Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

The Golgi apparatus is responsible for sorting and distributing proteins within the cell. Once proteins are synthesized in the rough endoplasmic reticulum, they are transported to the Golgi apparatus, where they undergo further processing. This includes modifications such as glycosylation (adding sugar molecules) and phosphorylation (adding phosphate groups). The Golgi apparatus then packages these modified proteins into vesicles that are directed to their designated locations, whether that be inside the cell, in the cell membrane, or for secretion outside the cell. This organelle plays a crucial role in ensuring that proteins reach the correct destination, thus facilitating proper cell function.

The nucleus is primarily involved in storing and transmitting genetic information, while lysosomes are responsible for breaking down waste materials and cellular debris. Ribosomes are the sites of protein synthesis, where amino acids are assembled into proteins based on the instructions carried by messenger RNA. Thus, the unique role of the Golgi apparatus in protein processing and distribution distinguishes it as the correct answer.