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War On Words: NYC Dept. Of Education Wants 50 ‘Forbidden’ Words Banned From Standardized Tests Words that suggest wealth are excluded because they could make kids jealous. “Poverty” is also on the forbidden list. That’s something Sy Fliegal with the Center for Educational Innovation calls ridiculous. “The Petersons take a vacation for five days in their Mercedes … so what? You think our kids are going to be offended because they don’t have a Mercedes? You think our kids are going to say ‘I’m offended; how could they ask me a question about a Mercedes? I don’t have a Mercedes!’” Fliegal said. Here is the complete list of words that could be banned: Abuse (physical, sexual, emotional, or psychological), Alcohol (beer and liquor), tobacco, or drugs, Birthday celebrations (and birthdays) Cancer (and other diseases) Catastrophes/disasters (tsunamis and hurricanes), Children dealing with serious issues, Cigarettes (and other smoking paraphernalia) Crime Death and disease, Divorce, Evolution, Expensive gifts, vacations, and prizes, Halloween, Homelessness, Homes with swimming pools, Hunting Junk food, Loss of employment, Nuclear weapons, Occult topics (i.e. fortune-telling), Politics, Pornography, Poverty, Religion Religious holidays and festivals (including but not limited to Christmas, Yom Kippur, and Ramadan) Running away, Sex, Slavery, Terrorism, Violence, War and bloodshed, Weapons (guns, knives, etc.), Witchcraft, sorcery, etc. © Cengage Learning 2015 Biology Concepts and Applications | 9e Starr | Evers | Starr Chapter 18 Life’s Origin and Early Evolution © Cengage Learning 2015 © Cengage Learning 2015 Which of these groups are more closely related? a) jellyfish, starfish, swordfish b) human, cat, manatee © Cengage Learning 2015 18.1 What Was The Building Material For Earth’s First Life? • Conditions on early Earth – Earth formed about 4.6 billion years ago – Early atmosphere contained little or no oxygen – Presence of water – Volcanic eruptions were common – Constant hail of meteorites © Cengage Learning 2015 What Was The Building Material For Earth’s First Life? • Formation of simple organic compounds – All life consists of: • Amino acids • Fatty acids • Nucleotides • Simple sugars © Cengage Learning 2015 What Was The Building Material For Earth’s First Life? • Where did the subunits of the first life come from? • There are several possibilities: – Lightning-fueled atmospheric reactions – Reactions at deep-sea hydrothermal vents – Meteorites from space © Cengage Learning 2015 What Was The Building Material For Earth’s First Life? • Hydrothermal vents – Deep underwater openings in ocean where mineral-rich water heated by geothermal energy streams out • Reactions in the hot, mineral-rich water near deepsea hydrothermal vents also produce organic building blocks • Simulated experiments combining hot water with carbon monoxide (CO), potassium cyanide (KCN), and metal ions formed amino acids © Cengage Learning 2015 What Was The Building Material For Earth’s First Life? • Miller-Urey experiment – 1953, Stanley Miller and Harold Urey showed that reactions in Earth’s early atmosphere could have produced building blocks for the first life – Indirect evidence that organic compounds self-assemble spontaneously under conditions like those in Earth’s early atmosphere © Cengage Learning 2015 “Atmosphere” CH4 Water vapor NH3 H2 Electrode Condenser Cold water Cooled water containing organic molecules H2O Stanley Miller re-creating his 1953 experiment Abiogenesis © Cengage Learning 2015 “Sea” Sample for chemical analysis Miller and Urey’s experiment Figure 15.4 A C5H5N5 G T C © Cengage Learning 2015 18.2 What Steps Led to the Formation of the First Cells? • Similarities in structure, metabolism, and replication among all life indicate descent from a common cellular ancestor – Experiments demonstrate how traits and processes seen in all living cells could have begun with physical and chemical reactions among non-living collections of molecules © Cengage Learning 2015 Precambrian Common ancestor to all present-day life Origin of Earth 4,500 © Cengage Learning 2015 Earth cool enough for crust to solidify 4,000 Oldest prokaryotic fossils 3,500 Millions of years ago 3,000 Atmospheric oxygen begins to appear due to photosynthetic prokaryotes 2,500 Figure 15.1a What Steps Led to the Formation of the First Cells? • Origin of metabolism – Proteins that speed metabolic reactions might have first formed when amino acids stuck to clay, then bonded under the heat of the sun – Metabolism may have begun in rocks near deep-sea hydrothermal vents when iron sulfide in the rocks donated electrons to dissolved carbon monoxide © Cengage Learning 2015 What Steps