At $\mathrm{pH} 7$, a solution of alanine contains both the zwitterion and negatively charged (anionic) forms of alanine. Deduce the structural formula of each of these forms.$\mathrm{}$

State equations which show the buffer action of the alanine solution when a small amount of strong acid is added and a small amount of strong base is added.

An amino acid buffer has been prepared by mixing $0.60 {\mathrm{dm}}^3$ of $0.20 \mathrm{mol} {\mathrm{dm}}^3$ $\mathrm{HCl}$ and $0.40 {\mathrm{dm}}^3$ of $0.50 \mathrm{mol} {\mathrm{dm}}^3$ glycine solutions. Calculate the $\mathrm{pH}$ of the original buffer solution. 

Assume that the densities of all solutions are $1.0 \mathrm{kg} {\mathrm{dm}}^3$ and the volume of the buffer solution does not change when small amounts of strong acid or base are added.

An amino acid buffer has been prepared by mixing $0.60 {\mathrm{dm}}^3$ of $0.20 \mathrm{mol} {\mathrm{dm}}^3$ $\mathrm{HCl}$ and $0.40 {\mathrm{dm}}^3$ of $0.50 \mathrm{mol} {\mathrm{dm}}^3$ glycine solutions. Calculate the $\mathrm{pH}$ of the solution after the addition of $1.0 {\mathrm{cm}}^3$ of $1.0 \mathrm{mol} {\mathrm{dm}}^3 \mathrm{HCl}$

Assume that the densities of all solutions are $1.0 \mathrm{kg} {\mathrm{dm}}^3$ and the volume of the buffer solution does not change when small amounts of strong acid or base are added.

An amino acid buffer has been prepared by mixing $0.60 {\mathrm{dm}}^3$ of $0.20 \mathrm{mol} {\mathrm{dm}}^3$ $\mathrm{HCl}$ and $0.40 {\mathrm{dm}}^3$ of $0.50 \mathrm{mol} {\mathrm{dm}}^3$ glycine solutions. Calculate the $\mathrm{pH}$ of the solution after the addition of $0.40 \mathrm{g}$ of solid $\mathrm{NaOH}$

Assume that the densities of all solutions are $1.0 \mathrm{kg} {\mathrm{dm}}^3$ and the volume of the buffer solution does not change when small amounts of strong acid or base are added.

Compare the behaviour of enzymes and inorganic catalysts, including reference to the mechanism of enzyme action and the ways in which this can be inhibited.

The term “lock and key” is a simple and effective metaphor but the “induced fit” model provides a more comprehensive explanation of enzyme catalysis. Discuss how metaphors and models are used in the construction of our knowledge of the natural world.

Pepsin is an enzyme found in the stomach that speeds up the breakdown of proteins. Iron is used to speed up the production of ammonia in the Haber process. Describe the characteristics of an enzyme such as pepsin, and compare its catalytic behaviour to an inorganic catalyst such as iron.

Enzymes are affected by inhibitors. Lead ions are a non-competitive inhibitor; they have been linked to impaired mental functioning. Ritonavir® is a drug used to treat HIV and acts as a competitive inhibitor. Compare the action of lead ions and Ritonavir® on enzymes, and how they affect the initial rate of reaction of the enzyme with its substrate and the values of K_m and V_max.