In order to determine the presence of peptide bonds in a protein you can use the biuret test. Biuret reagent, which is blue in colour, is added to a sample and left to stand for five minutes.

• If the sample changes from blue to purple then proteins are present.
• If the sample changes from blue to pink then peptides are present.
• ?-glucose
• The structure of ?-glucose is:?-glucose molecules link together by glycosidic bonds which are produced by condensation. Two ?-glucose molecules bonded together is called a disaccharide.

Active Transport

Active transport involves the movement of a solute across a semi-permeable membrane against their concentration gradient in other words: from an area of low concentration to an area of high concentration.

Active transport uses trans-membrane protein pumps which are highly specific to the molecule they’ll pump across the membrane. When a molecule binds to the protein, the protein changes shape and release the molecule onto the other side. It’s called active transport because the process requires energy (ATP) to work.

ATP is used in two ways during active transport:

• directly to move the molecules which is known as direct active transport
• by using a concentration gradient which has already been established by direct active transport, a process known as co-transport