- A receptor protein is a protein molecule that receives chemical signals from outside a cell. When such chemical signals bind to a receptor, they cause some form of cellular/tissue response, e.g. a change in the electrical activity of a cell.
-They are generally trans-membrane proteins, which bind to signaling molecules outside the cell and subsequently transmit the signal through a sequence of molecular switches to internal signaling pathways. There are two types of receptors: internal receptors and cell-surface receptors.
Limiting factors determine carrying capacity. The availability of abiotic factors and biotic factors dictates how many organisms can live in an ecosystem. Carrying capacity is also impacted by the availability of decomposers. ... Humans can also alter carrying capacity.