Compound Building Blocks Functions Examples Carbohydrates Simple sugar Provide energy, cell structure Glucose, starch Lipids Glycerol, fatty acids Provide energy, cell structure Triglycerides, phospholipids, steroids Proteins Amino Acids Provide cell structure, enzymes, energy Albumins, hemoglobin Nucleic Acids Nucleotides Store information for the synthesis of proteins, control cell activities RNA, DNA Organelle Structure Function Cell membrane Membrane mainly composed of protein and lipid molecules Maintains integrity of the cell, controls the passage of materials into and out of the cell, and provides for signal transduction. Ribosomes Particles composed of protein and RNA molecules Synthesize proteins Golgi apparatus Group of flattened, membranous sacs Packages and modifies protein molecules for transport and secretion Nucleolus Dense, nonmembranous body composed of protein and RNA molecules Site of ribosome formation Chromatin Fibers composed of protein and DNA molecules Contains cellular information for synthesizing proteins