Biology Themes and Chemical Foundations

Major Themes • Organization: Life is hierarchical — molecules → organelles → cells → tissues

→ organs → organisms → populations → ecosystems → biosphere. • Emergent properties:

New properties arise at each level due to increasing complexity. • Cells:

o Prokaryotic: no nucleus, smaller, simpler. o Eukaryotic: nucleus,

membrane-bound organelles. • Genetic Information: o DNA stores hereditary info. o Gene expression:

DNA → RNA → protein. • Energy & Matter: o Energy flows (sun → producers → consumers). o Matter cycles

(nutrients reused). • Interactions: Organisms interact with environment and each other.

• Evolution: o Explains unity & diversity. o Natural selection is the mechanism.