PowerPoint to accompany CONCEPTS IN BIOLOGY Enger • Ross • Bailey CHAPTER 20 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

The classification of organisms The problem with common names Different in every language Different names can be used to identify the same organism. Organisms must have names that all scientists can identify. Naming organisms involves two different activities. Taxonomy The naming of organisms Phylogeny Demonstrating how organisms are related evolutionarily

Garden snake or Garter snake?Jamestown or Jimson weed? Then in 1676, British soldiers were sent to stop the Rebellion of Bacon. Jamestown weed (jimson weed) was boiled to be included in a salad for the soldiers to eat. The hallucinogenic properties of jimsonweed took affect.

Taxonomy The science of naming organisms and grouping them into logical categories Taxis=arrangement Taxon a grouping Scientific names of organisms are in Latin. Capparis cynophallophora, means “dog-penis bearing caper

Taxonomy Organism names follow the binomial system of nomenclature. Introduced by Linnaeus Uses two Latin names The genus and the specific epithet A genus is a group of closely related organisms. A specific epithet identifies the particular species to which the organism belongs. Binomial names are italicized or underlined. The first letter of the genus is capitalized; the specific epithet is not. Thamnophis sirtalis Cattus domesticus Homo sapiens Capparis cynophallophora

Taxonomy Organisms are organized into logical groups. These groups are hierarchical. Domain, kingdom, phylum, class, order, family, genus, species DKPCOFGS

The three domains of life

Classification of humans

Phylogeny The science that explores the evolutionary relationships among organisms. Seeks to reconstruct evolutionary history. Phylogenists use a variety of data to establish evolutionary relationships. Fossils Comparative anatomy studies Life cycle information Biochemical and molecular studies

Fossils Fossils can be placed in a time sequence. Established by the order that the organisms appear in the layers of sediment. Deeper layers were laid down first. Rocks can be aged by analyzing radioactive isotopes. Older rocks have fewer radioactive isotopes.

Comparative anatomy studies The anatomy of fossilized organisms can be compared to that of living organisms. Allows for the classification of fossils Those organisms that have similar structures are presumed to be related. Ontogeny recapitulates phylogeny Examples Plants with flowers are related. Animals with hair and mammary glands are related.

Biochemical and molecular studies New DNA technologies have allowed phylogenists to use DNA sequence comparisons to determine relatedness.

A current phylogenetic tree

A brief survey of the domains of life Eubacteria, Archaea and EuKarya Eubacteria and Archaea are prokaryotic. eukarya is eukaryotic.

Domain Eubacteria “True bacteria” Unicellular Small (1-10 mm) Prokaryotic (no nucleus) Contain a single, circular chromosome Reproduce asexually

Domain eubacteria Cell walls made of peptidoglycan Can be rods, spheres or spirals Varied metabolic requirements

Domain Archaea Unicellular Prokaryotic Single circular chromosomes Have significant differences from both eubacteria and eukarya No peptidoglycan in their cell walls Live in extreme habitats

Domain archaea Metabolically labeled as extremophiles Methanogens Produce methane Found in sewage, guts of ruminants, intestines of humans Halobacteria Live in extremely salty environments Photosynthetic Thermophiles Live in high temperatures or areas with high sulfur concentrations

Habitat for thermophilic archaea

Domain Eukarya Eukaryotic Appear to have evolved through endosymbiosis of prokaryotic cells Larger than prokaryotes Contain specialized membranous organelles

Kingdom protista Most are unicellular. Diverse Some form colonies. Diverse 60,000 species Live in freshwater, marine, terrestrial Some are parasitic, commensalistic or mutualistic. Include algae, protozoa and slime molds Amoeba, Paramecium

A diversity of protista

Kingdom fungi Most are non-motile Have a thin, rigid cell wall composed of chitin Heterotrophic Most are saprophytes (saprotrophic) that secrete enzymes that break down the material they live on. Decomposers Some are parasitic, others are mutualistic. Can form lichens

Kingdom fungi Most are multicellular. Made up of filaments Include A few are unicellular. Yeast Made up of filaments Include Athlete’s foot Plant pathogens Ringworm

Examples of fungi

Kingdom plantae Photosynthetic Likely evolved from green algae Green because of chlorophyll Likely evolved from green algae Non-vascular plants first Then vascular Cone-bearing Flowering

Kingdom plantae Multicellular Contain a cellulose cell wall Photosynthetic

Plant evolution

Kingdom animalia Are thought to have evolved from protozoa Over a million species identified Range from microscopic to very large Common traits Heterotrophs Multicellular Motile Can reproduce sexually

Animal diversity

Acellular infectious particles Living organisms are made of cells. Have cell membranes Use nucleic acids as genetic material Have cytoplasm Contain enzymes Contain ribosomes Use ATP as their source of energy Particles that show some of these characteristics, but not all, are called acellular. Most of these cause disease. Viruses, viroids and prions

Viruses An infectious particle consisting of a nucleic acid core surrounded by a coat of protein. Are obligate intracellular parasites Because they cannot live outside of a living cell Not technically “living” Are extremely small.

Typical viruses

Viral disease

How viruses cause disease Viruses must get their nucleic acids into the cell. Take over host cell to make more virus

How viruses cause disease Viruses don’t have many enzymes. They depend on their hosts to replicate their DNA and make their proteins. After viruses are replicated they leave the cell. Frequently, this process kills the cell.

Viral invasion of a bacterial cell

Prions: Infectious proteins All prion diseases cause brain tissue to become “spongy”. Cause spongiform encephalitis Mad cow (BSE), scrapie (sheep), Creutzfeld-Jakob and Kuru (human) Can be transmitted from one animal to another