Cellular Anatomy

Cell Structure

Cell membrane

composed of a phospholipid bilayer and various proteins

act to enclose cell and regulate passage of substances

membrane permeability depends on integral and carrier proteins, lipid solubility, molecular size and ionic charge


80% to 90% water plus various electrolytes



extensions of cytoplasm containing microtubules

secrete mucous and move


membrane specializations that increase surface area


bounded by a double walled membrane with pores

contain Chromatin - protein and DNA

contains the Nucleolus - protein and RNA


free of or attached to ER; composed of protein and RNA

Endoplasmic reticulum (ER)

consists of interconnected membranes, and tubules between the membranes, that connect to the nucleus

act as transportation pathways and storage sites

Rough ER - ribosomes on membranes, synthesize proteins

Smooth ER - no ribosomes, synthesize lipids

Golgi apparatus

consists of membranous sacs continuous with ER

synthesize carbohydrate compounds

acts in cellular secretion thru production of Vesicles


consist of a sac like double membrane (cristae)

site for cellular energy production


vesicles containing digestive enzymes; common in phagocytic cells


vesicles containing enzymes that produce (and breakdown) hydrogen peroxide

Fibrils and Microtubules

act as a cytoskeleton

fibrils are specialized in muscle for contraction (Myofibrils

microtubules transport macromolecules


9 evenly spaced bundles of 3 microtubules per bundle

act in separation of chromatids during cell division


David G. Ward, Ph.D.  Last modified by wardd 23 May, 2006