Early in his presidency, Theodore Roosevelt sparked a scandal when he invited the African-American educator Booker T. Washington to dine with him and his family; he was the first president ever to entertain a black man in the White House. In 1886, Roosevelt ran unsuccessfully for mayor of New York City. Two years later, President Benjamin Harrison rewarded Rooseveltâs service to the Republican Party with a job on the U.S. Civil Service Commission; he was reappointed by Harrisonâs successor, Grover Cleveland.
1 Signaling involves a receptor, the transduction of information from the cell surface to inside the cell, and subcellular systems that make a response. 2  Receptors are proteins with specific binding sites for signaling molecules called ligands. All cells are equipped with elaborate systems for receiving signals from their environment. 2  The mechanisms involved in cell signaling are particularly crucial for understanding multi-cellular organisms, and are an important in many diseases.
The Cell Nucleus: The cell nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction. It is the command center of a eukaryotic cell and is commonly the most prominent organelle in a cell.he cell nucleus is bound by a double membrane called the nuclear envelope. This membrane separates the contents of the nucleus from the cytoplasm. Like the cell membrane, the nuclear envelope consists of phospholipids that form a lipid bilayer.