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Life on Earth (Chapter 25 The History of Life on Earth (Scientist and…

- - - - There are 20 amino acids
      - Nitrogenous Bases
        
        Uracil
        
        Adenine
        
        Thymine
        
        Cytosine
        
        Guanine
    - - protocells are the first cells that ever existed, these cells must be able to carry out reproduction and energy processing
        
        metabolism provides an abundant supply of nucleotide building blocks and enzymatic machinery
        
        vesicles
        
        fluid-filled compartments enclosed by a membrane-like structure
        
        can maintain a chemical environment from that of their surroundings
        
        can form spontaneously when lipids or other organic molecules are added to water
        
        molecules that have both a hydrophobic region and a hydrophillicregion can organize into a bi layer similar to the lipid bi layer of a plasma membrane
        
        formed when soft clay produced by volcanic ashes allows the molecules to react
        
        have a selectively permeable bi layer and can perform metabolic reactions using an external source of reagents
        
        If vesicles could grow and split, it can pass its RNA molecules to its "daughter" cells and then the "daughter" cells would become protocells
        
        Self-Replicating of RNA
        
        RNA plays a central role in protein synthesis and can also function as an enzyme-like catalyst
        
        1 more item...
        
        RNA molecules were able to replicate and store genetic information about the vesicles that carry them
        
        1 more item...
  - - - the planet formed from vast cloud of dust and rocks that surrounded the young sun
      - The Massive Bombardment
        
        huge chunks of rocks and ice left over from the formation of the solar system
        
        the collisions generated a lot of heat that all the available water vaporized
        
        prevented the formation of seas and lakes
        
        The atmosphere had little oxygen and was thick with water vapor released by volcanic eruptions , as earth cooled, the water vapors condensed into ocean and hydrogen escaped into space
        
        some evidence suggest that earth's atmosphere was made primarily of nitrogen and carbon dioxide
    - - areas on the seafloor where heated water and minerals gush from Earth's interior into the ocean
        
        Some vents "black smokers" release water so hot (3oo C-400C) that organic compounds formed there are unstable
        
        Alkaline vents
        
        release water with high pH levels and is warm (40-90) rather than hot
        
        a more suitable environment for the origin of life
  - - - shows there have been changes in the kinds of organisms on Earth at different points in time
    - - the fossil record is based primarily on the sequence in which fossils have accumulated in sedimentary rock layers
        
        strata
        
        tells us the sequence in which the fossils were laid down and their relative age
        
        Radiometric Dating
        
        based on the decay of of radioactive isotopes
        
        a "radioactive parent" isotope decays to a daughter isotope at a characteristic rate.
        
        the rate of decay is expressed by the half-life, the time required for 50% of the parent isotope to decay
        
        fossils contain isotopes of elements that accumulated in the organisms when they are alive
        
        For example,a living organism contains the most common carbon isotope, carbon-12, as well as a radioactive isotope, carbon-14
        
        when the organism die, the amount of carbon-12 does not change, but carbon-14 starts to decay
        
        strata does not tell their actual age
    - - Many of Earth's organisms did not die in the right place and time to be preserved as fossils
      - of the fossils that were formed were later destroyed by geological processes and only a fraction of others were discovered
      - The known fossil record is biased in favor of species that existed for a long time, were abundant and widespread in certain kinds of environments
  - - - a standard time scale that divides Earth's History into four eons and further subdivisions
        
        Archaean
        
        Concentration of atmospheric oxygen begins to increase
        
        oldest fossils of cells (prokaryotes) appear
        
        Oldest known rocks on Earth's surface
        
        Proterozoic
        
        Neo-proterozoic
        
        Ecidacaran
        
        Diverse algae and soft-bodied invertebrate animals appear
        
        Hadean
        
        approximately 4.6 million years ago
        
        Origin of Earth
        
        Phanerozoic
        
        Cenozoic
        
        Neogene
        
        Pilocene
        
        Appearance of bipedal human ancestors
        
        Milocene
        
        Continued radiation of mammals and angiosperms, earliest direct human ancestors
        
        Quaternary
        
        Pleistocene
        
        Ice ages, origin of genus Homo
        
        Holocene
        
        Historical Time
        
        Paleogene
        
        Oligocene
        
        Origins of many primate groups
        
        Eocene
        
        Angiosperm dominance increases, continued radiation of most present-day mammalian orders
        
        Paleocene
        
        Major radiation of mammal,birds, and pollinating insects
        
        Mesozoic
        
        Cretaceous
        
        Flowering plants (angiosperms) appear and diversity; many groups of organisms, including most dinosaurs, become extinct at end of period
        
        Jurassic
        
        Gymnosperms continue as dominant plants; dinosaurs, abundant and diverse
        
        Triassic
        
        Cone-bearing plants (gymnosperms) dominate landscape; dinosaurs evolve and radiate, origin of mammals
        
        Paleozoic
        
        Permian
        
        Radiation of reptiles, origin of most present-day groups of insects, extinction of many marine and terrestrial organisms at end of period
        
        Carboniferous
        
        Extensive forests of vascular plants form; first seed plants appear, origin of reptiles, amphibians dominant
        
        Devonian
        
        Diversification of bony fishes; first tetrapods and insects appear
        
        Silurian
        
        Diversification of early vascular plants
        
        Ordovian
        
        Marine algae abundant; colonization of land by diverse fungi, plants, and animals
        
        Cambrian
        
        Sudden increase in diversity of many animal phyla (Cambrian explosion)
  - - - free O2 dissolved in the surrounding water until it had a high concentration to react with iron
        
        Iron oxide is produced and is a precipitate
        
        "caused to be deposited in solid form from a solution
        
        Additional O2 dissolved in the water until bodies of water become saturated with oxygen
        
