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5 kingdom classification system in use through the late 1900s
- monera
- protista
- plantae
- fungi
- animalia
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taxon (taxa) - the named taxonomic unit(s) at any level in this taxonomic hierarchy
"Did King Philip come over for gumbo Sunday?"
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
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how many kingdoms?
- bacterial
- archaean
- protistan
- plantae
- fungi
- animalia
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all living things are either _____ or ______
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taaxonomy
naming and classifying organisms
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systematics
naming and classifying organisms according to their evolutionary relationships
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phylogenetics
reconstructing the evolutionary relationhsips among organisms
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phylogenetic tree
hypothesized genealogy traced back to the last common ancestor (i.e., the most recent) through hierarchical, dichotomous branching
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cladistics
the principles that guide the production of phylogenetic trees, a.k.a., cladograms
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node, brand point, speciation event
point where things intersect like on the graph where they branch off
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lineage or clade
- an entire branch
- the entire graph/branch
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clade
- a monophyletic group
- an ancestral species and all of its descendants
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paraphyletic group lacks...
the common ancestor of species in the group
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cladistic principles allow us to...
construct hypothesized phylogenetic trees
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fossils provide
morphological data for extinct species
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convergent evolution
can provide superficially similar traits that lack homology with one another
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homologous characteristics
share common ancestry
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divergence
lack of similarity among taxa
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analogous characters
do not share common ancestry
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convergence
similarity among taxa
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more homologous characters shared by two species
more closely they are related
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ingroup
group whose relationships we are trying to resolve
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outgroup
- a species known to have an older most recent common ancestor with the ingroup than the ingroup's most recent common ancestor
- helps identify shared ancestral and shared derived characters (unique to a clade)
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parsimonious tree
one that requires the fewest evolutionary events
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three lines of defense against microbial attack
- innate defenses, acquired immunity
- external barriers
- 2 nonspecific internal defenses
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external barriers
- skin
- mucous membranes
- stomach
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skin as an external barrier
- physical barrier to microbia entry
- inhospitable environment for growth
- dry, dead cells at surface
- sweat/sebaceous glands secreting acids and natural antibiotics like lactic acid
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mucous membranes as external barrier
- mucous membraes of respiratory and digestive tracts well-defined
- secretions have antibacterial enzymes
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stomach as external barrier
if microbes swallowed, acids and protein-digesting enzymes destroy them
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what is responsible for many biogeographic distribution patterns?
continental drift
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what results from plate tectonics?
continental drift
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range in size of prokaryotes?
.2-1.0 micrometers in diameter
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range in size of unicellular eukaryotes
10-100 micrometers
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biological entities that are even smaller than bacteria
- viruses
- viroids
- prions
- they are not organisms because they don't have all of the characteristics of living organisms
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viruses
- .05-.2 micrometers
- come in may different shapes
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all virus particles have two parts, some have a third:
- genome
- capsid
- sometimes, an envelope
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genome
- genetic information
- can be either single-stranded or double stranded DNA or RNA
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capsid
protein coat which surrounds and protects the genome
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envelope
membrane (phospholipid bilayer) which surrounds the capsid
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function of a virus
- to take control of a host cell to produe more virus particles
- a biological hijacking
- cell type that a virus will infect is usually very specific and the host species which the virus can infect are often a narrow range
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because viruses require a host for their reproduction,
they are not alive
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viroid
- even simpler and smaller than viruses
- small fragments of single-stranded RNA (either linear or circular) with no protein coat
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function of a viroid
- take over the cell it infects
- plant pathogens which can infect citrus, potatoes, and other crop species
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prions
- unusual infectious particles
- NO GENETIC MATERIAL
- improperly folded version of a natural protein
- this wrongly folded protein causes other copies to convert from the correct folding pattern into the incorect
- as the bad copies accumulate, they result in physical changes in the tissue
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examples of prions:
- linked to degenerative diseases of nervous tissue, especially the brain
- most recently, "mad cow disease"
- Creutzfeldt-Jakob disease and kuru
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origin of prions?
