1.1 Cell theory

Four tenets of cell theory:

1. All living things composed of cells
2. Cell is basic functional unit of life
3. Cells arise only from preexisting cells
4. Cells carry genetic information in the form of DNA (deoxyribonucleic acid), genetic material is passed on from parent to daughter cell

• Viruses are not considered living organisms because they violate 3rd & 4th cell theory (can only replicate by invading other organisms & may use RNA instead of DNA as genetic information)

[High Yield] 1.2 Eukaryotic cells

• Prokaryotic organisms—always single celled
  • Do not contain nucleus
• Eukaryotic organisms—can be unicellular or multicellular
  • Contain true nucleus enclosed in membrane

Membrane-Bound Organelles

• In eukaryotic cells, most organelles are membrane bound, allowing for compartmentalization
• Organelles are suspended in a semifluid cytosol
• Membranes of eukaryotic cells consist of a phospholipid bilayer
  • Surface hydrophilic, electrostatically interacting with aqueous environment inside & outside of cell
  • Inner hydrophobic, provide highly selective barrier between interior of cell & external environment

The Nucleus

• Contains all genetic material necessary for the replication of the cell
• Surrounded by nuclear membrane/envelope—double membrane that maintains nuclear environment separate from cytosol
• Nuclear pores—allow selective 2 way exchange of material between cytoplasm and nucleus
  • Compartmentalization allows DNA transcription to be separate from RNA translation