Question

1) By mass, what is the most abundant element in proteins? What about by mole?

2) Which of the 20 amino acids is it not possible to draw both its L and D form?

3) Identify the amino acids with non-polar sidechains and those with side chains that are charged at pH = 7.0.

4) Lysine, Arginine and Histidine all bear a positive charge below pH 6.0. What is different about the positive charges on both Arginine and Histidine in comparison to Lysine?

5) The genetic code has a built in mechanism to protect from deleterious mutations that are likely to affect protein function. Provide an example?

Please ANSWER ALL QUESTIONS.

Answer 1

1. Carbon is the most abundant element in protien by mass, it is just the basic part of all organic substances. Even though nitrogen as the main component because protiens cant be formed without amine groups (NH2).

2. Glycine. Glycine is achiral because central carbon atom in glycine contains only 3 unique substituents instead of 4 so glycine can not show D and L form.

3. Five have a side chain which can be charged among the 20 common amino acids at pH=7, two are negative charged: aspartic acid (Asp, D) and glutamic acid (Glu, E) (have acidic side chains), and three are positive charged: lysine (Lys, K),arginine (Arg, R) and histidine (His, H) (have basic side chains).

4.In image

5. The genetic code is redundant in that the same amino acid residue can be encoded by multiple, so-called synonymous, codons. example- In case of silent substitution is a type of mutation, changes one codon for an amino acid into another codon for that same amino acid. eg. codon AAA is altered to become AAG, the same amino acid – lysine – will be incorporated into the peptide chain.