Tuesday, March 22, 2016

Chapter 17: Section 3: Modern Classification

The phylogenetic analysis of RNA nucleotide sequences by Carl Woese led to a new version of " The tree of life".  This now contained three domains, and 6 kingdoms. 

Three Domains: Bacteria, Archaea, and Eukarya

Domain Bacteria : Each bacteria has a cell wall, a plasma membrane, a cytoplasm lacking complex organelles, and at least one circular chromosome. ( With Kingdom Eubacteria)

  • small
  • single-celled
  •  prokaryotic 
  • usually have a cell wall 
  • usually reproduce by binary fission 
*The oldest known fossils of cells appear to be bacterial cells 

Domain Archaea: Found in extreme environments, scientists think that they were among the first organisms on Earth because of their unique adaptations ( With Kingdom Archaebacteria) 
  • single celled
  • prokaryotic
  • distinctive cell membranes
  • unique biochemical properties 
  • some are autotrophic and are able to produce food by chemosynthesis
Domain Eukarya: 
(Includes the kingdoms Protista, Fungi, Plantae, and anamalia) 
  • Eukaryotic cells
  • large cells 
  • true nucleus
  • complex organelles
Kingdoms: Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Anamalia

Kingdom Eubacteria: Prokaryotic cells, cell walls containing peptidoglycan, cell membranes containing fatty acids, unicellular, heterotrophic and autotrophic by either photosynthesis or chemosynthesis

Kingdom Archaebacteria: means ancient bacteria, Prokaryotic cells, cell walls lacking peptidoglycan, cell walls containing hydrocarbons, unicellular, heterotrophic, autotrophic by chemosynthesis 

Kingdom Protista: Protists, eukaryotic cells that are not plant, animals, or fungi. 

Kingdom Fungi: Eukaryotic cells, Unicellular or multicellular, gain nutrients by absorbing rather than ingesting, cell walls made of chitin, cell membranes contain fatty acids. 

Kingdom Plantae: Eukaryotic, Multicellular plants, autotrophic, cell walls from cellulose,
cell membranes contain fatty acids 

Kingdom Animalia: Eukaryotic, Multicellular, heterotrophic, symmetrical body organization 

Chapter 17: Section 2: Systematics

Systematics: Classifying organisms in terms of their natural relationships
  •  A modern approach to taxonomy 
Biologists today may try to combine several systems of classification. However, most use Phylogenetics. 

Phylogenetic: The analysis of the evolutionary or ancestral relationships among taxa. 
Phylogenetic Diagrams: Shows how closely organisms within a subset of taxa are related, based on hypothesises. 
  • Several types of evidence are used to hypothesize, Including: Visible similarities, Embryonic development, Patterns of similar chromosomes, and Dna or Rna. 
  • The greater the number of homologous structures, the more closely related organisms are. 

 Cladistics: A system, of phylogenetic analysis that uses shared and derived characters as the only criteria for grouping taxa. 
                            Shared character:  A feature that all members of a group have in common
                         Derived character: A feature that evolved only within the group under consideration 
Clade: The group of organisms that includes an ancestor and all of it's descendants 
Molecular Cladistics: ( such as similar amino acids or nucleotide sequences), as well as chromosome comparisons, can help determine common ancestry 
Chromosomes: analyzing karyotypes can provide more information on evolutionary relationships , and are  independent of physical similarities and molecular data

Chapter 17: Classification

Biodiversity: the variety of organisms considered ay all levels from populations to ecosystems

What is classification?
Classification is the arrangement of organisms into groups/ categories called taxa, based on their similarities

classification is also known as taxonomy
Taxonomy: The science of describing, naming and classification
Taxon: any particular group within a taxonomic system

Aristotle was the first taxonomist
Naturalists replaces aristotles classification system because it did not adequately cover all organisms and the use of common names was problematic

Carolus linnaeus 1707-1778
18th century taxonomist
Classified organisms by their structure
*Developed naming system still in use today

Levels of classification ( largest to smallest):
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Binomial nomenclature: Each organism receives a scientific name with two parts: the genus name is followed by the species identifier.  ( Written in italics with the genus name Capitalized)

Subspecies: variation of a species that live in a different geographic area.