Unit 2: Cell Structure and Function

Ribosomal RNA (rRNA) plus proteins; all life synthesizes proteins, so ribosomes are universal evidence of common ancestry.

Free ribosomes in the cytosol make proteins that stay in the cytosol; bound ribosomes on rough ER make proteins for membranes, lysosomes, or secretion.

It synthesizes and folds proteins for secretion or membranes, and packages them into transport vesicles bound for the Golgi.

Lipid (including steroid) synthesis, detoxification of drugs and poisons, carbohydrate metabolism, and Ca2+ storage (e.g., in muscle cells).

It modifies them (e.g., adding or trimming carbohydrates), sorts them, and packages them into vesicles for their destinations.

It houses most of the cell's DNA as chromatin and is enclosed by a double-membrane nuclear envelope perforated by nuclear pores that control traffic of RNA and proteins.