Biological Classification and Viruses

Introduction Common names were not specific enough to meet the scientific needs. 1. improve communication globally 2. avoid confusing names 3. improved accuracy with data

Taxonomy: the science of classifying organisms Carolus Linneaus: (1700s) developed the foundation of the modern classification system Seven levels of order in taxonomy: KPCOFGS Classification specificity: from least specific to most specific (fig. 20.3.1)

Binomial Names Another name used by taxonomists for the modern classification system. Two-part name, genus and species, specific for that organism; in Latin Underlined or italicized Example: Bacillus anthrasis

Method of Classification Structural similarities: similarities in appearance Physiological or biochemical similarities: similarities in how organisms function Used to divide organisms into proper groups and sometimes, over time, these are changed

Prokaryote Kingdoms Prokaryote -no nucleus, no membrane-bound organelles Archaebacteria: like extreme conditions Eubacteria: “bacteria” that can cause human illness -largest number of living organisms ex: page 447

Eukaryote Kingdoms Eukaryote: -membrane-bound nucleus and organelles -much more complex than prokaryote Kingdoms: Protista, Fungi, Plantae, Anamalia

Kingdom Protista characteristics: single-celled or grouped, autotrophs and heterotrophs, generally live in aqueous environments, microscopic size see bottom of page 447

Kingdom Fungi Primarily decomposers Most are multi-cellular Cell walls made of the carbohydrate chitin Mushrooms, puff balls, bread molds 100,000 species -see page 448

Kingdom Plantae Primarily autotrophs Some parasitic forms Multicellular, photosynthetic, cell walls made of cellulose Adapted to all environments and soil conditions Include plants, trees, shrubs, flowers, grasses, mosses, and ferns 350,000 species -see bottom of page 448

Kingdom Animalia characteristics: multicellular, heterotrophic, no cell walls, sexual reproduction, mobile, symmetrical body plan Includes insects, fish, amphibians, birds, reptiles, and mammals Wide range of habitats and modes of locomotion -see page 449

Viruses Smaller than bacteria Not living organisms – called particles -see table at bottom of page 450 Structure:

Incapable of reproducing itself without a host cell. Lytic cycle for DNA virus: virus injects itself into a host cell and takes over the protein synthesis machinery of the cell; it reproduces virus parts and viruses until the cell bursts and releases the viruses to infect new cells. Lysogenic cycle for DNA virus: the viral DNA enters the host cell and integrates with the host cell DNA (provirus or prophage). The viral DNA is replicated with the host cell DNA when the cell divides until something activates the viral DNA; it then enters the lytic cycle.

Lytic cycle for RNA virus: similar to the DNA process; RNA serves as a template to make more capsid proteins Lysogenic cycle for RNA virus: makes DNA from RNA using an enzyme called reverse transcriptase; the DNA then integrates and becomes a prophage until activated.

Viroids and Prions Viroid: simpler than viruses and very small; infect only plants; smallest-known particles able to direct their own replication Prions: simpler than viroids; abnormal forms of proteins; are able to reproduce themselves without a nucleic acid. *not considered “living” because they cannot reproduce independently.

KEY TO FOREST TREES: 1a Leaf edge has no teeth, waves, or lobes go to 2 1b Leaf edge has teeth, waves, or lobes go to 3 2a Leaf has a bristle at its tip shingle oak 2b Leaf has no bristle at its tip go to 4 3a Leaf edge is toothed Lombardy poplar 3b Leaf edge has waves or lobes go to 5 4a Leaf edge is heart-shaped red bud 4b Leaf is not heart-shaped live oak 5a Leaf edge has lobes English oak 5b Leaf edge has waves chestnut oak