1 Transformation: bacteria simply absorb, across their cell membrane and cell wall, DNA that is floating around in the environment. 2  Conjugation: bacteria directly transfer DNA from one bacterium to another through structures called pilli. Transformation: bacteria simply absorb, across their cell membrane and cell wall, DNA that is floating around in the environment. 2  Conjugation: bacteria directly transfer DNA from one bacterium to another through structures called pilli.
Food begins its journey through the digestive system in the mouth, before being pushed by a series of involuntary muscle contractions through the esophagus, then the stomach, and then the small and large intestines.
If the mouth is the gateway to the body, then the esophagus is a highway for food and drink to travel along to make it to the stomach. This body part has a very simple function, but can have many disorders. The esophagus is a tube that connects the throat (pharynx) and the stomach. It is about 8 inches (20 centimeters) long. The esophagus isnât just a hollow tube that food slips down like a water slide, though. The esophagus is made of muscles that contract to move food to the stomach.