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LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 1 Introduction: Themes in the Study of Life Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Overview: Inquiring About Life • An organism’s adaptations to its environment are the result of evolution – the mother of pearl plant’s thick, succulent leaves are adaptations to conserving water; this helps it to survive in the crevices of rock walls • Evolution is the process of change that has transformed life on Earth • but many questions remain about these changes • asking these questions and finding the science-based answers is BIOLOGY • Biology is the scientific study of life • Biologists ask questions such as – How does a single cell develop into an organism? – How does the human mind work? – How do living things interact in communities? • Life defies a simple, one-sentence definition What is Life? 1. movement: internal & external 2. responsiveness & adaptation to environment 3. growth 4. reproduction 5. digestion & energy processing 6. absorption 7. secretion 8. circulation 9. order 10. regulation Order Response to the environment Evolutionary adaptation Reproduction Regulation Energy processing Growth and development Requirements for Life: 1. water 2. food 3. oxygen 4. heat 5. pressure Concept: The themes of this book make connections across different areas of biology • Biology consists of more than memorizing factual details • Themes help to organize biological information Theme #1: New Properties Emerge at Each Level in the Biological Hierarchy • Life can be studied at different levels, from molecules to the entire living planet • The study of life can be divided into different levels of biological organization • starting with the biosphere and ending with the atom • as we proceed through these levels – different properties emerge 7. Tissues – group of cells that work together to perform specific functions 1. The biosphere – all life on Earth 2. Ecosystems – all living things in a particular area + all non-living components e.g. soil, water, atmosphere mesophyll leaf epidermis 6. Organs and organ systems – a part that carries out a specific function within an organism 8. Cells – life’s fundamental unit of structure & function 3. Communities – the entire array of organisms living within an ecosystem 9. Organelles – the functional components of a cell 5. Organisms – individual living things 4. Populations – all the living individuals of a species living within the bounds of an area e.g. population of sugar maple tress within a forest 11. Atoms 10. Molecules – a chemical structure consisting of two or more atoms Emergent Properties • novel properties emerge at each step along this hierarchy – the properties at each step are unique • known as emergent properties – result from the arrangement and interaction of parts within a system – due to the arrangement and interaction of parts as complexity increases – e.g. human brain – memories and thoughts are emergent properties of a complex network of nerve cells – e.g. photosynthesis occurs in chloroplasts – will not take place in a test tube containing a disorganized mixture of chlorophyll and other chloroplast molecules Emergent Properties • emergent properties are not unique to life • they can characterize nonbiological entities as well – for example, a functioning bicycle emerges only when all of the necessary parts connect in the correct way – the lead of a pencil and a diamond are both carbon – but the arrangement of their carbon atoms are different – leads to different properties The Power and Limitations of Reductionism • the complexity of emergent properties make them challenging to study – so we try to reduce them into something simpler • reductionism is the reduction of complex systems to simpler components that are more manageable to study • but you need to observe the interactions of these systems with others in order to fully understand them – e.g. studying the molecular structure of DNA helps us to understand the chemical basis of inheritance – but you need to study how DNA interacts with the proteins of the nuclear matrix Systems Biology • you must balance reductionism with a larger, more holistic approach to emergent systems • how cells, organisms and higher levels of order work together = goal of Systems Biology • a system = is a combination of components that function together • Systems biology constructs models for the dynamic behavior of whole biological systems – based on a study of the interactions among the system’s parts – the model allows for predictions when one variable changes • systems biology poses questions such as – how does a drug for blood pressure affect other organs? (physiological models) – how does increasing CO2 alter the biosphere? (ecosystem models) Theme #2: Organisms Interact with Other Organisms and the Physical Environment • in an ecosystem - every organism interacts with its environment, including nonliving factors and other organisms – e.g. leaves of a tree take up CO2 and release O2 to the air – humans utilize this O2 Sunlight • both organisms and their environments are affected by the interactions between them – some of these interactions can be harmful – e.g. greenhouse gases Leaves absorb light energy from the sun. CO2 