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Chapter 1: Evolution, the Themes of Biology, and Scientific Inquiry

Introduction to Biology

• Biology is the scientific study of life.

• Recognizes life through the activities of living organisms.

• Biology is a subject of enormous scope.

• Taxonomy: study of biological names

Unifying Themes in Biology

• Five unifying themes:

  • Organization: Life is structured hierarchically.

  • Information: Genetic information guides development and functioning.

  • Energy and Matter: Life relies on energy transformation.

  • Interactions: Interactions shape ecosystems and biological processes.

  • Evolution: Explains the unity and diversity of life.

Properties of Life

• Key characteristics include:

  • Order: Organized structures of living organisms.

  • Regulation: Homeostasis and regulation of internal environments.

  • Reproduction: Ability to reproduce and pass on genetic information.

  • Adaptation: Adjustments to environmental changes over generations.

  • Response to Environment: Organisms react to stimuli from their surroundings.

  • Energy Processing: Utilization of energy for growth and survival.

Biological Organization

• Life can be studied at various levels:

  • Molecules, Cells, Tissues, Organs, Organisms, Populations, Communities, Ecosystems, Biosphere.

• Reductionism: Breaking complex systems into simpler parts for study.

Emergent Properties

• Result from the arrangement and interactions of components.

• Nonbiological examples, like bicycles, illustrate emergent properties.

• Systems biology examines interactions among biological system parts.

• Can be used to study life at all levels.

Structure and Function

• At each level of the biological hierarchy we find a correlation between structure and function.

The Cell

• Basic unit of structure and function in life.

• Smallest unit of organization that perform all activities required for life.

• Cell Theory: All living organisms are composed of cells.

• Two types:

  • Prokaryotic: Simple, no nucleus (e.g., bacteria and archaea).

  • Eukaryotic: Complex, membrane-enclosed organelles, with nucleus (e.g., plants, animals).

Genetic Information

• Chromosomes contain DNA, the genetic material.

• DNA (deoxyribonucleic acid)

• DNA holds genes that encode for proteins and direct development.

• Genes: the units of inheritance.

• Made up of two long chains arranged in a double helix; each chain made up of four kinds of chemical building blocks called nucleotides and abbreviated A, C, G, T.

• A: adenine

• C: cytosine

• G: guanine

• T: thymine

• (A+T) (G+C)

• Gene expression: the process of converting information from gene to cellular product.

Genomics and Proteomics

• Genomics: Study of entire genetic sequences.

• Genome: entire “library” of genetic instructions.

• Proteomics: Analysis of whole sets of proteins in organisms.

• Proteome: the entire set of proteins expressed by a given cell, tissue, or organ.

• Bioinformatics: the use of computational tools to process a large volume of data very rapidly.

Energy and Matter Transfer

• Energy input from the sun drives life processes.

• Photosynthetic organisms convert solar energy into chemical energy.

• Energy flows through ecosystems; chemicals cycle among organisms.

Interactions in Biological Systems

• Essential for organism function and ecosystem stability.

• Feedback mechanisms (negative and positive) regulate biological processes.

• Feedback regulation: the output, or product of a process, regulates that very process.

Ecosystem Interactions

• Organisms interact with each other and their physical environment.

• Human impacts contribute to climate change and habitat loss.

Core Theme: Evolution

• Key unifying concept explaining diversity of life.

• Understanding of evolution aids in comprehending biological relationships.

• Natural Selection: Mechanism through which evolution occurs.

Classification of Life

• Approximately 1.8 million species identified.

• Each species is given a two-part name: The genus, to which the species belongs, and a species name unique to that species. (e.g., Homo sapiens)

• Organisms classified into three domains:

  • Bacteria, Archaea, Eukarya.

• Eukarya includes the four subgroups:

  • Plants; which produce their own food by photosynthesis.

  • Fungi; which absorb nutrients.

  • Animals; which ingest their food.

  • Protists; which can either consume or produce their foods.

Darwin and Evolution

• On the Origin of Species by Means of Natural Selection (1859).

• Introduced natural selection as a driving force behind adaptation.

• He made two points:

  • Species showed evidence of “descent with modification” from common ancestors.

  • “Natural Selection” is the mechanism behind descent with modification.

• Observed variations in traits and implications for species survival.

Scientific Inquiry

• Science is a process of inquiry involving observation and hypothesis testing.

• The word science is derived from Latin and means “to know”.

• Methods include gathering data, forming and testing hypotheses, and utilizing inductive and deductive reasoning.

• Controlled experiment: an experimental group is compared with a control group.

• Independent variable: the one that is manipulated by the researchers.

• Dependent variable: the one predicted to be affected in response.