Protein Function

Once again, this post is included mainly for completeness.

Know proteins bind other molecules and be able to give examples of these other molecules.

I think I've mentioned this before. This binding is why protein shape is so critical to its function- see my earlier post on levels of protein structure. As an example, antibodies bind to specific molecules called antigens, targeting them for destruction.
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Be able to give an example of fibrous and globular proteins.

Many structural proteins, such as keratin, are fibrous. I'm not sure what the exact definition of a fibrous protein is but the idea I'm getting is that they are long and ropelike, and can often wind around each other into coiled-coils for even greater stability.

Many enzymes are globular proteins. Globular proteins are more "folded up" and usually have their hydrophobic residues on the inside and hydrophilic residues on the outside. There is also a special "active site" which is where the ligand (another molecule) binds.

Know how enzymes are regulated and be able to give examples.

Enzymes are regulated through several different mechanisms. Their production can be regulated via regulation of gene expression. Degradation, too, can also be regulated. Enzymes can also be compartmentalised in different areas of the cell- for example, DNA endonuclease normally exists in the cytosol, but when it's time for the cell to die, it moves into the nucleus where it chops up the DNA. Another way in which enzymes can be regulated is through the binding of other molecules. Sometimes binding of other molecules alters the shape of an enzyme, which may change the shape of the active site, which in turn may affect the ability of the enzyme to carry out its function. (Proteins that are regulated like this are known as "allosteric.") Addition or removal of phosphate groups may also contribute to the regulation of enzymes.

Know how to interpret an evolutionary tree.

As there are evolutionary trees of organisms, there are also evolutionary trees of proteins which reflect the similarity of amino acid sequences. Proteins that cluster together are more similar to each other, whereas those that are further apart are less similar. Proteins that are similar in amino acid sequences also tend to be similar in function.

Know how motor proteins generate movement.

Motor proteins generate movement by changing their conformation, a process driven by ATP. Often ATP hydrolysis occurs at the head regions of these proteins, while the "cargo" that they move along is held on the tail regions of motor proteins.