7.5+Proteins

7 Nucleic acids and proteins - 7.1 DNA structure - 7.2 DNA replication - 7.3 Transcription - 7.4 Translation - 7.5 Proteins - 7.6 Enzymes

7.5 Proteins

 * Assessment statements** (IBO notes added to some points to clearly indicate what needs to be understood and what does not)
 * 7.5.1 || Explain the four levels of protein structure, indicating the significance of each level. Quaternary structure may involve the binding of a prosthetic group to form a conjugated protein. ||
 * 7.5.2 || Outline the difference between fibrous and globular proteins, with reference to two examples of each protein type. ||
 * 7.5.3 || Explain the significance of polar and non-polar amino acids. Limit this to controlling the position of proteins in membranes, creating hydrophilic channels through membranes, and the specificity of active sites in enzymes. ||
 * 7.5.4 || State four functions of proteins, giving a named example of each. Membrane proteins should not be included. ||

An alternative set of notes from [|i-Biology] can be found here media type="custom" key="23840122"
 * Workbooks and Worksheets **

Steven Taylor ( [|i-Biology] ) has a great presentation to view and take notes from before starting your notebook media type="custom" key="23840126"
 * Presentations and tutorials **

Biotopics has useful information and animations on [|protein structure]. Though you need only be able to give name examples for each of the different levels of protein structure for those that are interested can look at the details of the structure of [|insulin], [|haemoglobin and myoglobin].

Use teaching and visualization animations from St Olaf:
 * Different levels of protein structure and how they relate
 * How hydrophobic forces cause protein folding

Use [|click4biology] to review and complete your notes

__Build your own polypeptide__ Use this link, read the [|webpage] and the instructions. Additional instructions can be found below:
 * Activities**


 * Twist the wire to make their own six- to eight-amino acid polypeptide chain.
 * Leaving three finger-widths of space between each side chain.
 * There should be more hydrophobic side chains than charged side chains, but try to include at least one anionic and one cationic side chain

You've now constructed a short polypeptide. Consider the following questions then fold your polypeptide in response:
 * What you would expect the hydrophobic side chains to do when surrounded by water?
 * What would the anionic and cationic side chains would do?

You should now have a 3D, polypeptide. What is holding the structure in place?

Lastly you are going to simulate excessive heating. Shake your polypeptide - what happens?

Some of the hydrophobic side chains should be exposed. Because of their hydrophobic nature they are attracted to the hydrophobic regions on other similarly denatured proteins, simulate this by joining polypeptides. This aggregation simulates what can happen in cooking, e.g. cooking eggs.

//(ref: [] - structure of the activity largely based upon this article)//

[|Protein denaturation] is talked about in great detail here, non-chemistry students may find this challenging
 * Useful Links **