Write the main function of each of the following.

The plasma membrane functions as a selectively permeable barrier controlling the exchange of materials between the cell and its environment, while also facilitating cell recognition, communication, and maintaining cellular integrity through receptor proteins and structural support.

The cell wall provides rigid structural support and protection to plant cells, maintains cell shape, prevents excessive water uptake and bursting in hypotonic conditions, and acts as a defensive barrier against mechanical stress and pathogen invasion.

Ribosomes are the sites of protein synthesis, where they translate genetic information from mRNA into polypeptide chains by linking amino acids in the sequence specified by the genetic code—a fundamental process for all cellular functions.

Lysosomes serve as the cell's digestive system, containing hydrolytic enzymes that break down worn-out organelles, cellular debris, and foreign materials, essentially functioning as waste disposal units and recycling centers that maintain cellular health.

The nucleolus, located within the nucleus, is primarily responsible for ribosomal RNA (rRNA) synthesis and ribosome assembly, producing the cellular machinery necessary for protein production throughout the cell.

The endoplasmic reticulum functions as an extensive network for protein and lipid synthesis, modification, and transport; the rough ER (studded with ribosomes) synthesizes and processes proteins for secretion, while the smooth ER produces lipids, detoxifies harmful substances, and stores calcium ions.