Evolution and Taxonomy:
-How new species develop.
-Species: a species is a group of individuals that can interbreed with each other and are reproductively isolated from other such groups.
*The deciding factor is that they only interbreed with each other.
-Like any other area of science, there are exceptions to the rule: some plants, bacteria reproduce asexually.
Two Ways New Species Develop:
1) Allopatric speciation occurs when populations are separated by a geographical barrier that prevents them from reproducing with each other.
a) Variations occur due to different mutations, genetic drift, etc., change from parent type.
2) Sympatric speciation occurs when members of a single population develop a genetic difference that prevents them from reproducing with the parent type. (More common among plants, but also with cichlids in the remote African lake.)
Classification of Organisms:
A. All living organisms have things in common
1) Cells
2) ATP (adenosine triphosphate)
3) Have hereditary material- DNA
4) Evolve
B. Differences Between Organisms (history of classification)
1) The Greeks and Romans started grouping common organisms into genera (genus, singular). Latin for "group."
-Example: Oaks became Quercus (capital first letter, underlined or italicized); cats are Felis.
2) Next the polynomial system evolved
-Scientists used a long string of words to describe the organism (12 or more). This method quickly became cumbersome.
3) Carl Linnaeus started the binomial system in the 1750s.
-Used a two part name for each species
-Standard way of naming organisms used today (always Latin).
-Example: Quercus phellos (Genus, species: Group, kind).
-Escherichia coli, or abbreviated as E. coli.
C. Taxonomy
-The science of classifying living things.
-Hierarchy of groups within groups.
-Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
(Drunk King Phil Came Over For Great Spaghetti!)
Evolutionary Classification:
-Cladogram
1) Based on the order in which species evolved
2) Includes DNA sequencing (is based upon it).
(Review Figure 23.2, pg 456, will be on test)
-Traditional Taxonomy Considers:
1) Key characteristics
2) Uses common descent
3) Amount of adaptive evolutionary change
4) Some bias can come into play because it's a subjective process based on biologists' observation.
5) Historically we did not use DNA sequencing because it simply wasn't available.
(Review also Figure 23.1, pg 454)
3 Domains: Bacteria, Archaea (Prokaryotes), and Eukarya
6 Kingdoms:
1) Archaebacteria (Domain Archaea): Many are anaerobic.
-Three major categories:
a) Methanogens: Use hydrogen gas to reduce carbon dioxide to form methane gas (CH4). Anaerobic, found in swamps, marshes and animals' intestines.
b) Extremophiles: found in extreme conditions of heat, salt, acidic, pressure.
c) Nonextreme: Found in similar conditions as bacteria.
2) Bacteria (Domain Bacteria): Believed to be oldest organism; also most abundant (see page 545). Kingdom Bacteria along with Kingdom Archaebacteria used to be Monera and are prokaryotes.
a) Their cells lack membrane enclosed nucleus and membrane enclosed organelles.
b) They are more metabolically diverse and smaller than eukaryotes.
*The next 4 Kingdoms are eukaryotes:
3) Protista (multi or unicellular)
-Stepping stone from bacteria to everything else.
4) Fungi
5) Plantae
6) Animalia
Viruses
1) Nonliving, simpler than bacteria
2) Acellular
3) Do not metabolize energy, do not have respiration, fermentation, or photosynthesis.
Definition: Nucleic acid encased in a protein coat called a capsid
4) Cannot replicate on their own
5) Uses host to reproduce (parasite)
6) Have DNA or RNA (not both)
7) May be parts of genomes
8) Do not respond to stimuli
(As with everything else in science, there are always a few exceptions)
Examples of viruses: smallpox, chicken pox, shingles, mumps, yellow fever, rabies, aids, flu, polio, some cancers, etc. (Table 21.7, page 527)
Transmissible Spongiform Encephalopathy (TSE's)
-Caused by prions - from protein (proteinaceous infectious particle)
1) Scrapie in sheep
2) Mad Cow Disease in cattle
3) Creutzfeldt-Jakob Disease in humans
4) Chronic Wasting Disease in deer
5) Affects brain and spinal cord by causing Swiss cheese holes
6) No cure
7) Can spread via tissue transplant and food
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