This preview shows page 1. Sign up to view the full content.
Unformatted text preview: X smaller; no organelles; DNA free in cytoplasm (no nucleus); unicellular types DNA is the Molecule of Life
• DNA contains the information, organized into genes, that determines and controls all functions of an organism. • DNA is the heritable material passed from parent to offspring & directs development of the an organism. • Different RNA molecules serve to convert the information in genes to proteins.
– DNA is the blueprint, proteins are the tools, RNA forms the tools (proteins); proteins have a variety of different functions • The process of transcription generates RNA copies of genes(DNA) & translation deciphers the genetic code to form a specific sequence of amino acids – linked together to form a protein. • The information in genes resides in the sequence of the 4 chemical building blocks (nucleotides) of DNA: adenine, guanine, cytosine, thymine • DNA & the process by which this information is converted to proteins is universal to all life. Biological Systems Are Regulated By Feedback Mechanisms • Organisms detect environmental changes and respond accordingly; attempt to maintain constant internal conditions (homeostasis). • Negative feedback acts to bring a process that is out of range back to homeostasis by reducing its output.
Control of body temperature • Positive feedback: increase the output (speed up production) • Such regulation occurs at all biological levels. Evolution is the Unifying Concept of Biology
• The diversity & unity of life are explained by evolution; current species are the modified descendants of common ancestors. • Rabbit, hummingbird, crocodile, penguin, & seahorse share similar skeletal features (unity), yet have unique differences (adaptations) that suit each to its environment (diversity) • Heritable changes over generations & molded by nature account for these differences. • What is the mechanism for evolutionary change? • Darwin’s concept of change (descent with modification) was based...
View Full Document
- Spring '10