Study Notes for General Biology I (BIO 191)
Introduction to BIO 191: General Biology I
This course provides a foundational understanding of biological principles and processes.
What is Life?
Biology: The scientific study of life.
Defies a simple, one-sentence definition.
Life is characterized by the activities and functions of living organisms.
Unifying Themes of Biology
Biology is a vast subject encompassing various themes that unify the study of life.
Five Unifying Themes:
Organization: Life organizes itself from molecules to biosphere.
Genetic Information: Information is hereditary, stored in genes.
Energy & Matter: Biological processes require energy and matter.
Interactions: Interactions among living systems are crucial.
Evolution: The process of change in biological organisms over time.
The Biological Hierarchy
The biological hierarchy represents levels of biological organization:
Biosphere: Global ecological systems integrating all living beings and their relationships.
Ecosystems: Communities of organisms interacting with their environment.
Communities: Different populations living together in a defined area.
Populations: Groups of individuals of the same species within a specific area.
Organisms: Individual living entities.
Organs: Collections of tissues that perform a specific function.
Tissues: Groups of similar cells performing a common function.
Cells: The smallest unit of life that can perform all activities required for life.
Organelles: Specialized structures within cells, e.g., nucleus, mitochondria.
Molecules: The chemical building blocks of all matter.
Reductionism and Emergent Properties
Reductionism: A method of studying biology by breaking down complex systems into simpler components.
Example: Molecular biology.
Emergent Properties: Properties that arise at each level of biological organization that are not present at the lower levels.
Example: Systems biology examines interactions that occur in biological systems.
The Cell: The Smallest Unit of Life
Two Main Forms:
Prokaryotic Cells: Simpler, lack a nucleus.
Eukaryotic Cells: More complex, containing a nucleus and organelles.
Structure & Function
There is a correlation between form and function at all levels of biological hierarchy.
Example: The anatomy of a hummingbird reflects its function in rapid flight and feeding.
Genetic Information
Genetic information is stored in molecules of DNA.
Gene: The unit of inheritance.
Deoxyribonucleic Acid (DNA): Contains genetic instructions for development, functioning, growth, and reproduction.
Structure of DNA:
(a) DNA double helix
(b) Single strand of DNA with nucleotides (A, T, G, C in complementary base pairing).
Life's Processes Involving Genetic Information
Transmitting Information (Inheritance):
Involves the passage of genetic information from parents to offspring through reproductive cells.
Example: Sperm and egg combine to form a fertilized egg, which develops into an embryo with inherited traits.
Expressing Information:
Expression of genes leads to the production of cellular products like proteins.
Central Dogma of Biology: The process of genetic information flow: DNA → RNA → Protein.
Transcription: Conversion of DNA to RNA.
Translation: Synthesis of proteins from RNA.
Energy & Matter
Biological processes require transformation of energy and matter:
Energy Flow: Energy moves through an ecosystem in a linear fashion.
Chemical (Matter) Cycling: Matter is recycled, facilitating continual energy flow and system sustainability.
Energy Flow and Chemical Cycling in Ecosystems
Flow of Energy:
Plants absorb light energy, convert it to chemical energy via photosynthesis, and serve as the foundational energy source in ecosystems.
Decomposers return nutrients to the soil, maintaining the cycle.
Interactions in Biological Systems
Interactions ensure the smooth integration of system components across all levels of the biological hierarchy.
Negative Feedback Regulation:
Example: High blood glucose triggers insulin release, which lowers blood glucose levels, leading to reduced insulin secretion when homeostasis is reached.
Positive Feedback Regulation:
Example: Suckling stimulates oxytocin release, enhancing milk ejection, further encouraging suckling.
Evolution
Charles Darwin's Theory of Evolution:
Introduced in Origin of the Species (1859), emphasizing Natural Selection:
Three Observations:
Species exhibit variations that are heritable.
Overproduction leads to competition for resources.
Species adjust to their environments over time.
Natural Selection Process:
Traits that enhance survival and reproduction are preserved, leading to adaptation.
Descent with Modification:
Indicates that species evolve and diversify from common ancestors, explaining both unity and diversity of life.
Taxonomy and Classification of Life
All life categorized into three major domains:
Bacteria: Prokaryotes, diverse and widespread.
Archaea: Prokaryotes, often living in extreme environments.
Eukarya: Eukaryotes, which include:
Single-celled: Protists.
Multicellular: Plants, fungi, and animals.
Examples of Multicellular Organisms
Plants: Autotrophic; produce their own food through photosynthesis.
Fungi: Heterotrophic; absorb nutrients from their environment.
Animals: Ingest their food and process it internally.
Identification of Organisms
Organisms can be identified by their genus and species names.
Example: American Black Bear is classified as Ursus americanus.
Evolutionary Relationships
Evolutionary trees illustrate relationships among species, showing divergence from common ancestors:
Example: Various finch species derived from a common ancestor adapt to their environments through natural selection.
Evolutionary Timeline
A representation of major events in the history of life on Earth and associated mass extinctions.
The timeline illustrates the rise and fall of species over millions of years, including significant evolutionary advancements.