Hierarchy of Life Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Chapter 1 An Introduction to Biology Key Concepts: 1.1 Principles of Biology and the Levels of Biological Organization 1.2 Unity and Diversity of Life

Biology: the scientific study of living things. 1.1 Principles of Biology Biology: the scientific study of living things. Cells are the simplest units of life Living organisms use energy Living organisms interact with their environment

Principles of Biology Living organisms maintain homeostasis Living organisms grow and develop The genetic material provides a blueprint for reproduction

Principles of Biology Populations of organisms evolve from one generation to the next All species (past and present) are related by an evolutionary history Structure determines function

Principles of Biology New properties of life emerge from complex interactions Biology is an experimental science Biology affects our society

Levels of Biological Organization 1 2 3 4 5 6 7 8 9 Atoms Molecules and macromolecules Cells Tissues Organs Organism Population Community Biosphere Ecosystem 10

1.2 Unity and Diversity of Life All life displays a common set of characteristics United by a shared evolutionary history Diversity Life has a diversity of form in diverse environments

Evolutionary History Life began on Earth as primitive cells between 3.5 - 4 billion years ago (bya) Those primitive cells underwent evolutionary changes to give rise to the species of today Evolutionary history helps us understand the structure and function of an organism

Evolutionary change involves modifications of pre-existing characteristics Structures may be modified to serve new purposes Example: Walking limbs were modified into a dolphin’s flipper or a bat’s wing

Two Mechanisms of Evolutionary Change Vertical descent with modification Progression of changes in a lineage New species evolve from pre-existing species by the accumulation of mutations Natural selection takes advantage of beneficial mutations

Vertical Evolution: The Horse Lineage 5 Millions of years ago (mya) 20 40 55 10 Equus Styohipparion Neohipparion Hipparion Nannippus Hippidium and other genera Pliohippus Calippus Merychippus Archaeohippus Hypohippus Megahippus Sinohippus Anchitherium Parahippus Epihippus Miohippus Mesohippus Paleotherium Propalaeotherium Pachynolophus Orohippus Hyracotherium

Horizontal gene transfer Genetic exchange between different species Relatively rare Genes that confer antibiotic resistance are sometimes transferred between different bacteria species

Horizontal Gene Transfer: Antibiotic Resistance Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Antibiotic- resistance gene DNA Antibiotic- resistance gene from E. coli Bacterial species such as Streptococcus pneumoniae Escherichia coli Horizontal transfer to another species

Tree or web of life? Horizontal gene transfer was an important part of the process that gave rise to modern species Tree of life focuses on vertical evolution The tree of life is predictive Placement of a new species on the tree of life immediately informs us about its biology Understanding relationships among species allows biologists to make predictions about species that have not yet been studied Web of life includes the contribution of horizontal gene transfer

Web of Life: Vertical Evolution and Horizontal Gene Transfer KEY Vertical evolution Horizontal gene transfer Common ancestral community of primitive cells Bacteria Archaea Fungi Animals Eukarya Plants Protists

Classification Taxonomy is the grouping of species based on common ancestry Three domains of life Bacteria - unicellular prokaryote Archaea - unicellular prokaryote Eukarya - unicellular and multicellular eukaryotes Complex cells with a nucleus and organelles Four kingdoms: Protista, Plantae, Fungi, and Animalia

Domain Bacteria: Mostly unicellular prokaryotes that Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Domain Bacteria: Mostly unicellular prokaryotes that inhabit many diverse environments on Earth Domain Archaea: Unicellular prokaryotes that often live in extreme environments, such as hot springs © Dr. David M. Phillips/Visuals Unlimited

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protists Plants Fungi Animals 1: © Dr. Dennis Kunkel/ Visuals Unlimited; 2: © Kent Foster/Photo Researchers; 3: © Carl Schmidt-uchs/Photo Researchers; 4: © Fritz Polking/Visuals Unlimited Domain Eukarya: Unicellular and multicellular organisms having cells with internal compartments that serve various functions

Classification A species is placed into progressively smaller groups that are more closely related Emphasizes the unity and diversity of different species Example: Clownfish

Examples Domain Kingdom Phylum Class Order Family Genus Species Eukarya Animalia Chordata Actinopterygii Perciformes Pomacentridae Amphiprion ocellaris 2,000 mya 600 mya 525 mya 420 mya 80 mya ~ 40 mya ~ 9 mya > 3 mya > 5,000,000 > 1,000,000 50,000 30,000 7,000 360 28 1 Taxonomic group Clown anemonefish is found in Approximate time when the common ancestor for this group arose Approximate number of modern species in this group

Binomial nomenclature Each species has a unique scientific name Genus name capitalized Species descriptor is not capitalized Both names are italicized Amphiprion ocellaris = Clownfish

Genomes and Proteomes Genome - the complete genetic makeup of an organism Genomics - techniques used to analyze DNA sequences Comparison of genomes of different species Proteome - the complete complement of proteins of an organism Proteomics - Comparison of proteomes of different species Techniques used to analyze the proteins of a species The study of genomes and proteomes provides an evolutionary foundation for our understanding of biology Fundamental to understanding an organisms characteristics

In eukaryotes, most of the genome is contained within chromosomes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. In eukaryotes, most of the genome is contained within chromosomes that are located in the cell nucleus Gene (a) The genome Most genes encode mRNAs that contain the information to make proteins Cytoplasm Chromosome Chromosome DNA Sets of chromosomes Sets of chromosomes Cell signaling: Proteins are needed for cell signaling with other cells and with the environment Nucleus Nucleus Cytoskeleton: Proteins are involved in cell shape and movement Cell organization: Proteins organize the components within cells Enzymes: Proteins function as enzymes to synthesize and break down cellular molecules and macromolecules Transport proteins: Proteins facilitate the uptake and export of substances Extracellular proteins: Proteins hold cells together in tissues Extracellular fluid (b) The proteome