Carrier proteins are the proteins present in the cell membrane which regulates the coming and going of substances into or out of the cell.
These carrier proteins can transport the molecules with the concentration gradient in the case of facilitated diffusion or can transport the molecules against the concentration gradient by using energy in the form of ATP in case of active transport.
Large, polar and charged molecules like amino acids, nucleosides, and ions are transported through carrier proteins. Binding of molecules to these proteins induce the conformational change in the proteins which allow the protein to be open from the opposite side to transport the molecule across the membrane.
In our bodies the hormones and other regulators that are present usually operate in small quantities that range from pico to microgram/ml of blood and this level of hormone and other regulators is referred to as the physiological level.
when treatments are given then it may lead to the production of these hormones or regulators that may exceed the physiological levels, and the levels may increase up to milligram range.
Such treatments levels that lead to the excess production fo circulating levels that surpass the natural or optimal levels are termed as pharmacological doses.
The correct answer is the G2 phase. The G2 phase is usually the shortest of the three phases pf interphase. During G2 phase, many of the organelles and molecules required for cell division are produced. When the G2 phase is completed, the cell is ready to enter Mitosis and begin cell division. Hopes this helps!
