Chapter 1. Introduction: Biology Today. THE SCOPE OF LIFE The Properties of Life. Properties of Life: Biology is the scientific study of life.

Transcription

1 Chapter 1 Introduction: Biology Today 1 PowerPoint Lectures for Campbell Essential Biology, Fifth Edition, and Campbell Essential Biology with Physiology, Fourth Edition Eric J. Simon, Jean L. Dickey, and Jane B. Reece Lectures by Edward J. Zalisko THE SCOPE OF LIFE The Properties of Life 2 Biology is the scientific study of life. What is life? The study of biology encompasses a wide scale of size and a huge variety of life, both past and present. Properties of Life: 3 1) Order 2) Regulation 3) Growth and delopment 4) Energy Processing 5) Respons to the Environment 6) Reproduction 7) Evolution 1

2 Properties of Life: 4 1) Order All living things exhibit complex but ordered organization Properties of Life: 5 2) Regulation The environment outside an organism may change drastically, but the organism can adjust its internal environment, Properties of Life: 6 3) Growth and development Information carried by DNA controls the pattern of growth and development 2

3 Properties of Life: 7 4) Energy processing Organisms take in energy and use it to perform all of life s activities; they emit energy as heat Properties of Life: 8 5) Response to the environment All organisms respond to environmental stimuli. Properties of Life: 9 6) Response to the environment Organisms reproduce their own kind 3

4 Properties of Life: 10 7) Evolution Reproduction underlies the capacity of populations to change (evolve) over time. Life at Its Many Levels 11 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. Life at Its Many Levels 12 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells Emergent properties: At each level novel properties emerge from the specific arrangement and interactions of the parts in an increasingly sophisticated system. In simple terms the sum is greater than the parts Car analogy 9) Organelles 10) Molecules and Atoms 4

5 Life at Its Many Levels 13 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms Life at Its Many Levels 14 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms Life at Its Many Levels 15 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms 5

6 Life at Its Many Levels 16 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms Life at Its Many Levels 17 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms Life at Its Many Levels 18 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms 6

7 Life at Its Many Levels 19 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms Life at Its Many Levels 20 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms Life at Its Many Levels 21 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities 4) Populations Nucleus 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms 7

8 Life at Its Many Levels 22 Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. 1) Biosphere 2) Ecosystems 3) Communities Atom 4) Populations 5) Organisms 6) Organ Systems and Organs 7) Tissues 8) Cells 9) Organelles 10) Molecules and Atoms Ecosystems 23 Each organism interacts continuously with its environment. Organisms interact continuously with the living and nonliving factors in the environment. All the living organisms in a specific area, along with all of the nonliving factors with which they interact, form an ecosystem. Ecosystems 24 The dynamics of any ecosystem depend on two main processes: recycling of chemical nutrients and flow of energy. Within ecosystems nutrients are recycled but energy flows through. 8

9 Figure Inflow of light energy ECOSYSTEM Outflow of heat energy Consumers (animals) Chemical energy (food) Producers (plants and other photosynthetic organisms) Cycling of nutrients Decomposers (in soil) Cells and Their DNA 26 The cell is the level at which the properties of life emerge. Cells are the lowest level of structure that can perform all activities required for life. All organisms are composed of cells. Cells are the subunits that make up multicellular organisms such as humans and trees. Cells and Their DNA 27 All cells share many characteristics. All cells are enclosed by a membrane that regulates the passage of materials between the cell and its surroundings. Every cell uses DNA as its genetic information. 9

10 Colorized TEM Cells and Their DNA 28 We can distinguish two major types of cells: 1. The prokaryotic cell is simpler and usually smaller and characteristic of bacteria. 2. The eukaryotic cell is subdivided by internal membranes into different functional compartments called organelles and found in plants and animals. Figure Prokaryotic cell (bacterium) Smaller Simpler structure DNA concentrated in nucleoid region, which is not enclosed by membrane Lacks most organelles Nucleoid region Organelles Eukaryotic cell Larger More complex structure by membrane Nucleus enclosed Contains many types of organelles Nucleus Cells and Their DNA 30 All cells use DNA as the chemical material of genes, the units of inheritance that transmit information from parents to offspring. The chemical language of DNA is common to all organisms and consists of just four molecular building blocks with names that are abbreviated as A, G, C, T. 10