Leaves take in carbon dioxide from the air and release oxygen. O2 Cycling of chemical nutrients Leaves fall to the ground and are decomposed by organisms that return minerals to the soil. Water and minerals in the soil are taken up by the tree through its roots. Animals eat leaves and fruit from the tree. Theme #3: Life Requires Energy Transfer and Transformation • • • • a fundamental characteristic of living organisms is their use of energy to carry out life’s activities work, including moving, growing, and reproducing, requires a source of energy living organisms transform energy from one form to another – e.g. light energy is converted to chemical energy (i.e. sugar), chemical energy becomes kinetic energy (e.g. growth, reproduction, movement) energy flows through an ecosystem, usually entering as light and exiting as heat Sunlight Heat When energy is used to do work, some energy is converted to thermal energy, which is lost as heat. Producers absorb light energy and transform it into chemical energy. Chemical energy Chemical energy in food is transferred from plants to consumers. (a) Energy flow from sunlight to producers to consumers An animal’s muscle cells convert chemical energy from food to kinetic energy, the energy of motion. (b) Using energy to do work A plant’s cells use chemical energy to do work such as growing new leaves. Theme #4: Structure and Function Are Correlated at All Levels of Biological Organization • form fits function • so analyzing a biological structure gives us clues as to its function • structure and function of living organisms are closely related – e.g. a leaf is thin and flat, maximizing the capture of light by chloroplasts – e.g. the structure of a bird’s wing is adapted to flight (a) Wings (b) Wing bones Theme #5: The Cell Is an Organism’s Basic Unit of Structure and Function • the cell is the lowest level of organization that can perform all activities required for life • all cells: – are enclosed by a membrane – use DNA as their genetic information • a eukaryotic cell has membrane-enclosed organelles, the largest of which is Prokaryotic cell usually the nucleus Eukaryotic cell Membrane • by comparison, a prokaryotic cell is simpler and usually smaller, and does not contain a nucleus or other membrane-enclosed organelles DNA (no nucleus) Membrane Cytoplasm Membraneenclosed organelles Nucleus (membraneenclosed) DNA (throughout 1 m nucleus) Theme #6: The Continuity of Life Is Based on Heritable Information in the Form of DNA • the ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms • the dividing cell contains a specific form of genetic material = chromosomes – chromosomes contain most of a cell’s genetic material in the form of DNA (deoxyribonucleic acid) • DNA is the substance of genes • genes are the units of inheritance that transmit information from parents to offspring 25 m DNA Structure and Function • each chromosome is made up of one long DNA molecule with hundreds or thousands of genes – genes encode information for building proteins • DNA is inherited by offspring from their parents – one chromosome from each parent • DNA controls the development and maintenance of organisms Sperm cell Nuclei containing DNA Egg cell Fertilized egg with DNA from both parents Embryo’s cells with copies of inherited DNA Offspring with traits inherited from both parents • each DNA molecule is made up of two long chains arranged in a double helix • each link of a chain is one of four kinds of chemical building blocks called nucleotides and are nicknamed A, G, C, and T for the bases they carry • genes control protein production indirectly – DNA is transcribed into RNA then translated into a protein – known as a process called gene expression Nucleus A C DNA Nucleotide T A T Cell A C C G T A G T A (a) DNA double helix (b) Single strand of DNA Theme #7: Feedback Mechanisms Regulate Biological Systems Negative feedback • feedback mechanisms allow biological processes to self-regulate • Negative feedback means that as more of a product accumulates, the process that creates it slows and less of the product is produced A Enzyme 1 B Excess D blocks a step. D D Enzyme 2 D C Enzyme 3 D (a) Negative feedback Theme #7: Feedback Mechanisms Regulate Biological Systems Enzyme 4 • Positive feedback means that as more of a product accumulates, the process that creates it speeds up and more of the product is produced Positive feedback Excess Z stimulates a step. Z X Enzyme 5 Y Z Z Enzyme 6 Z (b) Positive feedback Evolution, the Overarching Theme of Biology • there is consensus among biologists as to the core theme of biology = Evolution – “Nothing in biology makes sense except in the light of evolution”—Theodosius Dobzhansky • evolution unifies biology at different scales of size throughout the history of life on Earth – evolution makes sense of everything we know about biology • organisms are modified descendants of common ancestors • evolution explains patterns of unity and diversity in living organisms • similar traits among organisms are explained by descent from common ancestors • differences among organisms are explained by the accumulation of heritable changes Classifying the Diversity of Life • diversity is a hallmark of life • approximately 1.8 million species have been identified and named to date, and