Select the characteristic that is common to the structures of α-helices and β-sheets.

Cysteine’s side chain thiol is ionizable, where image005601c63e5.gif  and the R represents the rest of the amino acid molecule. Given the pH titration curve of the Cys side chain determine its ionization state at physiological pH (7.4).CyspKa.png

Identify the amino acid that will have a net charge of +1 at pH 7.

The image below is a stick rendering of an α-helix looking end-on from its N-terminus. What occupies the interior space of the helix center (arrow) in proteins? AlphaHelix_N_color.png      

Click on the oxygen atom of the depicted dipeptide that is incorrectly displayed at physiological pH (pH 7.4).

The side chain of which amino acid below is most likely to be buried in the hydrophobic core of a protein? HSLKP.png 

Given the progress curve below for the uncatalyzed reaction L-Pro ↔ D-Pro, identify the correct response to each prompt. AxSA6c.png

 What is the relationship between temperature and heat?

How does a bimetallic strip work in thermostats?

What is the difference between atoms and molecules? How do compounds and elements differ?