BIO lectures 9-11
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This 8 page Class Notes was uploaded by Avi Fox on Friday March 6, 2015. The Class Notes belongs to BIO 160 at University of Miami taught by Dana Krempels in Spring2015. Since its upload, it has received 45 views. For similar materials see EVOLUTION & BIODIVRSITY in Biology at University of Miami.
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Date Created: 03/06/15
Lecture 9 History of Life on Earth Biodiversity the diversity of living things on earth constantly changing Origin of life not really sure how 4 major phases Generation of small organic molecules from abiotic precursors The joining of these small subunits into macro proteins nucleic acids carbohydrates lipids The packaging of these macromolecules into protocells consisting of a membrane and an internal space filled with uid that was different from the surrounding medium Origin of selfreplicating molecules that made inheritance possible Abiogenesis Aleksandr Oparin first to suggest that chemical reactions in the primitive oceans hat could have created life Properties of life Anatomy Organized structure Metabolism Chemical reactions coordinated to perform vital functions Homeostasis Ability to maintain constant internal environment Internal and external Reaction to stimuli Growth and development Adaptability Ability to respond to environment changes Ability to reproduce Primordial Earth C02 water H2 N2 NH3 Hydrogen sulfide CO CH4 the last 6 are greenhouse gasses greenhouse gasses are necessary because they kept heat in the atmosphere Earths early atmosphere was reducing and conductive to formation of complex molecules Life on Earth could have also started in deepsea thermal vents or space debris colliding with earth Some say the early atmosphere was only weakly reducing or even neutral or rich in either CO2 or H2 Global Warming Joan Oro found sugars lipids thymine guanine adenine cytosine and uracil Experiments showed that dripping amino acid solutions onto hot clay or sand caused the amino acids to polymerize into oligopeptides short proteins RNA earliest genetic material Its easier to construct from raw materials has ribozymes enzymatic properties can modify its own structures as well as selfreplicate Extant viruses retroviruses demonstrate that RNA can be reverse transcribed into its more stable DNA Photosynthesis caused the earth to be oxidized Chlorophyll a blue greenish the most primitive form of chlorophyll that appeared 3 billion years ago is the early ancestors of prokaryotic cyanobacteria 1 billion years ago first eukaryotic autotrophs took 12 billion years for these autotrophs to produce enough oxygen that was taken up by exposed iron in earths crust rust once rust sink was filled 02 began to enter the atmosphere 600 mya atmospheric 02 was 1 of PAL cellular respirastion replaced fermentation ozone later started to form shielded microorganisms from lethal UV and Gamma radiation upper levels of the oceans could now be colonized by living things 400 mya land plants established 10 PAL Today the atmosphere is 21 Origin of Eukaryotes Autogeny extensive inpocketing of external plasma membrane formed a complex internal network of membranes Endosymbiosis Lynn Margulis autogeny began and then the cell took in an ancestral prokaryotic mitochondria that incorporated it into the cell Another event took place when a cell took in a photosynthetic prokaryote and that gave rise to the chlortrophs Evidence Giardia has energy transducing bacteria instead of mitochondria and 2 haploid nuclei The enzymes in mitochondrial chloroplast internal membranes are more similar to those of prokaryotes than they are to other enzymes found in eukaryotes They have circular chromosomes ribosome enzymes in the mitochondria and chloroplasts are more like those of prokaryotes than those of eukaryotes mitochondria and chloroplasts have their own genome separate from and largely independent of the nuclear genome mtDNA and chNA are circular and though there may be multiple copies all are genetically identical within a given cell hence these organelles arelike bacteria essentially haploid MtDNA and chNA circular chromosomes have no associated histones or RNA Cytochromes and other transport proteins used in mitochondria and chloroplasts are made in situ without cooperation from nuclear genome enzyme products Mitochondria and chloroplasts reproduce via binary fission very similar to that seen in prokaryotes Nucleus mitochondria and chloroplasts all have a double membrane Autotroph makes own food Heterotrophs eats others for food Sequential Endosymbiosis Primary endosymbiosis a larger cell engulfs a smaller cell which then takes up residence to benefit both cells Secondary endosymbiosis product of primary endosymbiosis is engulfed by a larger cell and then takes up residence to benefit both cells Have rise to a vast array of eukaryotic lineages Red algae products of primary endosymbiosis were ingested by heterotrophic eukaryotes and became the precursors of modern taxa dino agellates apicommplexans straminopiles Green algae Eugelnids chlorarachniphyta Horizontal Gene Transfer transfer of genes from one species to another by means other than traditional reproduction Carl Zimmer we are products of viral horizontal gene transfer Our genome is 6x more virus than genes Geology and the Fossil Record Relative dating understanding that deeper strata are older Animals with hard body parts make the best fossils Can only date in a relative time scale of existence compared with other fossils Absolute