Introduction

Proteins are large molecules containing carbon, hydrogen, oxygen and nitrogen atoms. They are built from small molecules called amino acids. Proteins are used to build structures within cells and organisms, they help fight diseases in the form of antibodies and form enzymes which enable essential chemical reactions to occur in cells.

Reading

Read and make notes on page 36.

Tasks

Add any unfamiliar key words to your key word glossary file and or the Quizlett App.

Summarise the uses of proteins in organisms in the form of a table.

Proteins are tested for using the Biuret test. Watch the video in the links below to find out about the Biuret test.

Write a brief summary of how the Biuret test is carried out.

Link

WATCH - Biuret Test Just in 3 Minutes (YouTube)

WATCH - Food Tests – GCSE Science Biology Required Practical (YouTube)

WATCH - Amoeba Sisters: Biomolecules (YouTube)

Download

READ - Food Types, Deficiencies and Food Tests (PowerPoint)

Tip: you will need to be able to describe and explain these biochemical tests: Iodine test (starch), Benedict’s test (reducing sugars), Biuret test (protein) and Ethanol Emulsion test (fats).

Review

Copy and complete the summary table below listing the names of the different food tests, the biological molecules that are being tested for and what a positive result looks like. The table has been started for you:

Foot test summary table
Name of Food Test	Biological Molecule being Tested For	Description of Positive Test Result
Iodine		Blue/black staining
Benedict's test
	Protein
	Fats