Introduction to Biology

What is Biology?

• Biology is the scientific study of life.
• Examples of questions asked in biology include how a single cell develops into an organism, how living things interact in communities, and how living things can be manipulated to benefit humans.
• This lecture covers the naming of organisms.
• Lecture 2 covers the scientific method in studying life.
• Lectures 3 & 4 introduce the theory of evolution.

Being Alive

• Life is recognized by what living things do.
• Living things have seven unique features that separate them from non-living things.

Characteristics of Living Organisms

• Ordered structure is a key characteristic of living organisms, who maintain an internal order with the cell being the simplest unit of organization.
• Energy processing and metabolism is essential to maintain internal order, organisms need energy, which is utilized in chemical reactions known as metabolism.
• A key characteristic is responding to environmental changes, and promote survival.
• Regulation and homeostasis, is regulating cells and bodies to maintain relatively stable internal conditions.
• Growth and development is where growth produces more or larger cells and development produces organisms with a defined set of characteristics.
• Reproduction is key to sustain life over many generations where genetic material causes offspring to have traits like their parents.
• Biological evolution and adaptation is where populations of organisms change over generations, with evolution resulting in traits for survival and reproductive success.

Levels of Biological Organization

• Biology studies life from microscopic components to the scale of the entire planet.
• Life can be studied at different levels from molecules to the entire living planet.
• Molecules such as carbohydrates, proteins, and DNA, fall under molecular biology and biochemistry.
• Individual cells like muscle and nerve cells studies are cell biology.
• Tissues, organs, and whole organisms fall under anatomy, physiology, and taxonomy.
• Interactions between organisms and their environment is ecology.
• All levels of biological organization fall under evolutionary biology.

Organizing the Diversity of Life

• Approximately 1.8 million species have been identified and named to date.
• Thousands more species are identified each year.
• Estimates of the total number of species range from 10 million to over 100 million.
• Life is arranged into hierarchical groups based on similarity and relatedness.
• Domains followed by kingdoms are the broadest units of classification.

The Three Domains of Life

• All life forms are classified into one of three domains: Bacteria, Archaea, and Eukarya.
• Bacteria and Archaea are prokaryotes.
• Domain Eukarya includes all eukaryotic organisms, including all plants and animals.
• Prokaryotes often live in extreme environments.
• The domain Eukarya includes the multicellular kingdoms: Plantae, Fungi, and Animalia.
• Eukaryotic organisms were formerly grouped into a kingdom called Protista, but are now often grouped into many separate kingdoms.

Taxonomy

• Taxonomy is the branch of biology that names and classifies species into groups.
• Carl Linnaeus introduced the binomial Latin name (genus and species).
• A system for naming organisms is still in wide use today.
• Scientific names are the genus followed by the species, in italics or underlined
• For example, Felis catus which is as domestic cat

Unity in Diversity

• A striking unity underlies the diversity of life.
• DNA is the universal genetic language common to all organisms.
• Unity is evident in many features of cell structure.