Introduction to Biology

Why Biology Matters

• Biology provides answers related to the origin, persistence, and changes of life.
• Life has existed for billions of years, originating from nonliving materials assembling into the first organized, living cells.

Characteristics of Living Organisms

• Living organisms share a set of characteristics.
• Living organisms have biological molecules and gather energy and materials.
• Living organisms respond to environmental changes.
• The structure and function of living organisms often change from one generation to the next.
• All matter, including living organisms, is composed of atoms and molecules.

Emergent Properties

• The organization of life extends through multiple levels of a hierarchy.
• Complex biological molecules constitute the lowest level of organization, but they are not alive.
• Emergent properties rely on the level of organization but do not exist at lower levels.
• Life is an emergent property of the organization of cells from matter.

Levels of Organization

• Cells are the basic biological unit that can survive and reproduce.
• Populations are groupings of the same organisms living in the same place.
• A community includes all populations of different organisms in one location.
• An ecosystem encompasses the community and the nonliving environmental factors interacting with it.
• The biosphere includes all ecosystems on Earth, including waters, crust, and the atmosphere.

Genetic Information

• Deoxyribonucleic acid (DNA) is a large, double-stranded, helical structure.
• A living organism's DNA makes up its genome.
• Instructions are copied from DNA into ribonucleic acid (RNA).
• Proteins perform most life activities.

Metabolic Activity

• Metabolism is a cell or organism’s ability to extract surrounding energy.
• Plants perform photosynthesis.
• Most organisms use cellular respiration to break down biological molecules.

Energy Flow and Matter Cycles

• Photosynthetic organisms are primary producers of food for other organisms.
• Animals are consumers.
• Some bacteria and fungi are decomposers.
• Energy from sunlight underpins most life on Earth.
• Photosynthetic organisms trap some sunlight, which flows between organisms and ecosystems.
• Matter cycles between living organisms and nonliving parts of the biosphere.

Environmental Changes: Compensation

• Living organisms can detect and compensate for environmental changes.
• Receptors, varied and diverse, detect changes in external and internal conditions.
• Stimulation causes receptors to initiate reactions.
• Homeostasis is exemplified by the regulation of internal body temperature within a narrow range.
• All organisms have mechanisms for maintaining homeostasis.

Reproduction and Development

• Reproduction is the process of parents passing DNA to offspring.
• The passage of DNA from one generation to another is inheritance.
• Multicellular organisms undergo development.
• The life cycle refers to sequential stages individuals go through.

Biological Evolution

• Populations of all organisms change from one generation to the next, and this process is biological evolution.
• Biological evolution is a fundamental process of life.
• The evolutionary process reveals that all populations change over time, all organisms descend from a common ancestor, and evolution drives the diversity of life.
• Evolution is a unifying theme in biology.

Darwin and Wallace

• Charles Darwin and Alfred Russel Wallace were British naturalists (1800s) who proposed a mechanism for evolution.
• Darwin's observations during a five-year voyage and Wallace's work in South America and Asia supported their conclusions.
• Domesticated animals observations and experiments were used to study evolution
• The name for the equivalent process that happens in the wild is natural selection
• Darwin and Wallace’s observations:
  • Most organisms produce many offspring, but environmental factors limit survival and reproduction.
  • Heritable variations allow some individuals to compete better for resources.
  • Successful individuals pass their characteristics to offspring.
  • Favorable traits increase in future generations.
• Variability among individuals arises through random changes, known as mutations.
• Rock pocket mice (Chaetodipus intermedius) are an example of adaptation.

Tree of Life: Biodiversity

• A species includes populations of individuals with similar structure, biochemistry, behavior and can interbreed.
• A genus is a related group of similar species that have a common ancestor
• Each species has a two-part scientific name, which makes up the binomial nomenclature.
• Species are grouped into classifications:
  • Species > Genus > Family > Order > Class > Phylum > Kingdom.
• Biologists use DNA and other biological molecules to create phylogenetic trees.
• The major trunks on the Tree of Life consist of 3 domains:
  • Bacteria
  • Archaea
  • Eukarya
• Bacteria and Archaea are prokaryotes.
• Eukarya are eukaryotes.

The 3 Domains

• Microscopic unicellular organisms found everywhere on Earth: Domain Bacteria
• Microscopic unicellular organisms that commonly inhabit extreme environments: Domain Archaea
• They are diverse single-celled and multicellular eukaryotic species: Domain Eukarya
• Kingdom Plantae is mostly photosynthetic multicellular organisms
• Kingdom Fungi are decomposers that break down and absorb biological molecules from dead organisms
• Kingdom Animalia are multicellular consumers that actively move from one place to another

Biological Research Types

• Biological research includes trying to understand diverse aspects of the living world.
• Basic research seeks theoretical explanations of natural phenomena.
• Applied research aims to solve problems like drug development.

The Scientific Method

• The scientific method is an investigative approach to getting knowledge.
• Scientists observe the natural world, make working explanations (hypotheses), and test predictions by collecting data
• Scientists then share results via publications, enabling repeats and verification.
• Scientific research is descriptive or experimental:
  • Observational data gives basic info/details of biological processes and systems.
  • Experimental data is the result of manipulation and answers how/why systems work.

Testing Hypotheses

• Scientists make tentative explanations (hypotheses) after facts are observed.
• A null hypothesis states what would be seen if the tested hypothesis is wrong.
• A scientific hypothesis must be falsifiable through testing, and should explain the relationship between variables.
• Hypotheses must yield the testable predictions of what to expect of one variable changes is another changes
• Scientists must test the predictions and the hypotheses, generating data
• The hypothesis must be modified if data refutes it, but no data proves that a hypothesis is correct
• Data can support/confirm hypotheses.
• Experimental or observational with null hypotheses are ways to evaluate data and systems.
• Molecular tools help researchers explore genomic, bioinformatic and proteomic data to help build a Tree of Life
• Genomics is characterizing entire genomes.
• Proteomics studies the proteome, which changes in response to the environment, unlike the stable genome
• Bioinformatics tools analyze the data gathered from projects.
• Scientific theories stem from repeated testing, addresses many questions, and scientific theories are very unlikely to be contradicted by future discoveries.
• Motivations: Curiosity, practical applications, and honesty.