Chapter 1 Lecture

CHAPTER 1

Introduction: Biology Today

PowerPoint® Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Neil Campbell, Jane Reece, and Eric Simon

Presentation prepared by Chris C. Romero Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• Biologists have identified about 1.7 million species of living organisms

• All organisms share a common chemical language for their genetic material, DNA Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• Scientists have  determined the complete  DNA sequences of  humans, puffer fish,  mosquitoes, and rice • Amoebas, molds, trees,  and people are all made  from similar cells

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• So, what is Biology?

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THE SCOPE OF BIOLOGY • Biology is the scientific study of life – Life is structured on a size scale ranging from the molecular to the global – Biology’s scope stretches across the enormous diversity of life on Earth

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A view of Earth from space A Central Park woodland

Approaching Central Park (the red rectangle in the middle of this photo)

An eastern gray squirrel Figure 1.2.1 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Life at Its Many Levels • Biologists explore life at levels ranging from the biosphere to the molecules that make up cells Cells

Nucleus within cell

Cells in squirrel DNA

Figure 1.2.2 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Hierarchy of Life • Biosphere – Consists of all the environments on Earth that support life – Examples include most regions of land, bodies of water, and the lower atmosphere

• Ecosystem – Consists of all the organisms living in a particular, as well as all the non-living physical components of the environment with which the organisms interact Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Sunlight

• The dynamics of any ecosystem depend on two processes – Cycling of nutrients

Ecosystem

Heat

Consumers (such as animals)

Heat

– Flow of energy

Producers (plants and other photosynthetic organisms)

Chemical energy (food)

Figure 1.3 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Hierarchy of Life • Community – The entire array of organisms inhabiting an ecosystem

• Population – An interacting group of one species

• Organism – An individual living thing

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Hierarchy of Life • Organ System – Consists of several organs that work together in performing a specific function – Examples include circulatory system, digestive system, or nervous system

• Organ – One or more groups of tissue coming together to form a functioning unit

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Hierarchy of Life • Tissue – A group of similar cells combined to form a functioning unit

• Cell – A unit of living matter separated from its environment by a boundary called a membrane

• Organelle – A structure that performs a specific function in a cell Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Hierarchy of Life • Molecule – A cluster of atoms held together by chemical bonds

• Atom – The smallest particle of ordinary matter

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Cells and Their DNA • The cell is the lowest level of structure that can perform all activities required for life – All organisms are composed of one or more cells

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• We can distinguish two major types of cells – Prokaryotic – Eukaryotic

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• The prokaryotic cell is simple and contains no organelles • The eukaryotic cell is more complex and contains organelles – The nucleus is the largest organelle in most eukaryotic cells

Nucleus (contains DNA)

Eukaryotic cell Prokaryotic cell

DNA (no nucleus) Organelles

Figure 1.4 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• All cells use DNA as the chemical material of genes – Genes are the units of inheritance that transmit information from parents to offspring

• The language of DNA contains just four letters – A, G, C, T Figure 1.5 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• Genetic engineering and biotechnology have allowed us to manipulate the DNA and genes of organisms

Figure 1.6 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Life in Its Diverse Forms • Diversity is the hallmark of life – The diversity of known life includes 1.7 million species – Estimates of the total diversity range from 5 million to over 30 million species

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Grouping Species: The Basic Concept • Biodiversity can be both beautiful and overwhelming • Taxonomy is the branch of biology that names and classifies species – It formalizes the hierarchical ordering of organisms Figure 1.7 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

The Three Domains of Life • The three domains of life are

Domain Bacteria

Domain Archaea

– Bacteria – Archaea

Domain Eukarya

– Eukarya Kingdom Protista

Kingdom Plantae

Kingdom Fungi

Kingdom Animalia Figure 1.8.1

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• Bacteria and Archaea are both prokaryotic domains

Domain Bacteria

Domain Archaea

Figure 1.8.2 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• Eukarya includes at least four kingdoms

Domain Eukarya

– Protista Kingdom Protista

Kingdom Plantae

Kingdom Fungi

Kingdom Animalia

– Plantae – Fungi – Animalia

Figure 1.8.3 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

EVOLUTION: BIOLOGY’S UNIFYING THEME • The history of life is a saga of a restless Earth billions of years old – Fossils document this history

Figure 1.10 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• Life evolves – Each species is one twig of a branching tree of life extending back in time Giant Spectacled Sloth panda bear bear

Sun American Asiatic Polar bear black bear black bear bear

Ancestral bear Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Brown bear

Figure 1.11

The Darwinian View of Life • The evolutionary view of life came into focus in 1859 when Charles Darwin published The Origin of Species

Figure 1.12 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• Darwin’s book developed two main points – Descent with modification – Natural selection

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Natural Selection • Darwin was struck by the diversity of animals on the Galápagos Islands • He thought of adaptation to the environment and the origin of new species as closely related processes – As populations separated by a geographic barrier adapted to local environments, they became separate species

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• Fourteen species of Galápagos finches have beak shapes adapted to suit their environments

Cactus ground finch

Medium ground finch

Large ground finch

Small ground finch

Large cactus ground finch

Small tree finch

Vegetarian finch

Medium Woodpecker tree finch finch

Large Mangrove tree finch finch

Gray Green warbler warbler finch finch

Sharp-beaked ground finch

Seed-eaters

Cactus-flower Bud-eater -eaters

Ground finches

Insect-eaters

Tree finches

Common ancestor from South American mainland Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Warbler finches

Figure 1.13

Darwin’s Inescapable Conclusion • Darwin synthesized the concept 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

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• Fact 1: Overproduction and struggle for existence • Fact 2: Individual variation • The inescapable conclusion: Unequal reproductive success – It is this unequal reproductive success that Darwin called natural selection – The product of natural selection is adaptation

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• Natural selection is the mechanism of evolution

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 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 1.14

Observing Artificial Selection • Artificial selection is the selective breeding of domesticated plants and animal by humans

Figure 1.15 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

Observing Natural Selection • There are many examples of natural selection in action – The development of antibiotic-resistant bacteria is one

Figure 1.16 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings

• 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

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