Chapter 1

Properties of Life Living organisms: – are composed of cells – are complex and ordered – respond to their environment – can grow and reproduce – obtain and use energy – maintain internal balance – allow for evolutionary adaptation 2

Levels of Organization Cellular Organization cells organelles molecules atoms The cell is the basic unit of life. 3

Levels of Organization Organismal Level organism organ systems organs tissues 4

Levels of Organization Population Level ecosystem community species population 5

Levels of Organization Each level of organization builds on the level below it but often demonstrates new features. Emergent properties: new properties present at one level that are not seen in the previous level 6

The Nature of Science Science aims to understand the natural world through observation and reasoning. Science begins with observations, therefore, much of science is purely descriptive. Science uses both deductive and inductive reasoning. 7

The Nature of Science Deductive reasoning uses general principles to make specific predictions. Inductive reasoning uses specific observations to develop general conclusions. 8

Reasoning What is Deductive Reasoning? Deductive reasoning is one of the two basic forms of valid reasoning, the other one being inductive reasoning. The main difference between these two types of reasoning is that, inductive reasoning argues from a specific to a general base whereas deductive reasoning goes from a general to a specific instance. Also, deductive reasoning, unlike inductive reasoning, is something that is based on a premise and then follows accordingly. Inductive and deductive arguments differ with regard to the standards of evaluation that are applicable to them. Thus, deductive reasoning is the method by which conclusions are drawn on the basis of proofs and not merely by assuming or thinking about a predetermined clause. The basic principle on whichthinking All X are Y (premise) All Y are Z (premise) Hence, all X are Z All oranges are fruits All fruits grow on trees Therefore, all oranges grow on trees 9

INDUCTIVE REASONING While deductive reasoning goes from general to specific, inductive reasoning goes from specific to general. In simple words, it is a form of reasoning which begins with a specific argument and arrives at a general logical conclusion. In many cases, induction is termed as 'strong' and 'weak' on the basis of the credibility of the argument put forth. 10

INDUCTIVE REASONING 2 Example of Strong Inductive Reasoning All the tigers observed in a particular region have yellow black stripes, therefore all the tigers native to this region have yellow stripes. Even though all the tigers that were observed sported yellow black stripes, the existence of a tiger with black and white stripes cannot be ruled out. Taking that into consideration, we can assume that the conclusion given in this example is not certain. However, the fact that the chances of coming across a white tiger are rare owing to which we can accept this argument, and thus it qualifies to be a good example of strong induction. Simply put a strong induction is one wherein the conclusion is backed by the premises to a significant extent. Examples of Weak Inductive Reasoning I always jump the red light, therefore everybody jumps the red light. concluding that everybody jumps the red light just because one person does so is not at all an exercise of logical thinking. Simply put, a weak induction has a faulty logic in the backdrop.thinking 11

The Nature of Science Scientists use a systematic approach to gain understanding of the natural world. -Observation -Hypothesis formation -Prediction -Experimentation -Conclusion 12

The Nature of Science A hypothesis is a possible explanation for an observation. A hypothesis -must be tested to determine its validity -is often tested in many different ways -allows for predictions to be made 13

The Nature of Science The experiment -tests the hypothesis -must be carefully designed to test only one variable at a time -consists of a test experiment and a control experiment 14

The Nature of Science If the hypothesis is valid, the scientist can predict the result of the experiment. Conducting the experiment to determine if it yields the predicted result is one way to test the validity of the experiment. 15

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The Nature of Science Scientists may use reductionism - to break a complex process down to its simpler parts models – to simulate phenomena that are difficult to study directly 17

The Nature of Science A scientific theory -is a body of interconnected concepts -is supported by much experimental evidence and scientific reasoning -expresses ideas of which we are most certain 18

Charles Darwin Served as naturalist on mapping expedition around coastal South America. Used many observations to develop his ideas Proposed that evolution occurs by natural selection 19

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Charles Darwin evolution: modification of a species over generations -“descent with modification” natural selection: individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than those without such characteristics 21

Darwin’s Evidence Similarity of related species - Darwin noticed variations in related species living in different locations 22

Darwin’s Evidence Population growth vs. availability of resources -population growth is geometric -increase in food supply is arithmetic 23

Darwin’s Evidence Population growth vs. availability of resources - Darwin realized that not all members of a population survive and reproduce. -Darwin based these ideas on the writings of Thomas Malthus. 24

Post-Darwin Evolution Evidence Fossil record - New fossils are found all the time - Earth is older than previously believed Mechanisms of heredity - Early criticism of Darwin’s ideas were resolved by Mendel’s theories for genetic inheritance. 25

Post-Darwin Evolution Evidence Comparative anatomy - Homologous structures have same evolutionary origin, but different structure and function. - Analogous structures have similar structure and function, but different evolutionary origin. 26

ORIGIN OF LIMBS 27

Homologous Structures 28

Analogy An analogy is a trait or an organ that appears similar in two unrelated organisms. The cladistic term for the same phenomenon is homoplasy, from Greek for same form. Biological anologies are often the result of convergent evolution. cladisticGreekconvergent evolution [edit]Analogies in taxonomyedit The classical example of an analogy is the ability to fly in birds and bats. Both groups can move by powered flight, but flight has evolved independently in the two groups. The ability to fly does not make birds and bats close relatives. The opposite of analogy is homology, where the ability or organ in question has been inherited from a common ancestor.birdsbatshomology [edit]Similar problems - similar solutionsedit Analogous traits will often arise due to convergence, where different species live in similar ways and/or similar environment, and thus face the same environmental factors. Both herrings and dolphins are streamlined. Both are active predators in a high drag environment, but the herring is a bony fish, the dolphin a mammal. In the Mesozoic, similarly streamlined ichthyosaurs navigated the worlds oceans, yet another example of a group evolving a similar shape due to the same environmental factors. A similar phenomenon is earless seals andeared seals. It was long debated whether the two groups are a single marine group, or represent two separate episodes of carnivorans turning to a marine environment. [2]convergence herringsdolphinspredatorsdragbony fishmammalMesozoicichthyosaursearless sealseared sealscarnivorans [2] 29

