Student activity AB2.14.1
Book links: Page 122
Specification links: B2.5.1 a–b
Lesson reference: B2.14 Proteins
Proteins
Equipment required per student/group:
Five test tubes and a test tube rack
White tile
Labels
Dropping pipette
Dilute sodium hydroxide solution
Dilute copper sulfate solution
Raw egg white suspension
Access to water bath set at 90 °C
70% ethanol (highly flammable)
1 mol dm-3 HCl
Timer
Cooked and raw chicken
A3 paper
Poster pens
Access to the Internet
Biology textbooks
Eye protection
Health and Safety notes:
 You must wear eye protection.
 Wash your hands with soap and water after handling raw chicken.
Getting started
In this experiment you will be finding out more about proteins.
Investigating
Investigating egg white protein
1 Collect five test tubes and stand them in a rack. Label them A–E.
2 Place 2 cm depth of raw egg white suspension into each of the tubes.
3 Perform tests on the egg white suspension as follows:
Tube A Leave untreated.
Tube B Place into the water bath at 90 °C. Observe after five minutes.
Tube C Carry out the Biuret test.to confirm that egg white is protein. Add a
few drops of dilute sodium hydroxide solution, followed by a few
Practical activities have been checked for health and safety advice by CLEAPSS.
All users will need to review the risk assessment information and may need to adapt it to local circumstances.
© Oxford University Press 2011
This document may have been altered from the original.
395
drops of dilute copper sulfate solution. A violet/mauve colour
indicates protein.
Tube D Add 1 mol dm-3 HCl, using a dropper pipette. Observe what happens
to the egg white protein.
Tube E Add a drop of 70% ethanol using a dropper pipette. Observe what
happens to the egg white protein.
Comparing cooked and uncooked meat
1 Observe the cooked chicken muscle and compare it to uncooked chicken
muscle. The heat has denatured its proteins.
2 Carry out a Biuret test on both the raw and cooked chicken meat, using the
same method that you used to test the egg white in tube C of Investigating egg
white protein.
3 You should observe that both raw and cooked chicken contains proteins. The
heat has denatured the muscle proteins of the cooked meat and changed their
shape, but they are still proteins.
Asking questions
Investigating egg white protein
A Observe tube 2. The egg white protein (albumen) has been denatured by the
heat. Describe how its appearance has changed.
B Observe tubes 4 and 5. Do you think that acids and ethanol denature this
protein?
Spreading the word
 Design and make a poster to inform members of the general public about the
importance of proteins.
 Decide who you are aiming your poster at, for example primary school
children, student nurses, or mothers of babies.
 You need to explain
 what proteins are – what are they made from and what types of molecule
they are
 where they are made
 why they are important – some examples of proteins in the body and what
they do.
 Use your Student book, other biology textbooks, and websites to obtain
information.
 The following websites may be useful:
 www.kidshealth.org, click on ‘Kids site’ and search for ‘learning about
proteins’.
 www.wisc-online.com, and search for ‘biomolecules the proteins’.
 www.chem4kids.com and search for ‘proteins’.
Practical activities have been checked for health and safety advice by CLEAPSS.
All users will need to review the risk assessment information and may need to adapt it to local circumstances.
© Oxford University Press 2011
This document may have been altered from the original.
396
Extension
Guess what I am
1 Work in pairs or small groups.
2 Write down a description of the structure, features, and function of a particular
protein.
3 Read this out to the rest of the class, but do not tell them the name of the
protein. They have to guess what protein you are describing.
Practical activities have been checked for health and safety advice by CLEAPSS.
All users will need to review the risk assessment information and may need to adapt it to local circumstances.
© Oxford University Press 2011
This document may have been altered from the original.
397