Different types of peanuts. Not every peanut is the same! There are thousands of different types of peanuts, these are known as different cultivars. We can distinguish four popular different types of peanuts: the Runner peanut, the Virginia peanut, the Valencia peanut and the Spanish peanut. All these peanuts differ in size, color, flavor and oil content and are often used for very different purposes.
For a signal molecule to bind with an intracellular receptor it must be able to pass through the cellular membrane. Generally signal molecules that enter the cell are nonpolar and fat soluble. These signal molecules can pass through the lipid bilayer of the cell membrane.
Nonsteroid hormones, in general, cannot diffuse across the plasma membrane and therefore must interact with membrane receptors . Receptors of this type are usually transmembrane proteins that contain a hormone-binding domain outside of the cell and another domain inside of the cell that changes its shape when the hormone is bound. It subsequently causes other changes in the cell, usually by activating enzymes through a chemical intermediary. Since the hormone is not causing the changes directly, the intermediary is often referred to as a second messenger (the hormone being the âfirst messengerâ).