        Oxygen "gas out" into atmosphere
        
        This killed some of the prokaryotic because of the enzymes
    - - Endosymbiosis
        
        when a prokaryotic cell engulf a small cell that would evolve into an organelle found in all eukaryotes , the mitochondrion
        
        serial symbiosis
        
        supposes that mitochondria evolved before plastids through a sequence of symbiotic events
        
        mitochondria and plastids are thought to have descended from bacterial cells
        
        The inner membrane s of both organelles have enzymes and transport systems that are homologous to those found in the plasma membranes of living bacteria
        
        Mitochondria and plastids replicate by splitting process similar to that of bacteria
        
        mitochondria and plastids have cellular machinery needed to transcribe and translate their DNA into proteins
        
        mitochondria and plastids are more similar to bacterial ribosomes than they are to the cytoplasmic ribosomes of eukaryotic cells
      - Multicellularity Eukaryotes
        
        the oldest known fossils of multicellular eukaryotes are the small red algae that lived 1.2 billion years ago
- - - - can be reconstructed using systematics
        
        a discipline focused on classifying organisms and determining their evolutionary relationships
      - taxonomy
        
        naming and classifying organisms
        
        Binomial Nomenclature
        
        binomial
        
        two-part format of the scientific name
        
        the second part, called the specific epithet is unique for each species within the genus
        
        the first part of the binomial is the name of genus (plural, genera) to which the species belong
        
        Example : Panthera paradus
        
        the scientific name for the leopard
        
        first letter of genus is capitalized
        
        the entire binomial is italicized
    - - Hierarchy of increasingly inclusive categories
      - the taxonomic system named after Linnaeus, the Linnaean system places related genera in the same family
        
        families into orders
        
        orders into classes
        
        classes into phyla
        
        phyla into kingdoms
        
        kingdoms into domains
        
        the named taxonomic unit at any level of the hierarchy is called a taxon
    - - the evolutionary history of a group of organisms can be represented in a branching diagram
      - represents a hypothesis about evolutionary relationships
        
        relationships are depicted as a series of dichotomies, or two-way branch points
        
        branch points
        
        represents the common ancestor of the two evolutionary lineages diverging from it
        
        Example: chimpanzees and humans are considered sister taxes
        
        groups of organisms that share an immediate common ancestor that is not shared by any other group
        
        members of a sister group are closest relatives
      - the tree is rooted, meaning that a branch point within the tree represents the most recent common ancestor of all taxa in the tree
      - basal taxon
        
        a lineage that diverges from all other members of its group early in the history of the group
      - intended to show patterns of descent, not phenotypic similarity
      - we cannot infer the ages of the taxa or branch points shown in a tree
      - infer species identities by analyzing the relatedness of DNA sequences from different organisms
  - - - phenotypic and genetic similarities due to shared ancestry
      - Morphological Homolgy
        
        organisms that share very similar morphologies or similar DNA sequences are likely to be more closely related to other organisms with vastly different structure or DNA sequence
    - - analogy
        
        rather than a shared ancestry, similarity is caused by convergent evolution
        
        convergent evolution
        
        occurs when similar environmental pressures and natural selection produce similar adaptations in organisms from different lineages
      - the more elements that are similar in two complex structures, the more likely it is that the structures evolved from a common ancestor
      - if genes in two organisms share many portions of their nucleotide sequences, it is likely that the genes are homologous
        
        Horizontal gene transfer
        
        a process in which genes are transferred from one genome to another through mechanisms such as exchange of transposable elements and plasmids
  - - - Shared ancestral character
        
        a character that originated in an ancestor of the taxon
    - - each includes an ancestral species and all of its descendants
      - are nested within larger clades
      - Monophyletic Group
        
        consists of an ancestral species and all its descendants
      - Paraphyletic group
        
        consists of an ancestral species and some of its descendants
        
        the most common ancestor of all members of the group is part of the group
      - Polyphyletic Group
        
        group that includes distantly related species but does not include their most common ancestor
        
        the most recent common ancestor is not part of the group
    - - an evolutionary novelty unique to a clade
      - outgroup
        
        a species or group of species from an evolutionary lineage that is closely related to but not part of the group of species that we are studying
        
        in groups
        
        Example: the lancelet
        
        a small animal that lives in mudflats and is a member of the more inclusive group called the chordates
        
        unlike the veterbrates, the lancelet does not have a backbone
  - - - as a result,molecular trees can represent short or long periods of time, depending on which genes are used
        
        Gene duplication and gene families
        
        gene duplicatiion increases the number of genes in a genome
        
        gene families are groups related genes within an organism's genome
        
        homologous genes
        
        Orthologous Genes
        
        the homology is the result of a speciation event and hence occurs between genes found in different species
        
        Paralogous genes
        
        the homology results from gene duplication, hence multiple copies of these genes have diverged from one another within a species
      - Example; the DNA that codes for ribosomal RNA changes relatively slowly
        
        studies have shown that fungi is more closely related to animals then to plants
      - Gene Evolution
- - - - new defensive adaptations appeared in their prey
  - - - Example: land plants today have a vascular system for transporting materials internally and a waterproof coating of wax on their leaves that slows the loss of water
      - plants appear to have colonized land with fungi, that aids in absorption of water and minerals from the soil
  - - - movement in mantle causes plates to move in a process called continental drift
        
        continental drift promotes allopatric speciation
        
        alters the habitats in which organisms live
        
        separated the super continent
        
        Pangaea
        
        experienced drastic climate changes
        
        locations shifted
  - - - determines where certain structures appear in the organism's body
    - - a species may retain body features that were juvenile structures to an ancestral species
    - - an evolutionary change in the rate or timing of developmental events