Introduction to Biology: Genetic Information, Energy Flow, Evolution, and Scientific Inquiry
- Chromosomes contain long DNA molecules carrying hundreds or thousands of genes that direct cellular synthesis and development.
- DNA consists of two long chains arranged in a double helix, composed of four nucleotide building blocks abbreviated as A, T, C, and G.
- Gene expression converts genetic information into functional cellular products: DNA is transcribed into mRNA, translated into a sequence of amino acids, and folded into specific functional proteins such as crystallin.
Energy Flow and Matter Cycling
- Energy flows through an ecosystem in a one-way path, entering as sunlight, being transformed into chemical energy by photosynthetic producers, used by consumers to do work, and ultimately exiting as heat.
- Chemical nutrients cycle continuously within an ecosystem between organisms, decomposers, soil, and air.
Diversity and Evolution of Life
- Evolution, defined as descent with modification from common ancestors, accounts for both the unity and diversity of living organisms.
- Organisms are classified into three domains: Bacteria, Archaea, and Eukarya (which includes Kingdom Plantae, Kingdom Fungi, Kingdom Animalia, and Protists).
- In 1859, Charles Darwin published On the Origin of Species, setting forth natural selection as the driving mechanism behind descent with modification.
- Natural selection operates when environmental factors select for individuals with heritable traits best suited to their environment, leading to increased survival, reproduction, and frequency of those advantageous traits over time.
The Process of Scientific Inquiry
- The scientific process is a flexible, iterative framework that rarely follows a rigid linear path and frequently requires backtracking.
- Core components of scientific inquiry involve forming and testing hypotheses, exploration and discovery, community analysis and feedback, and societal outcomes.
