What is ‘denaturing a protein’?

Denature: To change the natural qualities of something by chemical or physical means.

Protein: Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism. They are essential in the diet of animals for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes. *

Why are we learning about denaturing a protein???

Performance Task Review *• What is our performance task for this unit on

transformations?• What do you think the type of transformation

is for denaturing? (Hint: what are the transformations we have learned about?)

• Why is this a ____________ reaction? (Hint: what are the characteristics of this type of reaction? Look at the table in your notes!) **

Video on Denaturing a Protein

• Some words and ideas you will need to know:– What are amino acids? – What is protein structure?– Why do we denature a protein?– What is coagulation? Can you give an example?

What are amino acids?Any of a large number of compounds found in living cells that contain carbon, oxygen, hydrogen, and nitrogen, and join together to form proteins. Twenty of the naturally occurring amino acids are the building blocks of proteins, which they form by being connected to each other in chains. Eight of those twenty, called essential amino acids, cannot be synthesized in the cells of humans and must be consumed as part of the diet. The remaining twelve are nonessential amino acids.

What is protein structure?

Coagulation

• To change or be changed from a liquid into a thickened mass: egg white coagulating when heated; blood clotting over the wound; gravy congealing as it cools; milk that had curdled; used pectin to jell the jam.

• From the FreeOnlineDictionary.com

Draw a graphic organizer like this:

What is ‘denaturing a protein’?

Who is it?

What is happening?

Where does it happen?

Why do we need to do it?

How does it happen ?

Now we are ready to watch the video!

• http://www.youtube.com/watch?v=3IL_Df5ouUc (4 min)

• Watch first without taking notes, then we will watch again and take notes.

Another short video!

• http://www.youtube.com/watch?v=o2ju5ys3Cxc (35 sec egg)

Denaturing proteins experiment

• Initial observations and predictions (what do you expect to happen – make a hypothesis and describe the set up of your experiment – what are you going to do)

• Add hydrogen peroxide to fresh liver & make observations.

• Do same for cooked liver. • Describe and Compare your

observations.• Analysis: Explain if denaturation of the

protein in liver occurred and if so, how do you know?

BONUS!

• What is the temperature at which denaturation occurs (from video clip)?

• Is denaturation reversible?• What is happening when we heat a protein

and how is this similar to the experiment we did on phase change of water? How is it different?

Sources

• http://www.thefoodadvicecentre.co.uk/reference/protein/

• www.thefreedictionary.com• http://www.elmhurst.edu/~chm/

vchembook/568denaturation.html