radiometric dating molecules usually exist in a stable form However some of them are Isotopes that want to decay Radioactive isotope is one with an unstable nucleus To become stable it emits ionizing radiation in the form of alpha beta and game rays C14C12 1 11013 remains constant while they are alive Once they die the C14 goes back to stable nitrogen Half life of C14 5730 years the more decay product to radioactive isotope the older the sample Biogeography the distribution and diversity of living things over time How life moved over the earth over time Organisms that are found all over the earth is more likely to have evolved when the continents were together Mountain and island formations Subduction zone area where one plate is being forced underneath the edge of another one Form deep trenches Sea oor spreading zone area where volcanic activity causes the ocean oor to split and spread apart Climate change and continental drift climate changed as the continents moved because climate is governed by its annual exposure to sunlight Tropics tropic of Caner north235 N tropic of Capricorn south 235 S receive the highest annual input of solar energy on earth Only place on earth where the sun shines directly overhead 0 the equinoxes march 21 September 21 Subtropics between the tropics and 30 degrees N and S Florida Temperate region 3060Degress Polar region lies above 60N artic and S Antarctic Earths 235 tilt of the axis is why we have annual changes in solar irradiation and that creates the seasons in both hemispheres The different seasons created the diverse organisms because each continent was subjected to different pressures Gradual change in climate of the moving continents was a major driving force for speciation and extinction Continental drift caused allopatric speciation on a large scale Cambrian Explosion 540 million years ago the fossil record reveal a sudden appearance of a vast array of different types of organisms All living phyla evolved by the end of the Cambrian explosion Extinction can be driven by species interactions climate change glaciation changes in seal level changes in ecosystems at a local level habitat loss changes in river patterns Species interactions Symbiosis refers to the member of 2 species having some sort of ecological interactions that affects both populations Coevolution 2 species evolve in response to each other s activities Obligate mutualism neither organism can survive without the other Termites need their intestinal agellate to survive Flowering plants and insect pollinators need one another without them they would die Photocooperation both parties benefit but it isn t necessary for survival The clown fish gets protection from the Sea Anemone and the clown fish feeds the anemone and protects it from predators Competition both parties compete for the same resources and therefore both parties are at a loss until one organism goes extinct or they learn to use resource partitioning Neutralism the populations don t help each other or oppose one another Doesn t really happen in nature because all organisms in an ecosystem are interconnected Predation the predator kills the prey so one benefits at the expense of the prey Driven evolution to create such phenomena such as crypsis camo ou age aposematism warning coloration and mimicry to avoid predators Batesian Mimicry harmless mimic to look like a toxic model Mullerian Mimicry several poisonous species resemble one another A predator only has to try on species to avoid all of them Poionous toxic when eaten or touched Venomous delivers toxin with an apparatus such as a fang or stinger Parasitism a parasite feeds on the host s body without killing it outright Definitive host a host to an adult parasite Intermediate host a host to juvenile parasite The definitive host is usually a predator of the intermediate host and the life cycle is completed when the definitive host eats the intermediate host freeing the larval forms to take up residence Parasitoidism a parasitoid acts a parasite until some point in its life cycle at which point it kills the host Commensalism one species benefits from the presence of another but doesn t effect the other species Egrets follow grazers that cause stir up the insects The Egrets benefit from the presence of the grazers Ammensalism one species impedes the success of another species but is neither positively nor negatively affected Allelopathy some plants produce toxic compounds that inhibit the growth of other plants Penicillin inhibits the growth of many species of bacteria Not completion because the other organism stands no chance Mass Extinctions 5 mass extinctions 6th happening now due to humans Permian Mass Extinction over 500000 years very little time 96 of all marine animals died off Many terrestrial animals also suffered massive extinctions Happened in line with huge volcanic eruptions in Siberia This is due to direct effects of lave and ash excess C02 caused global temperature to rise 6 degrees F more uniform temperature across the globe reduced ocean cycling reducing oxygen content ocean anoxia anaerobic bacterial overgrowth in oceans could have increases H2S concentrations that are toxic and destroys the ozone Cretaceous Mass Extinction more than half of all marine species and huge number of terrestrial species died off Dinosaurs died off thought to be caused by the Chixulub comet the crater lies at the bottom of the ocean in the Yucatan peninsula The great Oxygenation eventcatastrophe cyanobacteria began releasing oxygen into the atmosphere killing most of the anaerobes It also caused