Chapter 1-6

Course Overview and Structure

Course Introduction

This course, based on Campbell Biology, 12th Edition, provides a comprehensive introduction to the foundational concepts of biology. It covers the unifying themes of biology, the scientific method, the chemical context of life, and the properties of water, carbon, and macromolecules. The course is structured around lectures, laboratory work, and active participation, with assessments including exams, quizzes, homework, and lab assignments.

Grading and Participation

• Lecture: 2/3 of total grade (Exams, Participation, Homework)

• Lab: 1/3 of total grade (Assignments, Quizzes, Lab Practical)

• Participation: Includes in-class and at-home activities, often using the iClicker app for engagement.

Unifying Themes of Biology

Introduction to Biology

Biology is the scientific study of life. Biologists investigate questions such as how organisms develop, how the mind works, and how living things interact within communities. Life is recognized by the activities and properties that living things exhibit.

Themes in Biology

Biology is organized around several unifying themes that help structure our understanding of life:

• Organization

• Information

• Energy and Matter

• Interactions

• Evolution

Properties of Life

All living things share several key properties:

• Order

• Evolutionary Adaptation

• Energy Processing

• Growth and Development

• Response to the Environment

• Regulation

• Reproduction

Levels of Biological Organization

Life can be studied at multiple levels, from molecules to the entire biosphere:

• Molecules

• Organelles

• Cells

• Tissues

• Organs

• Organisms

• Populations

• Communities

• Ecosystems

• The Biosphere

Scientific Inquiry

The Scientific Process

The scientific method is an idealized process of inquiry involving observation, hypothesis formation, experimentation, and analysis. In practice, science is iterative, with backtracking and retesting as new data emerge. Collaboration and diverse viewpoints enhance scientific progress.

Evolution: The Core Theme of Biology

Evolution and Diversity

Evolution is the process of change that has transformed life on Earth, accounting for both the unity and diversity of life. Evidence for evolution includes similarities among fossils and living organisms, common cellular processes, and the universal structure of DNA. Taxonomy is the branch of biology that names and classifies species into groups of increasing breadth.

Chemical Context of Life

Elements and Compounds

All organisms are composed of matter, which consists of chemical elements and compounds. An element is a substance that cannot be broken down by chemical reactions, while a compound consists of two or more elements in a fixed ratio.

• About 20-25% of the 92 elements are essential for human life.

• Four elements (O, C, H, N) make up 96% of living matter.

• Trace elements are required in minute quantities.

Chemical Bonds

The formation and function of molecules depend on chemical bonding between atoms:

• Covalent bonds (nonpolar and polar): Atoms share electrons.

• Ionic bonds: Formed between strongly oppositely charged ions.

• Hydrogen bonds: Formed between slightly oppositely charged regions of molecules.

Water and Life

Properties of Water

Water is essential for life, making up 70–95% of most cells. Its unique properties are due to its polarity and ability to form hydrogen bonds:

• Cohesion and Adhesion: Hydrogen bonds hold water molecules together (cohesion) and allow them to adhere to other substances (adhesion).

• High Specific Heat: Water can absorb or release large amounts of heat with little temperature change, stabilizing environments.

• Expansion Upon Freezing: Ice is less dense than liquid water, allowing it to float and insulate aquatic life.

• Versatility as a Solvent: Water dissolves many substances due to its polarity, making it the solvent of life.

Acids, Bases, and Buffers

Acids increase the H+ concentration of a solution, while bases reduce it. Buffers minimize changes in pH, maintaining homeostasis in living organisms. Human activities, such as burning fossil fuels, can disrupt this balance and acidify the oceans.

Carbon and Molecular Diversity

Organic Molecules and Macromolecules

Organic molecules contain carbon, which can form four stable covalent bonds. Macromolecules are large molecules essential for life, built from smaller units called monomers. The four major classes are:

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Polymers are synthesized by dehydration reactions and broken down by hydrolysis.

Summary of Chapters 1-6

• Unifying Themes in Biology

• Chemical Context of Life

• Water: The Molecule of Life

• Carbon & Molecular Diversity

• Macromolecules

• The Cell