Introduction 
DNA 
mRNA 
RNA POLYMERASE 
FORMING 
PROTEIN CHAIN 
FORMING 
PROTEIN 
Figure 5. Transcription of a gene by the enzyme RNA polymerase and the subsequent translation of this messenger RNA ( mRNA ) 
by ribosomes to form a protein. 
From Raven, P.H., and Johnson, G.B. 1988. Understanding Biology. St. Louis, MO: Times Mirror /Mosby College Publishing, 
p. 267. 
EXTRACELLULAR 
SPACE 
apical plasma 
membrane 
transport 
vesicle 
Golgi 
apparatus 
transport 
vesicle 
membrane-bound 
polyribosomes 
in ER 
Figure 6. The synthesis and intracellular 
trafficking of proteins from the endoplas- 
mic reticulum through the Golgi apparatus 
to the cell membrane. 
From Alberts, B., Bray, D., Lewis, J., Raff, 
M., Roberts, K., and Watson, J. D. 1989. Mo- 
lecular Biology of the Cell, 2nd edition. New 
York: Garland, p. 455. 
basal plasma membrane 