thousands more are identified each year – – – – – 100,000 species of fungi 290,000 plant species 52,000 vertebrate species 1 million insect species untold numbers of single-cells species • estimates of the total number of species that actually exist range from 10 million to over 100 million • thousands of new species identified each year Grouping Species: The Basic Idea • taxonomy is the branch of biology that names and classifies species into groups of increasing breadth • domains, followed by kingdoms, are the broadest units of classification Species Genus Family Order Class Phylum Kingdom Domain Ursus americanus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Animalia Eukarya • in 1969: five-kingdom classification system – Robert Whittaker – recognized the existence of two fundamental cell types: prokaryotes and eukaryotes – created a separate kingdom for prokaryotes and divided up the eukaryotes – 1. Monera - prokaryotic – 2. Protista – unicellular organisms including algae – 3. Fungi – 4. Plantae – 5. Animalia – based on the nutritional requirements and methods of these domains • • • • plants = autotrophs fungus and animals = heterotrophs fungus = decomposers animals = digestors within the body • recently the application of molecular analysis to this classification has resulted in a reclassification 1 Billion years ago – some prokaryotes can differ dramatically from each other – as much as they differ from plants and animals – reorganization based on molecular data 0 Bacteria Eukarya gene transfer 2 3 common ancestor of all life 4 Origin of life Archaea • adoption of a three domain system of superkingdoms – 1. Bacteria – most of the currently known prokaryotes (or Eubacteria) – 2. Archaea – prokaryotes that inhabit a wide variety of environments – 3. Eukarya - eukaryotes • contains the “old” kingdoms of protists, fungi, plants and animals 2 m (b) Domain Archaea 2 m (a) Domain Bacteria (c) Domain Eukarya Kingdom Animalia 100 m Kingdom Plantae Protists Kingdom Fungi Unity in the Diversity of Life • as diverse as life is – there is a striking unity • unity is evident in many features of cells – e.g. cilia of a paramecium and a respiratory mucous cell • REASON: DNA is the universal genetic language common to all organisms – unity is evident in many features of cell structure 15 m 5 m Cilia of Paramecium Cilia of windpipe cells 0.1 m Cross section of a cilium, as viewed with an electron microscope • how do you account for the unity and diversity found in nature = Evolution • Evolution!!!! Evolution • three key observations about life – 1. organisms are suited for life in their environments – 2. many forms of life share characteristics – 3. life is diverse • 150 yrs ago – Charles Darwin developed a scientific explanation for these observations • published his theory in 1859 as the Origin of Species by Means of Natural Selection – from his work categorizing species as a member of the HMS Beagle Evolution • evolution = descent with modification • can also be defined as a change in the genetic composition of a population from generation to generation • pattern of evolutionary change is revealed by data taken from biology, geology, physics and chemistry Evolution is Descent with Modification • Darwin never used the term evolution • used the term descent with modification • proposed that similarities between organisms was due to descent from a common ancestor in the remote past • the descendants lived in various habitats developing adaptations to fit them to their habitat • called the mechanism of this evolutionary adaptation = Natural Selection three orchids showing variations on a common floral theme Artificial & Natural Selection • Natural selection was proposed as the mechanism explaining evolution • used artificial selection used by humans in breeding to explain his theory • made two observations: – 1. members of a population often vary in their inherited traits • SO: individuals whose inherited traits give them a higher probability of surviving and reproducing will leave more offspring – 2. all species can produce more offspring than their environment can support – many fail to survive • SO: the ability to survive and reproduce will lead to an accumulation of favorable inheritable traits • if these traits make your offspring more successful at coping with its environment = traits will persist over time = NATURAL SELECTION Natural Selection: a recap • 1. NS is a process in which individuals with certain heritable traits survive and reproduce at a higher rate than other individuals who don’t have those traits • 2. over time, NS can increase the match between organisms and their environment • 3. if an environment changes (or if an individual moves to a new environment), NS may result in adaptations • These new adaptations sometime give rise to new species. 