ABSTRACT
As depicted in Fig. 2.1 (see also Color Plate 1), the numerous internal components of a cell each serve a particular function. These structures include the cell membrane, nucleus, ribosomes, endoplasmic reticulum, mitochondria, golgi complex, microtubules, and synaptic vesicles as well as other structures. The cell body is encased in a semipermeable membrane consisting of a double layer of lipid molecules. Embedded in the membrane are proteins that have a number of functions and serve an essential role in communication between neurons. The intracellular space of the cell is filled with cytoplasm; within the cytoplasm is the nucleus of the cell containing the chromosomes and nucleolus. Chromosomes consist of strands of DNA, and portions of the DNA-the genes-initiate production of messenger ribonucleic acid (mRNA). The nucleolus produces ribosomes, and ribosomes interact with the mRNA to synthesize proteins for the cell. The endoplasmic reticulum is of two forms, rough and smooth. Rough endoplasmic reticulum contains ribosomes that produce proteins to be transported within and out of the cell. The smooth endoplasmic reticulum plays an important role in the production of lipids. The cell’s energy supply is produced by mitochondria. Mitochondria produce adenosine triphosphate (ATP), which the cell uses as an energy source. The main function of the golgi complex (or apparatus) is to assemble proteins and package molecules in vesicles such as neurotransmitters.
