GENERAL BIOLOGY 2

• Molecular phylogenetics


  The branch of biology that studies the relationships of organisms based on their DNA and protein compositions using computer algorithms
• DNA and protein


  Can be used as derived characters of certain organisms to be classified in the same category
• Molecular clocks


  A model that uses mutation rates to measure evolutionary time
• Two biologists, Linus Pauling and Emile Zuckerkandi, proposed a new method of measuring evolutionary time in the early 1960's by comparing the amount of amino acid differences of hemoglobin with different range of species, they were able to discover how distantly related the two species are
• Mitochondrial DNA (mtDNA)


  DNA present only inside the mitochondria, the organelle responsible for providing every cell's energy
• Nuclear DNA


  The combination of the DNA from the mother and father
• Ribosomal RNA (rRNA)


  Considered for studying distantly related species such as those from different kingdoms and phyla
• It is this molecular clock that CARL WOESE first used to establish that Archea have diverged from a common ancestor with Bacteria almost four billion years ago
• Domains of the Living World

  The phylogenetic analysis of rRNA nucleotide sequences have enabled scientists to establish the new "tree of life" that consists of only three domains aligned with six kingdoms
• Three Domains

  • Bacteria
  • Archaea
  • Eukarya
• The three kingdoms with multicellular and eukaryotic members originate in three separate lines from the Kingdom Protista. With the use of rRNA nucleotide sequence analysis, Carl Woese, in 1977, discovered that prokaryotes have two genetically different groups. His findings guided taxonomists to divide the Kingdom Monera into two kingdoms, called Bacteria and Archea
• Domain Bacteria


  Aligns with Kingdom Eubacteria, which means "True bacteria" in Latin. Members of the Domain Bacteria are prokaryotes whose cells lack a nucleus
• Domain Archea


  Aligns with Kingdom Archaeabacteria, which consists of single-celled prokaryotes with features that have distinctive chemically different cell membranes and cell walls. They are named after the Greek word "archaios" meaning "ancient"
• Archaean groups

  • METHANOGENS - methane-producing archaeans
  • HALOBACTERIA - salt-loving archaeans
  • THERMOPHILES - heat-loving archaeans
• Domain Eukarya


  Includes the kingdoms of PROTISTA, FUNGI, PLANTAE, and ANIMALIA. All members of these kingdoms have eukaryotic cells in their bodies. Eukarya may be single-celled such as most protists, colonial such as the algae, or multicellular like humans
• Scientists claimed that the number of actual species that have been discovered and identified, is close to around 8.7 million with 6.5 million species on land and 2.2 million in oceans (Census of Marine life, August 24, 2011). So far, scientists have only identified, named and classified almost two million kinds of organisms on Earth
• Taxonomy


  Comes from the root word "taxis", which means "arrangement"
• Aristotle's classification system


  • One primeval system developed was based on "harmful" and "nonharmful" organisms or edible or nonedible plants
• Polynomial system of classification


  The simple system of Aristotle's classification was expanded by the Greeks and Romans into basic units- cats, oaks, and horses. These units began to be called as genera, which is the Latin name for "group"
• Before mid-1700s, biologists affixed a series of descriptive terms to the name of the genus if they wanted to refer to a certain kind of organism within it, known as species. These many phrases, starting with the genus, are known as polynomials, which is made up of 12 or more Latin words strung together
• Binomial naming of organisms


  Linnaeus' legacy is the assigning of two Latin names to a certain species, known as binomial nomenclature (bi means "two", nomen means "name" and calatus means "list")
• Binomial nomenclature


  The combination of a genus (plural: genera) and the specific epithet forms the unique scientific name of a certain species
• Rules for writing a scientific name using binomial nomenclature


  • The genus is the 1st name and species is the 2nd name
  • Always capitalize the genus
  • Species name is always lowercase
  • Underlined or italicized written
• Taxonomic ranks


  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Systematics


  A modern approach to classification that focuses on analyzing the diversity of organisms in the context of their natural relationships. It incorporates taxonomy and phylogenetics
• Taxonomy


  The science of describing, naming, and classifying species
• Phylogenetic systematics


  The science that focuses on the evolutionary history of a group of species. It deals with identifying the evolutionary relationships among the many different kinds of life on Earth, both living (extant) and dead (extinct)
• Phylogenetic tree


  An illustration or diagram used to visually present the evolutionary relationships or variability among groups of organisms
• Branch point


  The hierarchical classification of groups is nested within inclusive categories. The point at which is known as the "root" meaning this is the source where all species are derived from
• Cladistics


  A common method used by taxonomists to create an evolutionary tree. This relies on common ancestry as the basis for establishing the classification on how organisms descended from a common ancestor
• Assumptions of cladistics


  • Group of related species descended from a common ancestor
  • Branching patterns symbolize relationships among groups, with new evolutionary groups arising from a common ancestor
  • Characteristics change over time
• Ancestral characters


  Traits inherited from the common ancestor of the group
• Derived characters


  Features that are different from those present in the group
• Cladogram


  A diagram that reconstructs phylogenetic relationships by depicting patterns of shared derived traits among groups of organisms
• Nodes


  Branching points in a cladogram that represent how organisms diverge into two or more species
• Animal specialized structures


  • Cells grow, mature, and undergo differentiation in multicellular animals. Tissues are formed as a result of differentiation. The human body, for example, is made up of more than 200 differentiated cells. A tissue is a group of similar cells that performing a common function
• Four types of animal tissues


  • Epithelial
  • Connective
  • Muscular
  • Nervous
• Epithelial tissues


  Cover animals and may be simple or stratified
• Types of epithelium based on shape


  • Squamous
  • Cuboidal
  • Columnar
• Simple squamous epithelium


  Consists of a single layer of flattened cells