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5. When charged amino acids are found in the otherwise hydrophobic core of proteins, they are usually found in pairs. Predict and describe the nature of this amino acid pair and give an explanation for this observation (that is, why they typically occur in pairs). 6. The hydrophobic effect mainly occurs because of: b. hydrogen bonding c. Van der Waals forces d. Entropy c. covalent bonding 7. Draw all of the ionic species of arginine beginning with the fully protonated species and ending with the fully deprotonated species arranging each ionic species from that which would appear at very low pH (such as, pH 1.0) to very high pH (such as pH14.0 ). Indicate the net charge for each ionic species. Calculate the pI (isoelectric point) for arginine. Refer to the pKa values provided on Table 2.1 at the end of this assignment. pI (isoelectric point =(pKa2+pKa3)/2=