Proteins

Question 1

Explain how a change in the primary structure of a globular protein may result in a different three-dimensional structure.

Answer 1

sequence of amino acids changes;

so different bonds form

between R groups in different places

so the tertiary structure changes/folds in a different way;

Question 2

Describe the structure of proteins

Answer 2

A protein is a polymer of amino acids;

Joined by peptide bonds;

Formed by condensation;

Primary structure is order/sequence of amino acids;

Secondary structure is folding of polypeptide chain due to hydrogen bonding;

Tertiary structure is 3-D folding due to hydrogen bonding and ionic / disulfide bonds;

Quaternary structure is two or more polypeptide chains;

Question 3

Describe how you would use colorimetry to identify the concentration of glucose in an unknown solution

Answer 3

Carry out the Benedict’s test on samples of glucose with a known concentration of
glucose

Use a colorimeter to find the % light transmission of known samples of glucose

Draw a graph with glucose concentration on the x-axis and % light transmission on
the y-axis

Plot the points on the graph and draw a calibration curve

Carry out the Benedict’s test on the solution of glucose with an unknown
concentration

Find the % light transmission for this sample using the colorimeter

Find this % of light transmission on the y-axis and draw a horizontal line until you
reach the calibration curve. Then draw a vertical line down and read the conc. of
glucose from the x-axis.