The classical example of an analogy is the ability to fly in birds and bats. Both groups can move by powered flight, but flight has evolved independently in the two groups. The ability to fly does not make birds and bats close relatives. The opposite of analogy is homology, where the ability or organ in question has been inherited from a common ancestor.birdsbatshomology 30

Post-Darwin Evolution Evidence Molecular Evidence - Our increased understanding of DNA and protein structures has led to the development of more accurate phylogenetic trees. 31

Unifying Themes in Biology Cell theory - All living organisms are made of cells, and all living cells come from preexisting cells. Molecular basis of inheritance - DNA encodes genes which control living organisms and are passed from one generation to the next. 32

Unifying Themes in Biology Structure and Function -The proper function of a molecule is dependent on its structure. -The structure of a molecule can often tell us about its function. 33

Unifying Themes in Biology Evolutionary change - Living organisms have evolved from the same origin event. The diversity of life is the result of evolutionary change. Evolutionary conservation - Critical characteristics of early organisms are preserved and passed on to future generations. 34

35 Cells - information processing systems - Cells process information stored in DNA as well as information received from the environment. Emergent properties - New properties are present at one level of organization that are not seen in the previous level.

36 CHAPTER 1 INTRODUCTION: THE ORIGIN OF LIFE CONCEPTS: 1.Biology: Methods to study biology and Pioneers 2.Characteristics of Cells and Cell Theory 3.Prokaryotes and Eukaryotes 4.Viruses

Introduction Biology-The study of the life. Scientific Method (OHEC) Reasoning: Deductive and Inductive Discovery of Cells Robert Hooke, Anton Van Leeuwenhoek Basic Properties of Cells Can grow and reproduce in culture Undergo biochemical processes and are regulated Contain genetic materials and respond to stimuli 37

38 Cell Theory: Schleiden, Schwann and Virchow Two fundamental classes of Cells Prokaryotes-all bacteria: Arose 3.5 billion years ago, some are photosynthetic Eukaryotes- protists, fungi, plants and animals: Arose 1.5 billion years ago Characteristics of Prokaryotes vs Eukaryotes Complexity: simple (P), complex (E) Genetic Material: Located in Nucloid region (P), Nucleus (E).

39 Characteristics of Prokaryotes vs Eukaryotes Cytoplasm: membrane-bound organelles and cytoskeletal proteins (E), neither in prokaryotes, 70S ribosomes (P) and 80S (E). Subkingdoms of Prokaryotes: Archaebacteria: Eubacteria: mycoplasma, cyanobacteria, E.coli, etc.

Viruses Viruses: Obligatory Parasites, Virion-viral particle outside host. Origin: from host Genome Protein capsid surrounds genome Eukaryotic viruses have envolupes Infections: Lytic or Lysogenic (provirus) HIV: Lysogenic, budding, host may become malignant. Other infectious agents: viroid (plants), prions (animals) 40

Overview of the Emergence of cells and infectious agents (Prokaryotes) Archaebacteria  Eubacteria  mitochondrion and chloroplast  Eukaryotes  Viruses and other infectious agents 41

42 CHAPTER 1 INTRODUCTION: THE ORIGIN OF LIFE CONCEPTS: 1.Biology: Methods to study biology and Pioneers 2.Characteristics of Cells and Cell Theory 3.Prokaryotes and Eukaryotes 4.Viruses

Introduction Biology-The study of the life. Scientific Method (OHEC) Reasoning: Deductive and Inductive Discovery of Cells Robert Hooke, Anton Van Leeuwenhoek Cell Theory Cells are the basic unit of life All organisms are composed of one or more cells Cells come from pre-existing cells 43

44 Cell Theory: Schleiden, Schwann and Virchow Two fundamental classes of Cells Prokaryotes-all bacteria: Arose 3.5 billion years ago, some are photosynthetic Eukaryotes- protists, fungi, plants and animals: Arose 1.5 billion years ago Characteristics of Prokaryotes vs Eukaryotes Complexity: simple (P), complex (E) Genetic Material: Located in Nucloid region (P), Nucleus (E).

45 Characteristics of Prokaryotes vs Eukaryotes Cytoplasm: membrane-bound organelles and cytoskeletal proteins (E), neither in prokaryotes, 70S ribosomes (P) and 80S (E). Subkingdoms of Prokaryotes: Archaebacteria: Eubacteria: mycoplasma, cyanobacteria, E.coli, etc.

Viruses: Obligatory Parasites, Virion-viral particle outside host. Origin: from host GenomeProtein capsid surrounds genome Eukaryotic viruses have envolupes Infections: Lytic or Lysogenic (provirus) HIV: Lysogenic, budding, host may become malignant. Other infectious agents: viroid (plants), prions (animals) 46

Overview of the Emergence of cells and infectious agents (Prokaryotes) Archaebacteria  Eubacteria  mitochondrion and chloroplast  Eukaryotes  Viruses/ virion and other infectious agents (viroids and prions) 47

Learn the cell Evolution Chart 48