11 Figure The four chemical building blocks of DNA A DNA molecule Cells and Their DNA 32 Genetic engineering has transformed the pharmaceutical industry and extended millions of lives. Figure

12 Cells and Their DNA 34 The entire book of genetic instructions that an organism inherits is called its genome. The nucleus of each human cell packs a genome that is about 3 billion chemical letters long. Life in Its Diverse Forms 35 Diversity is a hallmark of life. The diversity of known life includes about 1.8 million species that biologists have identified and named. Estimates of the total number of species range from 10 million to over 100 million. Figure

13 Grouping Species: The Basic Concept 37 Biodiversity can be beautiful but overwhelming. Categorizing life into groups helps us deal with this complexity. Taxonomy is the branch of biology that names and classifies species. It formalizes the hierarchical ordering of organisms into broader and broader groups. The Three Domains of Life 38 The three domains of life are Bacteria, Archaea, and Eukarya. Bacteria and Archaea have prokaryotic cells. Eukarya have eukaryotic cells. The Three Domains of Life 39 Eukarya include Kingdom Plantae, Kingdom Fungi, Kingdom Animalia, and Protists (multiple kingdoms). Most plants, fungi, and animals are multicellular. Protists are generally single-celled. 13

14 DOMAIN EUKARYA DOMAIN ARCHAEA DOMAIN BACTERIA The Three Domains of Life 40 These three multicellular kingdoms are distinguished by how they obtain food. Plants produce their own sugars and other foods by photosynthesis. Fungi are mostly decomposers, digesting dead organisms. Animals obtain food by ingesting (eating) and digesting other organisms. Figure Kingdom Plantae Kingdom Fungi Kingdom Animalia Protists (multiple kingdoms) Unity in the Diversity of Life 42 Underlying the diversity of life is a striking unity, especially at the lower levels of biological organization. For example, all life uses the genetic language of DNA. 14

15 - Genome-wide variation from one human being to another can be up to 0.5% (99.5% similarity) 43 - Chimpanzees are 96% to 98% similar to humans, depending on how it is calculated. - Cats have 90% of homologous genes with humans, 82% with dogs, 80% with cows, 79% with chimpanzees, 69% with rats and 67% with mice. - Cows (Bos taurus) are 80% genetically similar to humans - 75% of mouse genes have equivalents in humans, 90% of the mouse genome could be lined up with a region on the human genome 99% of mouse genes turn out to have analogues in humans - The fruit fly (Drosophila) shares about 60% of its DNA with humans - About 60% of chicken genes correspond to a similar human gene. Unity in the Diversity of Life 44 Underlying the diversity of life is a striking unity, especially at the lower levels of biological organization. For example, all life uses the genetic language of DNA. Biological evolution accounts for this combination of unity and diversity. EVOLUTION: BIOLOGY S UNIFYING THEME 45 The history of life is a saga of a constantly changing Earth billions of years old. Fossils document this history. 15

16 Figure EVOLUTION: BIOLOGY S UNIFYING THEME 47 Life evolves. Each species is one twig of a branching tree of life extending back in time through ancestral species more and more remote. Species that are very similar, such as the brown bear and polar bear, share a more recent common ancestor. Figure Giant panda Ancestral bear Spectacled bear Sloth bear Common ancestor of all modern bears Sun bear American black bear Asiatic black bear Common ancestor of polar bear and brown bear Polar bear Brown bear Millions of years ago 16

17 The Darwinian View of Life 49 The evolutionary view of life came into focus in 1859 when Charles Darwin published On the Origin of Species by Means of Natural Selection. Figure 1.11a 50 The Darwinian View of Life 51 Darwin s book developed two main points: 1. Species living today descended from a succession of ancestral species in what Darwin called descent with modification, capturing the duality of life s unity (descent) and diversity (modification). 2. Natural selection is the mechanism for descent with modification. 17

