Honors Biology Reading Guide Chapter 15 v Early conditions of earth Ø Atmosphere was probably thick with water vapor and from volcanic eruptions as

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1 Honors Biology Reading Guide Chapter 15 v Early conditions of earth Ø Atmosphere was probably thick with water vapor and from volcanic eruptions as well as nitrogen and its oxide carbon dioxide methane ammonia hydrogen and hydrogen sulfide Ø At first had intense heat from the core in a molten mass then as earth cooled water vapor condensed into oceans v Earliest evidence of life on earth Ø 3.5 billion year old fossils Ø Rocks called stromatolites were built upon ancient prokaryotes (could photosynthesize) v Four stages of life and how they evolved form non- living substances Ø The abiotic (non- living) synthesis of small organic molecules such as amino acids and nitrogenous bases Ø The joining of the small molecules into polymers such as proteins and nucleic acids Ø Packaging of these molecules into proto- cells membrane enclosed droplets that maintained an internal chemistry different from that of their surroundings Ø The origin of self replicating molecules that eventually made inheritance possible v What question did Miller and Urey want to answer in their experiment Ø If amino acids and other organic molecules could be formed under conditions though to stimulate those of early earth v What ingredients did they start their experiment with Ø Flask of warm water Ø Heat Ø Electrodes Ø Water vapor Ø Hydrogen gas Ø Methane Ø Ammonia Ø Sparks Ø Cold water v What elements of the experiment were meant to mimic the atmosphere of early earth Ø Flask of warm water sea Ø Electrodes lightning Ø Cold water atmosphere condense v What were the results of the experiment Ø Successful Ø Many organic molecules needs for life identified Ø Hydrocarbons and amino acids to make proteins v When these experiments were redone later on what were the results Ø Recent experiments using nitrogen and carbon dioxide have also produced organic molecules

2 Ø Mimic volcano conditions identify additional organic molecules that had been synthesized v Proto- cell Ø Membrane enclosed droplets that maintained an internal chemistry different from that of their surroundings v Ribozyme Ø An RNA molecule that functions as an enzyme v Why were these two substances important to the study of early life on earth Ø Form reproduce create maintain internal environment cause natural selection and mutations Ø Aided replication v What is RNA world Ø The hypothetical period in the evolution of life when RNA served as both rudimentary genes and catalytic molecules v What period did these major events occur in the geologic record Ø Age or reptiles Pennsylvanian Ø Age of mammals Jurassic Ø Oldest fossils of eukaryotes Proterozoic Ø Age of fish Cambrian Ø First tetrapod Devonian Ø Cambrian explosion Paleozoic v How many billion years ago Ø Origin of prokaryotes billion Ø Origin of single celled eukaryotes 2.1 billion Ø Origin of multicellular eukaryotes 1.5 billion Ø Colonization of land by plants 500 billion Ø Colonization of land by larger organisms 500 million v Radiometric dating Ø Decay of radioactive isotopes v Half- life Ø The time required for 50% of the isotope in a sample to decay v Method commonly used to date fossils Ø Carbon 14 for young fossils v Method that is commonly used to date rock layers Ø Potassium 40 v What is the principle of superposition Ø Any undisturbed sequence of rocks deposited in layers the youngest layer is on top and the older on bottom each layer being younger than the one below it and older then the one above it v Principle of cross- cutting relations

