable of both sexual and asexual reproduction Capable of both sexual and asexual reproduction

5/27/2016 ANIMALIA All are heterotrophic and multicellular All are heterotrophic and multicellular All are motile (at least during some part of their life) All are motile (at least during some part of their life) All are capable of reproducing sexually, but some can reproduce asexually All are capable of reproducing sexually, but some can reproduce asexually

5/27/2016 VIRUSES Consist of a nucleic acid core surrounded by a coat of protein (capsid) Consist of a nucleic acid core surrounded by a coat of protein (capsid) Obligate intracellular parasites Obligate intracellular parasites Are not members of any domain or kingdom Are not members of any domain or kingdom Not considered living things Not considered living things Reproduce only when they are in their host cell Reproduce only when they are in their host cell

5/27/2016 VIRUSES Once inside a cell, viral nucleic acids take over the cell and direct it to make more viral particles Once inside a cell, viral nucleic acids take over the cell and direct it to make more viral particles Viruses are host-specific Viruses are host-specific Only infect certain hosts Only infect certain hosts Only infect certain cells Only infect certain cells Have either DNA or RNA as their nucleic acid (not both) Have either DNA or RNA as their nucleic acid (not both) Smallest infectious agents known to humans Smallest infectious agents known to humans

5/27/2016 VIRUSES Viruses bind to the host and either Viruses bind to the host and either Inject its nucleic acid, or Inject its nucleic acid, or Are engulfed through endocytosis Are engulfed through endocytosis In either case, the protein coat is released and the nucleic acid will replicate using the machinery of the host cell. In either case, the protein coat is released and the nucleic acid will replicate using the machinery of the host cell. Once new viral particles are assembled, the host cell is destroyed and new viruses are released to infect other cells. Once new viral particles are assembled, the host cell is destroyed and new viruses are released to infect other cells.

5/27/2016 TYPICAL VIRUSES

5/27/2016 VIRUSES One of the most recent infectious viruses is HIV. One of the most recent infectious viruses is HIV. Only infects humans Only infects humans Causes AIDS Causes AIDS claimed 22 million lives so far claimed 22 million lives so far HIV is a spherical virus containing RNA, a protein shell, and an outer envelope HIV is a spherical virus containing RNA, a protein shell, and an outer envelope Estimated to be over 42,500,000 people infected with the AIDS virus Estimated to be over 42,500,000 people infected with the AIDS virus

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VIROIDS Similar to viruses, but consist only of a single strand of RNA Similar to viruses, but consist only of a single strand of RNA None infect animals None infect animals Mainly infect cultivated crops Mainly infect cultivated crops Potatoes Potatoes Tomatoes Tomatoes Cucumbers Cucumbers Hard to detect Hard to detect Stunted or distorted growth, may or may not cause plant death Stunted or distorted growth, may or may not cause plant death Spread very easily Spread very easily

5/27/2016 PRIONS These are infectious proteins that can be passed from one individual to another These are infectious proteins that can be passed from one individual to another Not species-specific – can be passed between species Not species-specific – can be passed between species Examples include Examples include scrapie in sheep and goats scrapie in sheep and goats mad cow disease in cattle (BSE) mad cow disease in cattle (BSE) chronic wasting disease in deer and elk chronic wasting disease in deer and elk

5/27/2016 PRIONS Epidemic of mad cow disease in Great Britain was apparently caused by the spread of prions from sheep to cattle Epidemic of mad cow disease in Great Britain was apparently caused by the spread of prions from sheep to cattle Prion-caused diseases in humans include: Prion-caused diseases in humans include: Kuru – occurred in Papua New Guinea and spread by eating the brains of their dead Kuru – occurred in Papua New Guinea and spread by eating the brains of their dead Creutzfeldt-Jakob disease – transmitted by surgical instruments and tissue transplants Creutzfeldt-Jakob disease – transmitted by surgical instruments and tissue transplants Similar to mad cow disease Similar to mad cow disease Causes holes in brain matter Causes holes in brain matter

5/27/2016 PRIONS Do not reproduce or replicate as do viruses and viroids Do not reproduce or replicate as do viruses and viroids May cause a normal protein to change shape to that of a dangerous protein May cause a normal protein to change shape to that of a dangerous protein Proteins may stack up and interlock forming plaques Proteins may stack up and interlock forming plaques Finally results in death Finally results in death

5/27/2016 CHAPTER 23 CLASSIFICATION OF ORGANISMS

5/27/2016