18 Natural Selection 52 Darwin was struck by the diversity of animals on the Galápagos Islands. He thought that adaptation to the environment and the origin of new species were closely related processes. As populations separated by a geographic barrier adapted to local environments, they became separate species. Darwin s Inescapable Conclusion 53 Darwin synthesized the theory of natural selection from two observations that were neither profound nor original. Others had the pieces of the puzzle, but Darwin could see how they fit together. Darwin s Inescapable Conclusion 54 Observation 1: Overproduction and competition Observation 2: Individual variation Conclusion: Unequal reproductive success It is this unequal reproductive success that Darwin called natural selection. The product of natural selection is adaptation. Natural selection is the mechanism of evolution. 18

19 Figure 1.12a 55 1 Population with varied inherited traits 2 Elimination of individuals with certain traits Figure 1.12b 56 3 Reproduction of survivors 4 Increasing frequency of traits that enhance survival and reproductive success Adaptation 57 The beetles are said to have adapted to their environment However, it is the beetle population that evolved and adapted. Individuals do not evolve. 19

20 Observing Artificial Selection 58 Artificial selection vs natural selection Artificial selection is the selective breeding of domesticated plants and animals by humans. In artificial selection, humans do the selecting instead of the environment. Figure 1.13a 59 (a) Vegetables descended from wild mustard Wild mustard Cabbage from end buds Brussels sprouts from side buds Kohlrabi from stems Kale from leaves Broccoli from flowers and stems Cauliflower from flower clusters Figure 1.13b 60 (b) Domesticated dogs descended from wolves Gray wolves Domesticated dogs 20

21 Observing Natural Selection 61 There are many examples of natural selection in action. In Galápagos finches, beak size becomes better suited to the size and shape of available seeds. Antibiotic-resistance in bacteria evolves in response to the overuse of antibiotics. Observing Natural Selection 62 Darwin s publication of The Origin of Species fueled an explosion in biological research. Evolution is one of biology s best demonstrated, most comprehensive, and longest-lasting theories. Evolution is the unifying theme of biology. THE PROCESS OF SCIENCE 63 The word science is derived from a Latin verb meaning to know. Science is a way of knowing, based on inquiry. Science developed from our curiosity about ourselves and the world around us. 21

22 THE PROCESS OF SCIENCE 64 There are two main scientific approaches: Discovery science is mostly about describing nature. Hypothesis-driven science is mostly about explaining nature. Discovery Science 65 Science seeks natural causes for natural phenomena. This limits the scope of science to the study of structures and processes that we can observe and measure directly or indirectly. The dependence on observations that people can confirm demystifies nature and distinguishes science from belief in the supernatural. Discovery Science 66 Verifiable observations and measurements are the data of discovery science. In biology, discovery science enables us to describe life at its many levels, from ecosystems down to cells and molecules. 22

23 Figure 1.14a 67 Figure 1.14b 68 Discovery Science 69 Discovery science can stimulate us to ask questions and seek explanations and uses a process of inquiry called the scientific method, consisting of a series of steps that provide a loose guideline for scientific investigations. 23

24 Hypothesis-Driven Science 70 Most modern scientific investigations can be described as hypothesis-driven science. A hypothesis is a tentative answer to a question an explanation on trial. Although we don t think of it in those terms, we use hypotheses in solving everyday problems, like figuring out why a TV remote fails. Hypothesis-Driven Science 71 Once a hypothesis is formed, an investigator can use logic to test it. A hypothesis is tested by performing an experiment to see whether results are as predicted. This deductive reasoning takes the form of If then logic. Hypothesis-Driven Science 72 The mysterious case of the broken remote Observation The remote doesn t work. Question What s wrong? Hypothesis The batteries are dead. Prediction With new batteries, it will work. 24

