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General BiologyI Answers to FAQ • • • • • • Professor Garcia or Roman. Exam material is based on powerpoint presentation. There will be 50 multiple choice exam questions. Each lecture will be weighed equally on exam. Makeup exams will be far more difficult. If you cannot make it to my office hours make appointment with me after a lecture. • If average exam grades are very bad they will be adjusted...Expect the average to be no better than a “C” if there is a grade adjustment. • Due to time constraints may not always be able to field questions...please come to office hours. • Study advice...Have all chapters read for the week for all your classes come Monday or Tuesday. Learn memory techniques. Web-assisted Course webct.fiu.edu Panther ID and Birthday (if you don’t have account) Classroom Text book = Biology by Raven 8th edition. Laboratory Information Labs are held this week You need: A lab book (Biology Vodopich) Safety glasses Lab coat The Tree of Life Chapter 26 Origins of Life The Earth formed as a hot mass of molten rock about 4.5 billion years ago (BYA) -As it cooled, chemically-rich oceans were formed from water condensation Life arose spontaneously from these early waters (@ about 49-88 Celsius) Or life may have infected Earth from some other planet (via meteors or cosmic dust) -This hypothesis is termed Panspermia 5 Fundamental Properties of Life Cellular organization Paramecia (protists) Sensitivity “eating” yeast Growth Development Reproduction Regulation Homeostasis Heredity 6 Environmental Conditions on Early Earth Earth’s Early atmosphere had CO2, N2, H2O and H2 Carbon-Rich Reducing atmosphere...energetically easier to form carbon-rich molecules 7 First Organisms May have been born in Earth’s crust, in clay, or at deep-sea vents 3.5BYA We have Oldest fossils of prokaryotes. 2.5-2BYA Cyanobacteria...Appearance of oxygen in atmosphere 1.5BYA Oldest definite fossils of eukaryotes 8 Miller-Urey Experiment (1953) Reproduced Earth’s early atmosphere Prebiotic Chemistry 9 Evolution of Cells *Self replicating RNA may have been first genetic material *Amino acids polymerized into proteins *Metabolic pathways emerged *Lipid bubbles became living cells with cell membranes-CONCENTRATED MOLECULES *Several innovations contributed to diversity of life -Eukaryotic cells -Sexual reproduction -Multicellularity 10 Classification of Organisms More than 2000 years ago, Aristotle divided living things into animals and plants Greeks and Romans later grouped plants and animals to basic units called genera Felis (cats) and Equus (horses) In the 1750s, Carolus Linnaeus instituted the use of two-part names, or binomials -Homo sapiens (Genus and Species name) 11 Classification of Organisms Taxonomy is the science of classifying living things *A classification or organization is called a taxon *Scientific names avoid confusion caused by common names 12 The Linnaean Hierarchy Taxa are based on shared characteristics -Domain (most inclusive) -Kingdom -Phylum -Class -Order -Family -Genus -Species (least inclusive) 13 Hierarchical System Eukaryotic Cells Heterotrophs w/ no cell wall Notocord Vertebrates Mammary Glands Gnawing teeth 4 front toes 5 back toes Arboreal Morphological Differences 14 Chapter 23 Linnaean Hierarchy may represent Convergent Evolution and NOT COMMON ANCESTRY...(this is relative to a hypothesized recent ancestor) Everybody in the shown animal group has an ancestral trait from this animal here Some in the shown animal group have a derived trait from this animal here We would have a polyphyletic group if we said all the animals in this group Descended from here Limitations of the Hierarchy Hierarchies are being re-examined based on molecular analysis Do not accurately correspond to evolutionary relationships amongst animals Hiearchies may suggest 2 animals came from the same predecessor (monophyletic) but in fact don’t (polyphyletic). Linnaean ranks (listed in the hierarchy) do not give strict inheritance information of the members in a rank 18 Grouping Organisms Biologists are increasingly adopting a threedomain phylogeny based on rRNA studies -Domain Archaea -Domain Bacteria -Domain Eukarya Each of these domains forms a clade Archaea and Eukarya are more closely related to each other than to bacteria 19 Grouping Organisms Carl Woese proposed a six-kingdom system Prokaryotes Eukaryotes 21 Grouping Organisms via Molecular Analysis • Since all life has genetic material in common we can group each life form according to differences and similarities in genetic material. • The sequenced genetic material is usually rRNA. • Two organisms that inherit similar rRNA sequence are closer related than two organisms with a dissimilar sequence--NO MATTER HOW THEY LOOK LIKE. 22 Phylogeny prepared from rRNA analyses. During evolution, microbes swapped genetic information via horizontal gene transfer (HGT) 23 Bacteria *Most abundant organisms on Earth...more in your mouth than mammals on Earth *Extract nitrogen from the air, and recycle carbon and sulfur *Perform much of the world’s photosynthesis *Responsible for many diseases *Make up our natural intestinal flora *Most taxonomists recognize 12-15 different groups 24 Archaea Prokaryotes that are more closely related to eukaryotes Characteristics -Cell walls lack peptidoglycan -Membrane lipids are branched -Distinct rRNA sequences Divided into three main groups 25 Methanogens -Use H2 to reduce CO2 to CH4 -Strict anaerobes that live in swamps Extremophiles -Thermophiles – High temperatures -Halophiles – High salt -Acidophiles – Low pH Nonextreme archaea -Grow in same environments as bacteria -Nanoarchaeum equitans – Smallest cellular 26 genome 27 Eukarya Prokaryotes ruled the earth for at least one billion years Eukaryotes appeared about 2.5 BYA Their structure and function allowed multicellular life to evolve Eukaryotes have a complex cell organization -Extensive endomembrane system divides the cell into functional compartments 28 Mitochondria and chloroplasts most likely gained entry by endosymbiosis -Mitochondria were derived from purple nonsulfur bacteria -Chloroplasts from cyanobacteria 29 The Four Eukaryotic Kingdoms Protista -Unicellular with few multicellular organisms -Not monophyletic Fungi Plantae Animalia -Largely multicellular organisms -Each is a distinct evolutionary line derived from a unicellular protist 30 Symbiotic Events 31 Key Eukaryotic Characteristics Compartmentalization -Allows for increased subcellular specialization Multicellularity -Allows for differentiation of cells into tissues Sexual reproduction -Allows for greater genetic diversity 32 33 34 Making Sense of the Protists Protists are a paraphyletic group -Catchall for eukaryotes that are not plant, fungus or animal Divided into six groups -However, at least 60 protists do not fit into any of these groups 35 Notice that Protists (olive green color) are not monophyletic A new kingdom, Viridiplantae, has been suggested 36 -Plants + green algae(Chlorophyta) Origin of Plants 37 Green alga consist of 2 monophyletic groups Chlorophyta and Streptophyta Streptophyta has 7 clades, including land plants Sister clades Land plants arose from an ancestral green38alga, and only once during evolution Some land plants show evidence of horizontal gene transfer The flowering plant Amborella acquired three moss genes Close contact increases the probability of HGT 39 Modeling evolutionary relationships provides... An orderly and logical way to name organisms Insights in understanding the history of major features and functions--Gather clues about the genes involved in speciation and trait formation 40 Segmentation is regulated by the Hox gene family Segmentation has been used in the past to group arthropods and annelids close together rRNA sequences now suggest they’re distantly related 41