3 Ø The geographic feature which cuts another is the younger of the two features v What is the process of continental drift Ø Movements in the mantle causes the plates to move may be drifting apart sliding past each other or colliding v Consequence of living organisms Ø Altered habitats where organisms live Ø Extreme weather Ø Biological diversity reshaped Ø Extinction Ø New opportunities for organisms to survive v Ring of fire Ø Horseshoe around edges of pacific ocean Ø 90% of all earthquakes Ø 75% of all active volcanoes v What are the types of plates and their interactions Ø Continental and oceanic plates v Causes of mass extinctions Ø Global environmental changes were so rapid and disruptive that a majority of species was swept away in a short amount of time v Permian mass extinction Ø 96% of marine animals died Ø Tremendous toll terrestrial life Ø Enormous volcanic eruptions v Cretaceous mass extinction Ø Lost many species more than half of the marine species many terrestrial plants and animals as well Ø Dinosaurs die Ø Asteroid or comet iridium v Consequences of mass extinctions Ø Affect biological diversity Ø Remove large number of species Ø Can decimate thriving complex ecological community Ø Permanently remove advantaged species v Adaptive radiation Ø Periods of evolutionary change in which many new species evolve from common ancestor often following the colonization of new unexploited areas v How does adaptive radiation happen Ø Followed each mass extinction when survivors became adapted to many vacant ecological roles/niches in their communities v Homeotic genes Ø A master control gene that determines the identity of a body structure of a developing organism presumably by controlling the developmental fate of groups of cells v Four types of changes in developmental genes are important in a discussion of evolution

4 Ø How slight genetic changes can become magnified into major morphological differences between species Ø Genes that program development as organism develops from zygote to adult Ø Changes rate timing Ø Changes spatial pattern Ø New genes and changes in genes Ø Changes in gene regulation v Give some examples of homeotic genes being expressed differently in organisms Ø Change in rate/time Axotol salamander paedomorphosis retention adult body structures that were juvenile features in ancestral species gills Human chimp skulls more alike to fetus than adult Ø Change in spatial pattern Snakes from four limbed ancestor Ø New/change in genes Fruit fly has single cluster homeotic genes direct development major body part Ø Change in gene regulation Three stickleback fish Oceans and lakes less in the coast Spines reduced in lakes v How may evolutionary novelties arise Ø Can arise when structures that originally played one role gradually acquire a different one Ø Structures that evolve in one context but become opted for another function sometimes called exaptation s structure can become adopted to alternative functions structure not evolve in anticipation of future use v Explain evolutionary trends are not goal directed with horses Ø Horses start small more toes and eat shrubbery Ø Horses now large one toe grass eaters Ø Evolution was not directed in any way moving from start to finish Ø Yet an evolutionary trend does not imply that evolution is goal directed evolution is the result of interactions between organisms and the current environment if conditions change an apparent trend may cease or reverse itself v Homologous structure Ø Structures in different species that are similar because of common ancestry Ø Examples Arm of human and wing of a bat/bird v Analogous structures Ø Separate evolutionary organs but are superficially similar Ø Examples

5 Wing of bird/penguin v How are analogous structures related to the term convergent evolution Ø Can look alike despite not same if same environment and natural selection similar traits yet develop independent v Convergent evolution Ø The evolution of similar features in different evolutionary lineages when can result from living in very similar environments v Phylogeny Ø The evolutionary history of a species of group of related species v Where so we find the information on phylogeny Ø Fossil records Ø Morphological and molecular homologies among living organisms v Phylogenic tree Ø A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms v Cladistics Ø An approach to systematics in which common descent is the primary criterion used to classify organisms by placing them into groups called clades v Clades Ø A group of species that include an ancestral species and all of its descents v In- group Ø In cladistics study of evolutionary relationships the group of taxa whose evolutionary relationships are being determined v Out- group Ø In cladistics study taxon or group of taxa known to have diverged before the lineage that contains the group of species being studied v Parsimony Ø In scientific studies the each for the least complex explanation for an observed phenomenon v Evolutionary tree is hypothesis Ø Evidence is sued structural and developmental features molecular data behavioral traits only most likely hypothesis based on available evidence v Molecular biology Ø The study of molecular basis of genes and gene expression molecular genetics v Molecular clocks Ø Evolutionary timing method based on the observation that at least some regions genomes evolve at constant rates Ø Assumption estimates assume that the clocks have been constant for all that time and thus are highly uncertain v Tree of life Ø At first five kingdoms Monera, Protista, plantae, fungi, Animalia

6 Ø Now three domain system bacteria archaea eukarya kingdoms fungi plantae Animalia Ø Eukarya most closely related eukaryote than bacteria Ø First major split bacteria from other two domains then archaea and eukarya Ø Horizontal gene transfer genes transferred one genome to another through mechanisms