Name the two most common atoms hydrogen bonds within biological systems that give hydrogen a partial positive charge. 2. Are the atoms named in the question above in the backbone of the protein or are they found in R groups?  Which R groups? 3. Besides hydrogen, what other atom is involved in the hydrogen bonds in an alpha helix or beta sheet? In other words, hydrogen is interacting with what other atoms when it makes a hydrogen bond? 4. Write out, in order, the full names of the seven amino acids circled in the picture.

1. Proteins perform critical functions in all of our cells. Without proteins, life wouldn’t exist. Think of some specific proteins and describe what function they perform.  2. Explain the difference between secondary and tertiary protein structures. 3. How many water molecules are produced when a dipeptide is synthesized?

3. The following structures are the components of nucleic acid. CH2OH ОН NH2 ОН ОН A (a) Which type of base is the molecule B? (b) Is molecule A be found in DNA or RNA? Explain. (c) Draw a nucleoside using the appropriate structures provided above. While drawing the structure, also consider the conformation. 7 (d)What are the differences between the structure of dATP from the structure vou draw in (c)? (e) Fill in the blanks for the relative percentage of bases in a DNA. А G T 13 15 Strand 1 12 Strand 2

4. Let’s build a polypeptide chain a. Using your arsenal of 4 amino acids, write out the primary structure of an 8 amino acid long polypeptide that you might be called amphipathic and thus allow it to form a micelle in aqueous solution, identify amino acid 1 through 8 as well as the location of the amino and carboxy termini of the polypeptide. b. Explain why this polypeptide would be considered amphipathic and draw what the micelle might look like in water. c. Taking amino acids 3, 4, and 5, draw the molecular structure of this particular stretch of polypeptide chain. Along the backbone linkage of the polypeptide identify the peptide bonds with a PB, the bonds with free rotation FR, and bonds with limited rotation LR.