Biochemistry Answers

Explain why enzyme are classified as catalysts.

Define a peptide bond.

Define pKa.

Describe how biomolecules can act as weak acids or bases.

Describe the different types of noncovalent bonds that are important
in stabilising biomolecules.

What must you do to make a 10 mM solution of NaOH when you are given a stock of NaOH that is 1 mM?

What is the pH of a mixture of 5 ml of 0.1 mol/litre sodium acetate and 4 ml of 0.1 mol/litre acetic acid? (pKa of acetic acid at 25oC = 4.76). How is the pH changed on adding 1 ml of 0.1 mol/litre HCl to the above mixture? (Show your answer by means of calculation)

You need to conduct an experiment in the laboratory. This requires that you prepare 500 ml of 0.5 M sodium acetate buffer with pH = 4.30. In laboratory you have 10 M solution of CH3COOH (pKa = 4.75), and a stock of CH3COONa.3H2O (MW=136.082 g/mol). Using the Henderson-Hasselbach equation and the mass balance and the ionization equation below, calculate how to prepare this buffer.
Assume that the preparation consists of weighing out the necessary amounts of the compounds, or pipetting the required volume of the stock solution available. These are subsequently dissolved in water, and the buffer is prepared in a volumetric flask. (8)
CH3COOH +H2O CH3COO- + H30
+

What must you do to make a 10 mM solution of NaOH when you are given a stock of NaOH that is 1 MM ?

Glucose is the major energy yielding nutrient for most cells. Assuming a cellular concentration of 1 mM, calculate how many molecules of glucose would be present in our hypothetical (& spherical) eukaryotic cell of size 50 micrometer.