chapter 1 properties of life living organisms: – are composed of cells – are complex and ordered...

Chapter 1

Properties of LifeLiving 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

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Levels of OrganizationCellular Organization

cells organelles

molecules atoms

The cell is the basic unit of life.

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Levels of OrganizationOrganismal Level

organism organ systems

organstissues

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Levels of OrganizationPopulation Level ecosystem

community species

population

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Levels of OrganizationEach 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

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The Nature of ScienceScience 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.

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The Nature of ScienceDeductive reasoning uses general principles

to make specific predictions.

Inductive reasoning uses specific observations to develop general conclusions.

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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 which

All X are Y (premise)All Y are Z (premise)Hence, all X are Z

All oranges are fruitsAll fruits grow on treesTherefore, all oranges grow on trees 9

INDUCTIVE REASONINGWhile 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.

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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.

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The Nature of ScienceScientists use a systematic approach to gain

understanding of the natural world.

-Observation-Hypothesis formation-Prediction-Experimentation-Conclusion

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The Nature of ScienceA 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

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The Nature of ScienceThe 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

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The Nature of ScienceIf 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.

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The Nature of ScienceScientists may use

reductionism - to break a complex process down to its simpler parts

models – to simulate phenomena that are difficult to study directly

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The Nature of ScienceA 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

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Charles DarwinServed as naturalist on mapping expedition

around coastal South America.

Used many observations to develop his ideas

Proposed that evolution occurs by natural selection

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Charles Darwinevolution: 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

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Darwin’s EvidenceSimilarity of related species

- Darwin noticed variations in related species living in different locations

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Darwin’s EvidencePopulation growth vs. availability of resources

-population growth is geometric

-increase in foodsupply is arithmetic

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Darwin’s EvidencePopulation 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.

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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.

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Post-Darwin Evolution EvidenceComparative anatomy- Homologous structures have same

evolutionary origin, but different structure and function.

- Analogous structures have similar structure and function, but different evolutionary origin.

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ORIGIN OF LIMBS

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Homologous Structures

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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.

[edit]Analogies in taxonomy 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.

[edit]Similar problems - similar solutions 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] 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.

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Post-Darwin Evolution EvidenceMolecular Evidence

- Our increased understanding of DNA and protein structures has led to the development of more accurate phylogenetic trees.

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Unifying Themes in BiologyCell 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.

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Unifying Themes in BiologyStructure 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.

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Unifying Themes in BiologyEvolutionary 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.

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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.

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CHAPTER 1INTRODUCTION: 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

IntroductionBiology-The study of the life.Scientific Method (OHEC)Reasoning: Deductive and InductiveDiscovery of CellsRobert Hooke, Anton Van LeeuwenhoekBasic Properties of CellsCan grow and reproduce in cultureUndergo biochemical processes and are

regulatedContain genetic materials and respond to

stimuli

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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).

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•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.

VirusesViruses: Obligatory Parasites, Virion-

viral particle outside host. Origin: from host

GenomeProtein capsid surrounds genomeEukaryotic viruses have envolupesInfections: 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

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CHAPTER 1INTRODUCTION: 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

IntroductionBiology-The study of the life.Scientific Method (OHEC)Reasoning: Deductive and InductiveDiscovery of CellsRobert Hooke, Anton Van Leeuwenhoek Cell TheoryCells are the basic unit of lifeAll organisms are composed of one or more cellsCells come from pre-existing cells

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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


•Complexity: simple (P), complex (E)

•Genetic Material: Located in Nucloid region (P), Nucleus (E).

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•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)

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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)

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Learn the cell Evolution Chart

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