1 Population with varied inherited traits 2 Elimination of individuals with certain traits 3 Reproduction of survivors 4 Increasing frequency of traits that enhance survival and reproductive success The Tree of Life • “Unity in diversity” arises from “descent with modification” – e.g. the forelimb of the bat, human, and horse and the whale flipper all share a common skeletal architecture • evolutionary relationships are often illustrated with treelike diagrams that show ancestors and their descendants – fossils provide additional evidence of anatomical unity from descent with modification Insect-eaters Green warbler finch Certhidea olivacea Gray warbler finch Certhidea fusca Bud-eater Seed-eater COMMON ANCESTOR Warbler finches Figure 1.22 Sharp-beaked ground finch Geospiza difficilis Vegetarian finch Platyspiza crassirostris Mangrove finch Cactospiza heliobates Insect-eaters Tree finches Woodpecker finch Cactospiza pallida Medium tree finch Camarhynchus pauper Large tree finch Camarhynchus psittacula Small tree finch Camarhynchus parvulus Cactus-flowereaters Seed-eaters Ground finches Large cactus ground finch Geospiza conirostris Cactus ground finch Geospiza scandens Small ground finch Geospiza fuliginosa Medium ground finch Geospiza fortis Large ground finch Geospiza magnirostris Concept: In studying nature, scientists make observations and then form and test hypotheses • The word science is derived from Latin and means “to know” • at the heart of science is inquiry – the search for information and explanation • in the search for answers, scientists use the scientific process • scientific process includes: – – – – – 1. making observations 2. forming logical hypotheses – that are testable and falsifiable 3. testing them 4. analysis of results 5. verification of hypothesis Types of Data • biologists use data to describe natural structures and processes • Data = recorded observations or items of information that fall into two categories – Qualitative data = descriptions rather than measurements • e.g. Jane Goodall’s observations of chimpanzee behavior – Quantitative data = recorded measurements • which are sometimes organized into tables and graphs Inductive Reasoning • collection of data leads to conclusions based on a type of logic called inductive reasoning • inductive reasoning draws conclusions through the logical process of induction • proper induction can lead to important generalizations • but these generalizations must be tested through testing or experimentation • an experiment requires two components: – 1. controls – something known you can compare your experimental results to – 2. repeatability - repeating specific observations Forming and Testing Hypotheses • observations and inductive reasoning can lead us to ask questions and propose hypothetical explanations called hypotheses • a hypothesis is a tentative answer to a well-framed question • a scientific hypothesis leads to predictions that can be tested by observation or experimentation • a scientific hypothesis must be falsifiable © 2011 Pearson Education, Inc. Observation: Your flashlight doesn’t work – Inquiry: Why doesn’t your flashlight work? – Inductive reasoning leads to two possible hypotheses: – Hypothesis 1: The batteries are dead – Hypothesis 2: The bulb is burnt out • Both these hypotheses are testable • good experimentation requires two components Observations – 1. controls – something known you can compare your experimental results to • • • • • • put in batteries that you KNOW are good did it work? NO then it might be the bulb put in a bulb that you KNOW is good did it work? YES THEN: it was the bulb – 2. repeatability – eliminates the possibility that your results are due to chance Question Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test of prediction Test of prediction Test falsifies hypothesis Test does not falsify hypothesis • hypothesis-based science often makes use of two or more alternative hypotheses • failure to prove one hypothesis does not prove another hypothesis – e.g. you replace your batteries and it still doesn’t work – this doesn’t mean it is the bulb – maybe you put your batteries in the wrong way Deductive Reasoning and Hypothesis Testing • inductive reasoning uses observations to make a hypothesis • deductive reasoning uses general premises to make specific predictions and test the hypothesis – used after the hypothesis has been developed – involves the use of IF/THEN statements – e.g. IF I put working batteries in my flashlight and it works (premise) THEN it was the batteries that were the problem (deductive prediction) – e.g. IF organisms are made of cells (premise 1), and humans are organisms (premise 2), THEN humans are composed of cells (deductive prediction) Questions That Can and Cannot Be Addressed by Science • A hypothesis must be: testable and falsifiable – for example, a hypothesis that ghosts fooled with the flashlight cannot be tested • Supernatural and religious explanations are outside the bounds of science © 2011 Pearson Education, Inc. Concept: Science benefits from a cooperative approach and diverse viewpoints • Most scientists work in teams, which often include graduate and undergraduate students • Good communication is important in order to share results through seminars, publications, and websites © 2011 Pearson Education, Inc. Building on the Work of Others • scientists check each others’ claims by performing similar experiments • it is not unusual for different scientists to work on the same research question • scientists cooperate by sharing data about model organisms and by sharing their results and conclusions • this course will discuss what we know using data that had been accumulated by numerous scientists all working together and building upon one another