red rust FeO to fall onto the ocean oor Life began to diversify once the atmosphere began to become oxygenated Needed organisms that produced C02 to perform photosynthesis Lecture 10 Phylogeny Taxa evolutionary related group Character traits morphological physiological biochemical molecular Character state specific value of particular character Plesiomorphic primitive symplesiomorphies shared primitive characters Apomorphic derived synapomorphies Homoplasy analogous character not a homology Phylogeny evolutionary history of a species can be represented by a phylogenetic tree Node each branch point represents common ancestor 3 domains of life Eukaryota Bacteria Archaea Carl Woese created the 3 domains based on the nucleotide sequence of different type of RNA rRNA Ribosomal RNA all living things have it it performs essentially the same function in everything tends to be stable and doesn t get many mutations can be compared across taxa to see where changes have occurred Outgroups Why Classify 1 Aid to memory don t have to remember characteristics of individual members only need to know the group 2 Aid to prediction you can predict that a new organism that falls into a group you can look for shared characteristics 3 Way to explain evolutionary relationships 4 Provide a stable relatively unchanging system of internationally recognizable names Taxonomy Carl von Linne Systema naturaecreated way to name organisms based off shared characters called the Linnaean system Father of modern taxonomy Species grouped in genus grouped in family Domain Kingdom phylum class order family genus species Abbreviations first time writing it have to write it out then you can write a capital first letter Genus and spell out the species Mentioning the same genus multiple times can represent the G Eleutheros 3 Dactyl toes Plani at Rostris nose Need to Latinize names Taxonomy Taxon names 1 Taxons name 2 Taxons rank rankles system only described by its name 3 Taxons content who s in it Classification ordering of organisms into groups based on their relationships Alpha taxonomy describing and naming of species Beta taxonomy arranging species into a system of higher classification Gamma taxonomy study of the biological aspects of species Basic rules of biological nomenclature no 2 species within one taxa can have the same ending species and genus name must be the same gender Masculine US feminine a must be latin or latinized Whichever was named first gets the name The family is named after the first one named Practical reasons for nomenclature Malaria outbreak in Europe had to gure out different sibling species and were able to eradicate it Envolopes with anthrax bacteria spores were looked at in a phylogenetic trees and they were able to identify where it was coming from Systematics Outgroup used to determine which characters are primitive and derived If its found in both ingroup and outgroup it is considered primitive Lecture 11 First organisms Prokaryote before the nut no nucleus Eukaryote true nut has a nucleus Prokaryotes are in 2 Domains Domain Archaea the archaebacteria our closer relative thought to have come from the extremophiles Domain Bacteria true bacteria Eukarya and archae share a more common ancestor Earliest known fossils are closely related to archaebacteria Have no membrane bound organelles no nucleus But have internal membrane systems Domain Archae Nature s extremophiles Domain includes organisms that can withstand the most extreme environments of any living thing known Not based on common descent but placed into form taxa lump together because they have a similarity that re ects their metabolic strategies Doesn t represent physiological homologies Methanogens create methane releases the green house gas Thermophiles living in extremely hot environment like deepsea thermal vents sulfur hot springs Ribosomal RNA shows we are most related to the deepsea thermophiles Halophiles Achaeans living in extremely salty environment Archaeane Morphology DNA is single circular chromosome with single copy of genes haploid Genome size ranges from 500000 6million base pairs Some are shaped similar to bacteria spherical and rode shaped Cell wall is made of material unique to archaeas Flagella are composed of multiple proteins Flagellins Encoded by several genes unique to archaens tRNA s are unique Arechaen ribosomes are more similar to those of eukaryotes than to those of bacteria Cell membrane structure and composition unique to Archaeans Domain Bacteria true bacteria Beta taxonomy taxonomy concerned with arranging species into higher and lower taxa may never know true evolutionary relationships Structure and Function may be unicellular aggregateclumped together or colonialcooperation haploid 1000 genes more derived species amy form colonies with fivision of labor among cells May be categorized on the basis of shape shapes don t necessarily re ect phlyognetic relationships there can be convergence and adiversity of shapes in closely related bacteria Cocci round Bacilli Rod shaped Spirillae and spirochaetes helix Prefix staphyl clusters and strept bent Bacteria range in size from 15 micrometers consists of a single circular chromosome of double stranded DNA organized in the nucleoid region of the cell Plasmids small circular pieces of autonomously replicating DNA A plasmid usually contains only a few genes and isn t considered part of the bacterium s genome But it may give phenotypic traits like antibiotic resistance or the ability to produce toxins Salmonella and clostridium
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