• Matthias Schleiden observed that all plants were made of cells; Theodor Schwann observed that all animals were also made of cells; and Rudolf Virchow observed that cells only come from other cells.
• Prokaryotic cells- don’t contain a nucleus or any other membrane-bound organelle.
Eukaryotic cells- contain membrane-bound organelles, including a nucleus.
• Phospholipids make up the basic structure of a cell membrane and are arranged in a double layer called the lipid bilayer.
• Active Transport- moves ions from low concentration to high, using metabolic energy in the form of ATP.
Passive Transport - moves ions from high concentration to low, using no metabolic energy.