Serous membranes line the mouth. have parietal and visceral layers. consist of epidermis and dermis. have a connective tissue layer called the lamina propria. secrete a lubricating fluid.

Ascientist introduced mutations in a gene sequence isolated from bacteria. study the sequence, and identify the steps where the mutations may affect the formation of proteins. in the sequence, black letters stand for protein coding regions and red letters stand for noncoding regions.