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Macromolecules often have unusual physical properties. For example, individual pieces of DNA in a solution can be broken in two simply by sucking the solution through an ordinary straw. This is not true of smaller molecules. The 1964 edition of Linus Pauling's College Chemistry asserted that DNA in nature is never longer than about 5,000 base pairs. This error arose because biochemists were inadvertently and consistently breaking their samples into pieces. In fact, the DNA of chromosomes can be hundreds of millions of base pairs long.
Another common macromolecular property that does not characterize smaller molecules is their relative insolubility in water and similar solvents. Many require salts or particular ions to dissolve in water. Similarly, many proteins will denature if the solute concentration of their solution is too high or too low.
High concentrations of macromolecules in a solution can alter the rates and equilibrium constants of the reactions of other macromolecules, through an effect known as macromolecular crowding.[8] This comes from macromolecules excluding other molecules from a large part of the volume of the solution, thereby increasing the effective concentrations of these molecules.