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Cytology

(k) They form plasma proteins, such 1.4.3 Proteins
as lipoproteins which facilitate
transportation of lipids in the aqueous Task 1.6
environment of the body. Search for information from the library
and internet sources and prepare a brief

Activity 1.6: Biochemical test for lipids report about:
FOR ONLINE READING ONLY
(a) properties of protein
Materials
Groundnuts, test tubes, test tube racks, (b) biochemical tests for protein then.
test tube brush, beaker, measuring
cylinder, droppers, mortar and pestle, Proteins are large biomolecules or
Sudan III solution and distilled water macromolecules, consisting of one or

Procedure more long chains of amino acids. A protein
(a) Prepare a solution from the nuts molecule contains carbon, hydrogen,
using the materials provided. oxygen, nitrogen, sulphur and sometimes

(b) Carry out a biochemical test to phosphorus. The amino group (NH )
2
identify food substance(s) present provides protein’s basic nature, and the
in the solution using the reagents carboxyl group (-COOH) gives the acidic
provided. nature of the amino acid. The R-group is

(c) Tabulate your results, showing known as the side chain which represents
the procedure, observation and the hydrogen atom or any other group such
inference. as the alkyl group (Figure 1.31). Proteins

differ from one another, primarily in their
Exercise 1.12 sequence of amino acids, which is dictated

1. Explain the properties of lipids. by the nucleotide sequence of their genes
2. Classify the lipids based on their and which usually results in protein folding
chemical composition. into specific three-dimension structure that

3. Describe the structural functions determines its activity.
of lipids in living organisms.

H H O

H N C C OH

Amino group Carboxylic acid group
R
Side chain
Figure 1.31: Structure of the amino acids

Form Five Student’s Book
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