25 Hypothesis-Driven Science 73 The mysterious case of the broken remote Observation The remote doesn t work. Question What s wrong? Hypothesis The batteries are dead. Prediction With new batteries, it will work. Experiment Replace batteries. Experiment supports hypothesis; make more predictions and test. Hypothesis-Driven Science 74 Revise. Experiment does not support hypothesis. Observation The remote doesn t work. Question What s wrong? Hypothesis The batteries are dead. Prediction With new batteries, it will work. Experiment Replace batteries. Experiment supports hypothesis; make more predictions and test. The Process of Science: Are Trans Fats Bad for You? One way to better understand how the process of science can be applied to real-world problems is to examine a case study, an in-depth examination of an actual investigation. 25

26 The Process of Science: Are Trans Fats Bad for You? 76 Dietary fat comes in different forms. Trans fats are a non-natural form produced through manufacturing processes called hydrogenation. Trans fats add texture, increase shelf life, and are inexpensive to prepare. The Process of Science: Are Trans Fats Bad for You? 77 A study of 120,000 female nurses found that a diet with high levels of trans fats nearly doubled the risk of heart disease. The Process of Science: Are Trans Fats Bad for You? 78 A hypothesis-driven study published in 2004 started with the observation that human body fat retains traces of consumed dietary fat, asked the question Would the adipose tissue of heart attack patients be different from a similar group of healthy patients? formed the hypothesis healthy patients body fat would contain less trans fats than the body fat in heart attack victims. 26

27 Trans fats in adipose tissue (g trans fat per 100 g total fat) The Process of Science: Are Trans Fats Bad for You? 79 Design experiment: The researchers set up an experiment to determine the amounts of fat in the adipose tissue of 79 patients who had experienced a heart attack. Collect data and analyze: They compared these patients to the data for 167 patients who had not experienced a heart attack. This is an example of a controlled experiment in which the control and experimental groups differ only in one variable the occurrence of a heart attack. The Process of Science: Are Trans Fats Bad for You? 80 The results showed significantly higher levels of trans fats in the bodies of the heart attack patients. Figure Heart attack patients Control group 27

28 The Process of Science: Are Trans Fats Bad for You? 82 The results showed significantly higher levels of trans fats in the bodies of the heart attack patients. You would do well to read nutrition labels and avoid trans fats as much as possible in your own diet. Theories in Science 83 What is a scientific theory, and how is it different from a hypothesis? A scientific theory is much broader in scope than a hypothesis. Theories only become widely accepted in science if they are supported by an accumulation of extensive and varied evidence. Theories in Science 84 Scientific theories are not the only way of knowing nature. Science, religion, and art are very different ways of trying to make sense of nature. 28

29 The Culture of Science 85 Scientists build on what has been learned from earlier research. They pay close attention to contemporary scientists working on the same problem. Cooperation and competition characterize the scientific culture. Scientists check the conclusions of others by attempting to repeat experiments. Scientists are generally skeptics. Science, Technology, and Society 86 Science and technology are interdependent. New technologies advance science. Scientific discoveries lead to new technologies. For example, the discovery of the structure of DNA about 60 years ago led to a variety of DNA technologies. Figure

30 The Culture of Science 88 Science has two key features that distinguish it from other forms of inquiry. Science depends on observations and measurements that others can verify and requires that ideas (hypotheses) are testable by experiments that others can repeat. Figure Science, Technology, and Society 90 Technology has improved our standard of living in many ways, but it is a double-edged sword. Technology that keeps people healthier has enabled the human population to double to 7 billion in just the past 40 years. The environmental consequences of this population growth may be devastating. 30

31 Evolution Connection: Evolution in Our Everyday Lives 91 Antibiotics are drugs that help cure bacterial infections. When an antibiotic is taken, most bacteria are typically killed. Those bacteria most naturally resistant to the drug can still survive. Those few resistant bacteria can soon multiply and become the norm and not the exception. Evolution Connection: Evolution in Our Everyday Lives 92 The evolution of antibiotic-resistant bacteria is a huge problem in public health. Antibiotics are being used more selectively. Many farmers are reducing the use of antibiotics in animal feed. Evolution Connection: Evolution in Our Everyday Lives 93 It is important to note that the adaptation of bacteria to an environment containing an antibiotic does not mean that the drug created the antibiotic resistance. Instead, the environment screened the heritable variations that already existed among the existing bacteria. 31

32 Colorized SEM Figure