1. Ancestral Protists Larger size Cellular organelles internal structures that carried out specific functions An evolutionary innovation that appeared for the first time in protists Probably formed by fusion of folds of the plasma membrane Incorporated proteins that controlled the movement of molecules into and out of the nucleus Extended outward from the nucleus to form a folded membrane called the endoplasmic reticulum The larger size is the first thing you notice about these fossil cells, but the internal changes in the cells are even more significant because they are the basis for the success of the entire eukaryote lineage, including humans. For the first time in the history of life, cells had internal structures that carried out specific functions. These structures are called cellular organelles, and the specialized activities that these intracellular organelles perform make eukaryote cells more complex than prokaryotes. The larger size is the first thing you notice about these fossil cells, but the internal changes in the cells are even more significant because they are the basis for the success of the entire eukaryote lineage, including humans. For the first time in the history of life, cells had internal structures that carried out specific functions. These structures are called cellular organelles, and the specialized activities that these intracellular organelles perform make eukaryote cells more complex than prokaryotes.

2. Protist Diversity