not certain, but probably developed as a by-product of living organisms
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Deinococcus radiodurans
- survive 3000x more radiation than humans
- tolerate extreme dehydration, heat, and cold
- used to "chew up" toxic waste
- "super bacterium"
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prokaryotes domains
Bacteria and Archaea
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prokaryotes have a cell wall
semi-rigid, permeable, made of peptidoglycan (carbohydrate with amino acids attached). Gives bacteria the different types of characteristic shapes
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shapes of prokaryotes
- bacilli: rod-shaped
- cocci: spherical
- spirilla: helical or corkscrew shaped
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surrounding cell walls of some bacteria are:
- either capsules or slime layers composed of polysaccarides and/or proteins
- function is to attach the bacteria to a surface and act as a protective layer
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capsule
highly organized, firmly attached to cell wall
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slime layer
less organized, loosely attached to cell wall
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pili (pilus)
hair-like structures on the surface of certain bacteria which aid in attachment
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rotating flagella
- about half the bacterial species are capable of motion using this
- filaments which extend from the membrane of a cell and are used for cellular locomotion
- structurally different from eukaryotic flagella
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endospore
- protective "resting" structures
- bacteria surrounded by durable cell wall
- resistant to extreme conditions: extreme dehydration, extreme hot or cold, most poisons
- will persist until conditions are favorable then will develop into bacteria
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prokaryotic reproduction
- asexual in the form of binary fission (the entire bacterial chromosome is replicated and passed on to each daughter cell)
- sexual in the form of conjugation using plasmids (some bacteria are able to transfer genetic information between cells by bacterial conjugation: the transfer of genetic information [a plasmid] between two bacteria via a special sex pili. this plasmid is a small double-stranded ring of DNA that carries extrachromosomal genes in some bacteria)
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energy sources of prokaryotes
- autotrophs, using photosynthesis (sunlight) or chemosynthesis (inorganic chemicals)
- heterotrophs, including symbiotes: may occur aerobically or anaerobically, some cases food is obtained through a mutualistic symbiotic relationship in exchange for some other commodity
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most bacteria are harmless (or even beneficial) to humans, some are pathogenic. some diseases caused by pathogenic bacteria are:
- gonorrhea
- syphilis
- TB
- Lyme disease
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antibiotic resistance
- some pathogenic bacteria have developed this because of the widespread use (and misuse) of antibiotics
- 70% of bacterial infections contracted in hospitals are resisted to at least 1 antibiotic
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bacteria vs. archaea
- similar: single-celled, prokaryotes, small size
- different: cell membrane lipids structure, cell wall composition, rRNA subunit sequences,
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protists
- kingdom which represents an unusual mix of organisms
- all eukaryotic, mostly unicellular
- differences between the protists and the rest of the eukaryotes not quite as clear
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three groups of protists
- fungus-like protists: unicellular decomposers
- plant-like protists: (phytoplankton and algae) represent base of most aquatic food webs (lots of photosynthesis and O2 production
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slime molds
- have a two part life cycle in which the cells of many "individuals" form an interactive aggregate which is almost multicellular (mobile feeding stage and stationary reproductive stage with fruiting bodies that produce spores)
- acellular slime molds - division myxomycota
- cellular slime molds - division acrasiomycota
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water molds
(division oomycota): characterized by filamentous bodies and mobile flagellated (can swim) gametes
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acellular slime molds - division myxomycota
- multi-nucleated acellular organisms
- are acellular (without cells) because mobile stage goes through mitosis but not cytokinesis (splitting of cells)
- moves through decaying material engulfing bateria and food particles
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cellular slime molds - division acrasiomycota
- single celled feeding stage
- characterized by individual solitary cells
- amoeboid movement using pseudopodia
- aggregate (clump up) for reproduction during environmental stress
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plant-like protists (phytoplankton and algae)
- dinoflagellates - division pyrrophyta
- diatoms - division chrysophyta
- euglenoids - division euglenophyta
- simple plants (algae)
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dinoflagellates - division pyrrophyta
most are marine, 2 flagella
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diatoms - division chrysophyta
freshwater or marine, glasslike shells with holes to allow for exchange of substances
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euglenoids - division euglenophyta
- most freshwater
- 1-3 flagella
- mostly photosynthetic
- lack cell wall
- have photoreceptor called "eyespot"
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simple plants (algae)
- some species of plant-like protists (the "seaweeds" have just been moved from Kingdom Plantae to Protista
- 3 divisions:
- red algae - division rhodophyta
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