Chapter 1: Evolution & The Foundations of Biology – Study Notes

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Chapter 1: Evolution & The Foundations of Biology

Introduction

This chapter introduces the fundamental concepts of biology, focusing on the unifying themes of life, the structure and function of cells, the organization of biological systems, and the principles of evolution. Understanding these foundations is essential for further study in biology.

Cell Theory and Types of Cells

The Cell as the Basic Unit of Life

Cell: The smallest unit of life that can carry out all life processes. All living organisms are composed of one or more cells.
Types of Cells:
- Eukaryotic cells: Have a nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).
- Prokaryotic cells: Lack a nucleus and most organelles (e.g., bacteria, archaea).
- Viruses: Non-cellular entities that require a host cell to reproduce; not considered living by most definitions.
Key Characteristics: All cells have a plasma membrane, cytoplasm, genetic material (DNA or RNA), and ribosomes.

Levels of Biological Organization

From Atoms to Biosphere

Biological systems are organized in a hierarchy from smallest to largest:

Atom
Molecule
Organelle
Cell
Tissue
Organ
Organ system
Organism
Population
Community
Ecosystem
Biosphere

Each level builds upon the previous, increasing in complexity.

Genetic Information and DNA

Genes and the Unity of Life

DNA (Deoxyribonucleic Acid): The molecule that stores genetic information in all living organisms.
Genes: Segments of DNA that code for proteins or functional RNA molecules.
DNA provides the instructions for the structure, function, and regulation of an organism's cells, tissues, and organs.
Genetic information is passed from parent to offspring, ensuring continuity of life.

Metabolism and Energy Flow

Metabolism and Nutrient Cycling

Metabolism: The sum of all chemical reactions that occur within an organism to maintain life.
Metabolism includes catabolism (breaking down molecules to release energy) and anabolism (building up molecules using energy).
Energy flows one-way through ecosystems, typically entering as sunlight and leaving as heat, while nutrients cycle within the ecosystem.
Example: Photosynthesis in plants converts solar energy into chemical energy, which is then used by other organisms.

Interactions and Responses in Biology

Life Interacting with Environment

Organisms interact with each other and their environment at all levels, from molecules to ecosystems.
These interactions can be cooperative, competitive, or neutral, and they drive the dynamics of populations and communities.
Responses to the environment include movement, growth, adaptation, and changes in behavior or physiology.

Evolution as a Core Theme

Definition and Importance

Evolution: The process by which populations of organisms change over generations through variations in genetic material and natural selection.
Explains the unity and diversity of life, as all organisms share a common ancestry but have adapted to different environments.
Shared characteristics among species are evidence of common descent.
Example: The forelimbs of humans, whales, and bats have different functions but similar bone structures, indicating a common ancestor.

Classification and Domains of Life

Domains and Kingdoms

Life is classified into three major domains:
- Bacteria
- Archaea
- Eukarya
Eukarya includes kingdoms such as Animalia, Plantae, Fungi, and Protista.
Classification hierarchy: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species.
Organisms are named using binomial nomenclature: Genus species (e.g., Homo sapiens).

Mutation, Natural Selection, and Evolutionary Change

Mechanisms of Evolution

Mutation: Random changes in DNA sequence that can introduce new genetic variation.
Natural Selection: The process by which individuals with advantageous traits survive and reproduce more successfully, leading to adaptation.
Mutation is random; natural selection is non-random and leads to adaptation.
Other mechanisms include genetic drift, gene flow, and sexual selection.

Evolution in Action and Selection Forces

Contemporary Evolutionary Processes

Evolution can be observed within human lifetimes, such as the development of antibiotic resistance in bacteria or pesticide resistance in insects.
Selection forces include environmental changes, disease, and human interventions.
Understanding these processes helps in managing health, agriculture, and conservation.

Key Vocabulary

Term	Definition
Biosphere	The global sum of all ecosystems; the zone of life on Earth.
Cell	The basic structural and functional unit of all living organisms.
Community	All the populations of different species living and interacting in a particular area.
DNA	Deoxyribonucleic acid, the molecule that carries genetic information.
Ecosystem	A community of organisms and their physical environment interacting as a system.
Evolution	The process of change in populations over time through genetic variation and natural selection.
Genes	Units of heredity made up of DNA.
Genetic Variation	Differences in DNA sequences among individuals in a population.
Kingdom	A major taxonomic category, below domain and above phylum.
Metabolism	All chemical reactions that occur within an organism.
Mutation	A change in the DNA sequence.
Natural Selection	The process by which organisms better adapted to their environment tend to survive and produce more offspring.
Nucleus	Membrane-bound organelle in eukaryotic cells that contains genetic material.
Organ	A group of tissues that work together to perform a specific function.
Organism	An individual living thing.
Population	All individuals of a species living in a specific area.
Prokaryote	Organism without a nucleus (bacteria and archaea).
Species	A group of organisms that can interbreed and produce fertile offspring.
Tissue	A group of similar cells that perform a specific function.

Key Equations

Hardy-Weinberg Equation (for population genetics):

Where p and q are the frequencies of two alleles in a population.

Summary Table: Domains and Key Characteristics

Domain	Cell Type	Example Organisms
Bacteria	Prokaryotic	Escherichia coli
Archaea	Prokaryotic	Halophiles, Thermophiles
Eukarya	Eukaryotic	Plants, Animals, Fungi, Protists