Carrier proteins allow cells to acquire molecules (such as sodium) that are necessary for the cell to carry out its function. As the cell will often be heavily saturated with such molecules, a gradient across the membrane is set up which does not favour inward movement. Therefore, with the use of carrier proteins, substances can be actively transported against the concentration gradient from outside the cell to inside the cell.
Also, they work by inducing a reversible conformational change in protein structure when the molecule binds to the specific binding domain outside (or inside) of the cell. This reversible conformational change offers a passage for the molecule to the inside of the cell.
Okays so the carrier protein are just something which attach to the molecules and the energy will allow these to push through the protein to the other side of the membrane?
Furthermore, is respiration and aerobic respiration the same thing? So if it said respiration somewhere would it be talking about aerobic respiration?
And yeah as said respiration can be aerobic (requires oxygen) or anaerobic (does not require oxygen). When possible aerobic respiration will dominate as it yields more energy.