Question

1. How many different erent groups comprise the common amino acids (ie those incorporated into most groups comprise the com proteins)? A 2 B 10 C. 20 D 25 2. When two separate cysteine A. a sulfu r ate cysteine SH groups form a bridge with each other, SS, the bridge is called SH B. a disulfide link. C. a disulfur bridge. D. a sulfate link The pH at which a witterion has exactly a zero charge is called the A. isotonic point B, isoelectronie point. C. isometrie point. D. isoelectric point. 4. If the R group for the amino acid lysine is CH-CH-CH:CH-NH', then how many dissociable groups does lysine have in an acid-base titration? A B 2 C3 D. 4 3. Which of the following statements about the peptide bond is true? he peptide bond results from covalently linking the c-amino group of one amino acid with the o-carb group of another. B. The reaction that forms the peptide bond is a dehydration (ie, water is formed). C The peptide bond can also be called an amide bond. D. All of these statements about the peptide bond are true.

Answer 1

Ans- R group makes each amino acid different from the other. 20 R groups use to make protein.the correct option is C 20

ans2- disulfide link between thiol (SH) group of two cysteine residue So the option B disulfide link is the right answer

Ans3- at isoelectric point amino acid carries no net electric charge so option B isoelectric point Is the correct answer

ans4- R group of lysine contains only 1 dissociable group NH₃⁺ so option A is the right answer

ans5- peptide bond or amide bond is a type of covalent bond. peptide bond form when an alpha-amino group of one amino acid reacts with a carboxyl group of another amino acid and a water molecule also formed or release.

so option D all of these statement about the peptide bond are true is the right answer