17 4 Domains and Kingdoms KEY CONCEPT The

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17. 4 Domains and Kingdoms KEY CONCEPT The current tree of life has three

17. 4 Domains and Kingdoms KEY CONCEPT The current tree of life has three domains.

17. 4 Domains and Kingdoms Classification is always a work in progress. • The

17. 4 Domains and Kingdoms Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. – Until 1866: only two kingdoms, Plantae Animalia and Plantae Animalia

17. 4 Domains and Kingdoms Classification is always a work in progress. • The

17. 4 Domains and Kingdoms Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. – Until 1866: only two kingdoms, Plantae Animalia and Plantae Animalia – 1866: all single-celled Protista organisms moved to kingdom Protista

17. 4 Domains and Kingdoms Classification is always a work in progress. • The

17. 4 Domains and Kingdoms Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. – Until 1866: only two kingdoms, Plantae Animalia and Plantae Animalia – 1866: all single-celled Protista organisms moved to kingdom Protista – 1938: prokaryotes moved to kingdom Monera

17. 4 Domains and Kingdoms Classification is always a work in progress. • The

17. 4 Domains and Kingdoms Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. – Until 1866: only two kingdoms, Plantae Animalia and Plantae Animalia – 1866: all single-celled Protista organisms moved to kingdom Protista – 1938: prokaryotes moved to kingdom Monera – 1959: fungi moved to own kingdom Monera Fungi

17. 4 Domains and Kingdoms Classification is always a work in progress. • The

17. 4 Domains and Kingdoms Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. – Until 1866: only two kingdoms, Plantae Animalia and Plantae Animalia – 1866: all single-celled Protista organisms moved to kingdom Protista – 1938: prokaryotes moved to kingdom Monera – 1959: fungi moved to own kingdom Archea Fungi Bacteria – 1977: kingdom Monera split into kingdoms Bacteria and Archaea

17. 4 Domains and Kingdoms The three domains in the tree of life are

17. 4 Domains and Kingdoms The three domains in the tree of life are Bacteria, Archaea, and Eukarya. • Domains are above the kingdom level. – proposed by Carl Woese based on r. RNA studies of prokaryotes – domain model more clearly shows prokaryotic diversity Analyze: Why did Woese propose classifying bacteria and archaea into separate domains, rather than just separate kingdoms? Analyze: Why are protists, plants, fungi and animals classified into the same domain but into different kingdoms? The Tree of Life The most recent classification system divides life into three domains, which include six kingdoms. The distances between branches are proportional to the number of differences in r. RNA sequences among these species.

17. 4 Domains and Kingdoms • Domain Bacteria includes prokaryotes in the kingdom Bacteria.

17. 4 Domains and Kingdoms • Domain Bacteria includes prokaryotes in the kingdom Bacteria. – one of largest groups on Earth – classified by shape, need for oxygen, and diseases caused Figure: The most common shapes of bacteria are rods, spirals and spheres. Many bacteria are named after their shape like this one shown at the right. Spirochaeta: spiral. (colored SEM; magnification 5000 X)

17. 4 Domains and Kingdoms • Domain Archaea includes prokaryotes in the kingdom Archaea.

17. 4 Domains and Kingdoms • Domain Archaea includes prokaryotes in the kingdom Archaea. – cell walls chemically different from bacteria – differences discovered by studying RNA – known for living in extreme environments Figure: Pyrococcus furiosus, can be found in undersea hot vents and in the sand surrounding sulfurous volcanoes. These organisms live without oxygen and can grow in temperatures higher than the boiling point of water. (colored SEM; magnification 6500 X)

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – kingdom Protista

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – kingdom Protista Figure: Zooflagellates have flagella that help them move through water. (colored SEM; magnification unknown)

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – kingdom Protista

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – kingdom Protista – kingdom Plantae Figure: The titan arum plant produces a flower that smells like carrion, or rotting meat. Beetles that eat carrion are attracted by this odor and often wind up pollinating the flower. This ecological relationship is an example of commensalism.

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – kingdom Protista

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – kingdom Protista – kingdom Plantae – kingdom Fungi Figure: Many sac fungi are sac- or cup-shaped or have cupshaped indentations. Sac fungi include moss cup fungi, also known as scarlet elf cups.

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – – kingdom

17. 4 Domains and Kingdoms • Domain Eukarya includes all eukaryotes. – – kingdom Protista kingdom Plantae kingdom Fungi kingdom Animalia Figure: Sea cucumbers are fleshy animals that live on the ocean floor.

17. 4 Domains and Kingdoms • Bacteria and archaea can be difficult to classify.

17. 4 Domains and Kingdoms • Bacteria and archaea can be difficult to classify. – transfer genes among themselves outside of reproduction bridge to transfer DNA – blurs the line between “species” – more research needed to understand prokaryotes Figure: In conjugation, genetic material transfers between prokaryotes, producing genetic variation. A conjugation bridge forms from the donor cell to a recipient cell. (TEM; magnification 6000 X)