The Che proteins (chemotaxis proteins) are cytoplasmic proteins that play an important role in signal transduction pathways between the repellent or attractant and flagellar motor switch of a bacterium. Bacterial cell membranes contain different chemoreceptors for different attractants and repellents.
When a repellent or attractant binds with a chemoreceptor, stimulation of signal-transduction pathway occurs. It sends a signal to the cytoplasmic domain of receptor, which interacts with Che proteins, present at cytoplasm. The rate of auto-phosphorylation decreases when an attractant binds with receptor, while the rate of auto-phosphorylation increases when an attractant binds with receptor.
Thus, 'the attractant enhances smooth swimming and counterclockwise rotation towards the chemical source, which repellent enhances tumbling clockwise rotation away from a chemical source.'
Fats must be broken down into fatty acids before being converted into glucose. Lipids are known as the back up energy source. They are used to make enzymes, hormones, and antibodies.