A peptide bond is formed via the condensation of one amino acid's alpha-carboxy group with the alpha-amino group of another amino acid. Thus, the joining together of two amino acids results in the loss of one water molecule. Likewise, joining three amino acids together results in the loss of two water molecules. Following this pattern, we can conclude that the number of water molecules lost is equal to the number of amino acids joined together, minus 1. Therefore, the joining together of 100 amino acids results in the loss of 99 water molecules.

A peptide bond connects two amino acids. This is the result of a condensation reaction (water is lost) and a new nitrogen-carbon bond forms between two amino acids. Note that amino acid synthesis occurs in the  direction. Peptide bonds are covalent bonds that are responsible for the primary structure of amino acids.

For this question, we are presented with three different amino acids and are asked how many possible ways they can be arranged. One way to do this is to list out all the various ways they can be connected.

1) Gly-Leu-Glu

2) Gly-Glu-Leu

3) Leu-Gly-Glu

4) Leu-Glu-Gly

5) Glu-Leu-Gly

6) Glu-Gly-Leu

Alternatively, we could use the mathematic expression  to determine the number of combinations of three separate things, which is equal to .

The peptide bond within a polypeptide creates planarity, while other parts of the polypeptide are free to rotate. This occurs because of a delocalization of the electrons on the nitrogen of the amino group (resonance), forming a partial double bond.

While there is a slight difference in electronegativity between carbon and nitrogen, this does not effect the planarity of a polypeptide. Additionally, while a small and insignificant amount of hydrogen bonding may occur between side chains and water, it would not effect planarity regardless.

A cis conformation is so rare due to steric clashes between side chains in different amino acid residues. The Van der Waals forces are simply to great for two side chains to occupy nearby spaces. However, proline is a very unique amino acid. Proline has a unique ring structure, in which its side chain is attached to its amino backbone group. Because of this, there is actually some steric clash in the trans conformation, in addition to the cis conformation. Overall, it is estimated that 10-30% of proline exists in the cis conformation, which is far greater than any other amino acid.

A Ramachandran plot, also referred to as a dihedral plot, tells us about what bond angles are favorable for an amino acid residue. The colored regions are favorable, while the uncolored (white) regions are not favorable. Additionally, each colored regions also corresponds to a different secondary structures (alpha helix, beta sheet, etc.).

These plots can't tell us much about the specific residue order within a polypeptide chain, or the energy required to break an amide bond.