Topic 1 Introduction to the Study of Life 1.1 The Unifying Characteristics of Life Biology 1001 September 9, 2005

Why Study Biology? Rooted in the human spirit Curiosity, recreation, enjoyment of nature Our connectedness to living things Conservation of biodiversity important  E. O. Wilson’s biophilia

Why is Biology Important? Woven into the fabric of society - Health and disease - Nutrition - Agriculture - Management of natural resources Applicable in diverse disciplines - Psychology, sociology, criminal science - Even architecture!

Life Is A Myriad of Diverse Forms

So How Do We Recognize Life? Unifying Properties & Processes Characterize Living Things Order Evolutionary adaptations  Cells as the basic unit of structure  DNA as the hereditary material The study of life has both horizontal and vertical dimensions! Response to environment Reproduction Energy processing Growth and development Regulation and homeostasis

Figure 1.2 Some properties of life (c) Response to the environment (a) Order (d) Regulation (g) Reproduction (f) Growth and development (b) Evolutionary adaptation (e) Energy processing

Examples – Order & Energy Utilization

Examples – Reproduction, Growth & Development

A Hierarchy of Biological Organization The study of life –Extends from the microscope scale of molecules and cells to the global scale of the entire living planet The hierarchy of life –Extends through many levels of biological organization The challenge is integration across dimensions!

Figure 1.3 Exploring Levels of Biological Organization 1 The biosphere 2 Ecosystems 3 Communities 4 Populations 5 Organisms

8 Cells 6 Organs and organ systems 7 Tissues 10 Molecules 9 Organelles 50 µm 10 µm 1 µm Cell Atoms

Cells A diversity of cell form!

The cell –Is the lowest level of organization that can perform all activities required for life All cells share certain characteristics –They are all enclosed by a membrane –They all use DNA as genetic information –They all contain a cellular fluid and ribosomes There are two main forms of cells –Eukaryotic –Prokaryotic Cells

Pro=first, eu=true, karyon=nucleus Eukaryotic cells –Are subdivided by internal membranes into various membrane- enclosed organelles –Nucleus, mitochondria, chloroplasts –All other organisms Prokaryotic cells –Lack the kinds of membrane-enclosed organelles found in eukaryotic cells –Are smaller than eukaryotic cells –Prokaryotes Prokaryotic Vs. Eukaryotic Cells

EUKARYOTIC CELL Membrane Cytoplasm Organelles Nucleus (contains DNA) 1 µm PROKARYOTIC CELL DNA (no nucleus) Membrane Figure 1.8

DNA - The Cell’s Heritable Information Cells contain chromosomes made partly of DNA, the substance of genes –Which program the cells’ production of proteins and transmit information from parents to offspring Egg cell Sperm cell Nuclei containing DNA Fertilized egg with DNA from both parents Embyro’s cells with copies of inherited DNA Offspring with traits inherited from both parents

The molecular structure of DNA accounts for its information-rich nature DNA Cell Nucleotide A C T A T A C C G G T A T A (b) Single strand of DNA. These geometric shapes and letters are simple symbols for the nucleotides in a small section of one chain of a DNA molecule. Genetic information is encoded in specific sequences of the four types of nucleotides (their names are abbreviated here as A, T, C, and G). (a) DNA double helix. This model shows each atom in a segment of DNA.Made up of two long chains of building blocks called nucleotides, a DNA molecule takes the three-dimensional form of a double helix. Nucleus

Feedback Regulation in Biological Systems A “supply-and- demand” feature regulates some of the dynamics of living systems The output, or product, of a process regulates that very process Feedback can be Negative or Positive

In negative feedback An accumulation of an end product slows the process that produces that product

In positive feedback The end product speeds up production

The Emergent Properties of Biological Systems A system is a combination of components that form a more complex organization Biological systems are much more than “the sum of their parts” New properties emerge with each step upward in the hierarchy of biological organization

Examples of Emergent Properties Non-Living Examples Graphite vs. diamond  NaCl A hammer Biological Examples Ecosystems Feedback regulation Consciousness Photosynthesis Enzymes & other proteins 

Systems Biology Systems biology seeks to create models of the dynamic behavior of whole biological systems With such models scientists will be able to predict how a change in one part of a system will affect the rest of the system Is now taking hold in the study of life at the cellular and molecular levels Includes three key research developments: high-throughput technology, bioinformatics, and interdisciplinary research teams

Examples of Systems Biology 2. A systems map of interactions between proteins in a cell 1. The “greenhouse effect” 3. The Human Genome ProjectThe Human Genome Project

Correlation Between Structure and Function at All Levels of Biological Organization