Lipids and proteins are synthesized in the ____.

A) nucleus
B) mitochondria
C) endomembrane system
D) cytoskeleton
E) cell membrane

Lipids and proteins are synthesized within the endoplasmic reticulum and Golgi apparatus, which are both part of the endomembrane system. The nucleus contains DNA and is responsible for the synthesis of RNA, but not lipids or proteins. The mitochondria are responsible for energy conversion, but not protein or lipid synthesis. The cytoskeleton is responsible for maintaining cell structure and shape, but not protein or lipid synthesis. The cell membrane is responsible for regulating transport in and out of the cell, but not protein or lipid synthesis.