Led to the Formation of the First Cells? • Protocells – May have preceded cells – Membrane-like structures and vesicles form when proteins or lipids are mixed with water – Membranous sacs that contain interacting organic molecules; hypothesized to have formed prior to the earliest life forms – Origin of the cell membrane © Cengage Learning 2015 18.3 What Do We Know About Early Cells? • Early divergence separated bacteria from ancestors of archaeans and eukaryotes – An oxygen-releasing, noncyclic pathway of photosynthesis evolved in one bacterial lineage, cyanobacteria – 2.5 billion years ago, oxygen released by cyanobacteria began to accumulate in Earth’s sea and air – Cyanobacteria changed Earth’s atmosphere © Cengage Learning 2015 18.4 How Did Increasing Oxygen Affect Early Life? • Evidence of early eukaryotes – Biomarker • Molecule produced only by a specific type of cell • A molecular signature – Oldest widely accepted eukaryote microfossils date to about 1.8 billion years ago © Cengage Learning 2015 1 Billion • How many millions make a Billion? • If a volcano erupts every 1,000 years, how many times will it erupt in a million years? • If a volcano erupts every 1,000 years, how many times will it erupt in a billion years • How old will you be when you get to your Billionth second in life? • 1,000,000,000 60 seconds per minute X 60 minutes per hour X 24 hours in a day X 356.25 days per year = 31.68 years © Cengage Learning 2015 How Did Increasing Oxygen Affect Early Life? • Effects of increasing oxygen – Interferes with self-assembly of complex organic compounds – Prevented evolution of new life from non-living molecules – Presence of oxygen gave organisms that thrived in aerobic conditions an advantage – Formation of an ozone layer in the upper atmosphere protected Earth’s surface from high levels of solar ultraviolet (UV) radiation © Cengage Learning 2015 18.5 How Did Eukaryotic Organelles Arise? • Scientists study modern cells to test hypotheses about how organelles evolved in the past – By one hypothesis, internal membranes typical of eukaryotic cells may have evolved through infoldings of plasma membrane of prokaryotic ancestors – Existence of some bacteria with internal membranes supports this hypothesis © Cengage Learning 2015 How Did Eukaryotic Organelles Arise? • Origin of mitochondria and chloroplasts – Endosymbiont hypothesis • Mitochondria and chloroplasts resemble bacteria • One species lives and reproduces inside another • Over generations, host and guest cells come to depend upon one another for essential metabolic processes © Cengage Learning 2015 Plasma membrane Photosynthetic prokaryote DNA Cytoplasm Membrane infolding (Some cells) Endosymbiosis Endoplasmic reticulum Nucleus Ancestral prokaryote Aerobic heterotrophic prokaryote Chloroplast Mitochondrion Nuclear envelope Photosynthetic eukaryotic cell Cell with nucleus and endomembrane system (a) Origin of the endomembrane system © Cengage Learning 2015 (b) Origin of mitochondria and chloroplasts Figure 15.20 18.6 What Happened During the Precambrian? • Precambrian – Encompasses almost all of Earth’s history – From 4.6 billion years ago to Cambrian (542 mya) – Life arose and diversified – By the close of this period, bacteria, archaea, and eukaryotes lived in the sea © Cengage Learning 2015 18.7 Life in Extreme Habitats • Astrobiologists study properties of the ancient Earth that allowed life to arise, survive, and diversify – Astrobiology • The scientific study of life’s origin and distribution in the universe • Presence of cells in deserts and deep below Earth’s surface suggests life may exist in similar settings on other planets © Cengage Learning 2015 Biology Concepts and Applications | 9e Starr | Evers | Starr Chapter 19 Viruses, Bacteria, and Archaea © Cengage Learning 2015 © Cengage Learning 2015 19.1 What Are Viruses? • Viruses: noncellular infectious agents – Consists of a protein coat around a core of DNA or RNA • The coat is enveloped in a bit of plasma membrane derived from a previous host – Replicates only in a host cell – A virus is far smaller than any cell – Has no ribosomes or other metabolic machinery © Cengage Learning 2015 19.2 How Do Viruses Affect Human Health? • Viral diseases – Pathogens: disease-causing agents – Usually produce mild symptoms persist in body for long periods – Can be latent and then reawaken © Cengage Learning 2015 How Do Viruses Affect Human Health? • Common viral diseases – Nonenveloped viruses: • Adenoviruses (colds) • Viral gastroenteritis (stomach flu) • Human papillomavirus (genital warts, cervical cancer) © Cengage Learning 2015 How Do Viruses Affect Human Health? • Enveloped viruses – Herpes viruses (cold sores, genital herpes, infectious mononucleosis, chicken