Chapter 2: Biological molecules
Exercise 2.4 Processing and analysing data You will need to be able to apply your factual knowledge in order to interpret unfamiliar data. Do not be put off by the fact that you have not seen the information in that context before – look carefully at the information and use your knowledge. 1 Look carefully at the fatty acids in Figure 2.2 and answer the questions. O OH O OH
H3C
Lauric acid
Linoleic acid
O OH O
OH
H3C
Oleic acid
Arachidonic acid
Figure 2.2 The structure of four different fatty acids.
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a Copy out and complete the table below identifying which fatty acids are saturated, monounsaturated and polyunsaturated.
Fatty acid
Type of fatty acid
Melting point / °C
lauric acid oleic acid linoleic acid arachidonic acid b The melting points of these fatty acids are: 45 °C, 13 °C, −49 °C, −11 °C. The presence of C=C bonds causes the melting point of fatty acids to be lowered. Match each fatty each with its corresponding melting point and enter the data in the table. c Suggest why the melting points of the different fatty acids are different.