pox) – Influenza (flu) – Mumps, measles, and German measles © Cengage Learning 2015 How Do Viruses Affect Human Health? • Emerging viral diseases – Changes to viral genomes as a result of mutation or gene exchanges can alter the properties of a viral disease – A disease that was previously unknown, is new to humans, or has recently begun spreading to a new region © Cengage Learning 2015 How Do Viruses Affect Human Health? • West nile fever – An enveloped RNA virus that replicates in birds – Mosquitoes carry the virus from host to host (the vector for this virus) – Attacks the nervous system and can be fatal – An endemic disease throughout the continental United States © Cengage Learning 2015 How Do Viruses Affect Human Health? • Ebola hemorrhagic fever – Ebola virus is highly contagious to humans – Symptoms include fever, muscle pain, and massive internal bleeding – Death rate is 90 percent © Cengage Learning 2015 How Do Viruses Affect Human Health? • Viral recombination – Viruses have genomes that can mutate – RNA viruses can mutate quickly – Viral genomes can also exchange genes when two viruses infect a host at the same time © Cengage Learning 2015 How Do Viruses Affect Human Health? • Viral recombination – Avian influenza H5N1 (bird flu) occasionally infects people who are in contact with birds, and has a high mortality rate – Influenza H1N1 (swine flu) first appeared in 2009, can cause severe respiratory symptoms, and is easily transmitted © Cengage Learning 2015 How important is long-distance travel in spread of epidemics? November 5, 2014 When modeling the spread of epidemics, such as the Ebola outbreak, scientists must take into account the longdistance hops now possible with international air travel. But how important are such long-distance jumps? A new model by biophysicists shows that how common long-range jumps are makes a big difference in the dispersal of a disease, that is, whether you get slow, rippling versus rapid metastatic spread. Yet knowing how to predict the spread of these epidemics is still uncertain, because the complicated models used are not fully understood, says a UC Berkeley biophysicist. Using a very simple model of disease spread, Oskar Hallatschek, assistant professor of physics, proved that one common assumption is actually wrong. Most models have taken for granted that if disease vectors, such as humans, have any chance of "jumping" outside the initial outbreak area -- by plane or train, for example -- the outbreak quickly metastasizes into an epidemic. Hallatschek and co-author Daniel Fisher of Stanford University found instead that if the chance of long-distance dispersal is low enough, the disease spreads quite slowly, like a wave rippling out from the initial outbreak. This type of spread was common centuries ago when humans rarely traveled. The Black Death spread through 14thcentury Europe as a wave, for example. But if the chance of jumping is above a threshold level -- which is often the situation today with frequent air travel the diseases can generate enough satellite outbreaks to spread like wildfire. And the greater the chance that people can hop around the globe, the faster the spread. "With our simple model, we clearly show that one of the key factors that controls the spread of infection is how common long-range jumps are in the dispersal of a disease," said Hallatschek, who is the William H. McAdams Chair in physics and a member of the UC Berkeley arm of the California Institute for Quantitative Biosciences (QB3). "And what matters most are the rare cases of extremely long jumps, the individuals who take plane trips to distant places and potentially spread the disease." This new understanding of a simple computer model of disease spread will help epidemiologists understand the more complex models now used to predict the spread of epidemics, he said, but also help scientists understand the spread of cancer metastases, genetic mutations in animal or human populations, invasive species, wildfires and even rumors. © Cengage Learning 2015 19.4 How Are Bacteria and Archaea Similar? • Bacteria and archaea – Prokaryotes – Small, structurally simple and single-celled – Three cell shapes • Coccus (spherical) • Bacillus (rod-shaped) • Spirillum (spiral) © Cengage Learning 2015 How Are Bacteria and Archaea Similar? • Prokaryotic traits – Ribosomes distributed in the cytoplasm – Asexual reproduction by binary fission – Capacity for gene exchange among existing cells through conjugation, transduction, and transformation © Cengage Learning 2015 19.5 What Are Some Major Bacterial Lineages? • Bacteria are widespread, abundant, and diverse – Most either harmless or beneficial • Many bacteria have essential ecological roles: – Decomposers – Cycle nutrients – Form partnerships with other species © Cengage Learning 2015 19.6 How Do Bacteria Affect Human Health? • Normal flora – Normally harmless or beneficial microorganisms that typically live in or on a body • Some endospore-forming bacteria make deadly toxins: – Bacillus anthracis: anthrax – Clostridium tetani: tetanus – C. botulinum: botulism © Cengage Learning 2015 How Do Bacteria Affect Human Health? • Dangerous infections: – Mycobacterium tuberculosis: tuberculosis – Streptococcus: strep throat, “flesh-eating bacteria” – Staphylococcus: Antibiotic-resistant staph infections © Cengage Learning 2015 Biology Concepts and Applications | 9e Starr | Evers | Starr Chapter 20 The Protists © Cengage Learning 2015 © Cengage Learning 2015 © Cengage Learning 2015 20.1 What Are Protists? • Protists – Protists are a collection of mostly single-celled eukaryotes – Protists are not a natural group, but a collection of lineages, some only distantly related to one another – Many have chloroplasts © Cengage Learning 2015 What Are Protists? © Cengage Learning 2015 What Are Protists? • Chloroplasts evolved by endosymbiosis – Primary endosymbiosis – bacterium enters cell and descendants evolve into organelles – Secondary endosymbiosis – photosynthetic protist engulfed by a heterotrophic protist © Cengage Learning 2015 What Are Protists? primary endosymbiosis 1 Eukaryotic cell engulfs a cyanobacterium. © Cengage Learning 2015 The resulting chloroplast has two membranes. secondary endosymbiosis 2 Heterotrophic protist engulfs an autotrophic one with chloroplasts that evolved by primary endosymbiosis. The resulting chloroplast has four membranes. What Are Alveolates? • Dinoflagellates – Whirling aquatic heterotrophs and autotrophs – Have cellulose plates – Photosynthetic – Supply reef-building corals with sugars and oxygen – Some dinoflagellates are bioluminescent © Cengage Learning 2015 © Cengage Learning 2015 20.5 How Does Malaria Affect Human Health? • Malaria is a leading cause of human death, killing more than 1.3 million people every year • Plasmodium, a single-celled apicomplexan, causes malaria – Mosquitoes carry Plasmodium from one human host to another © Cengage Learning 2015 What Are Stramenopiles? • Brown algae – Multicelled marine protist – Range in size from microscopic strands to giant kelps – Contain the brown pigment fucoxanthin – Source of algins, used as thickeners and emulsifiers © Cengage Learning 2015 20.7 Which Protists are Closest To Plants? • Red algae – Photosynthetic protist – Most red algae are multicelled and marine – Deposit cellulose in cell walls – Store sugars as starch – Has chloroplasts containing chlorophyll a and red pigments called phycobilins • Pigments allow them to capture light even in deep waters © Cengage Learning 2015 Which Protists are Closest To Plants? • Green algae – Closest relatives of land plants • Charophyte algae (Chara): closest relatives; unlike most other green algae, divide by cell plate formation, and have plasmodesmata cytoplasmic connections – May be single cells, colonial, or multicelled • Some multicelled algae have an alternation of generations © Cengage Learning 2015 Green algae © Cengage Learning 2015 Red algae Brown algae Figure 15.25 – Seaweeds are classified into three different groups, based partly on the types of pigments present in their chloroplasts: • Green algae • Red algae • Brown algae (including kelp) © Cengage Learning 2015 Which Protists are Closest To Plants? • Alternation of generations: the process – The diploid gametophyte is sheetlike • Gametes form at its edges – Fertilization produces a diploid zygote – The zygote develops into a diploid sporophyte – Haploid spores form by meiosis on the sporophyte body, and are released – Spores germinate and develop into a new gametophyte © Cengage Learning 2015 20.10 Algal Blooms • Harmful algal bloom (HAB) – A population explosion of an aquatic protist, or of another aquatic microorganism – Toxins released during some algal blooms can harm wildlife and endanger human health • Keeping harmful algal toxins out of the human food supply requires constant vigilance – Nutrients in water (fertilizers, farm waste, sewage) can cause runaway algal growth – Sometimes called “red tides” © Cengage Learning 2015 Pfiesteria piscicida Red = toxic stages, yellow = possibly toxic stages, blue = passive stages © Cengage Learning 2015 Unicellular protist Gamete Locomotor cells Food-synthesizing cells Somatic cells Colony Early multicellular organism with specialized, interdependent cells © Cengage Learning 2015 Later organism with gametes and somatic cells Figure 15.26-3 Bacteria Prokaryotes Archaea Protists Eukarya Plants Fungi Animals © Cengage Learning 2015 Figure 15.UN01