2.12. Assignments

1. Write down the structure of 22^nd natural amino acid, its 3 letter code and single letter code.
2. Write down any one structure, name, 3-letter code and one letter code of amino acid of each category: (a) Neutral amino acid with hydrophilic side chain, (b) Acidic Amino Acid and (c) basic amino acid.
3. Name the main three types of protein’s secondary structures. Write down the general structures of β³- and β²-amino acids.
4. What do you mean by genetic alphabet, genetic codon and genetic code?
5. Define the followings: (a) Chemical Biology, (b) Biochemistry, (c) Bio-organic Chemistry, (d) Proteomics and (e) Glycobiology
6. Answer the followings:
   1. If three different amino acids (gly, ala, leu) are used to make a tripeptide, how many different sequences are possible?
      1. 6
      2. 9
      3. 3
      4. 12
   2. The primary structures of methionine-enkephaline is: tyr - gly - gly - phe – met. The N-terminal and  the C-terminal amino acids respectively are:-
      1. met-  and gly-
      2. Tyr- and gly -
      3. tyr – and phe – 
      4. tyr - and met-
   3. Normal hemoglobin is apparently more polar and soluble in water because of the presence of polar amino acid glutamic acid but Sickle Cell hemoglobin is more non-polar and insoluble. The non-polar amino acid  present in Sickle Cell hemoglobin is-
      1. Isoleucine
      2. Leucine
      3. Valine
      4. Alanine
   4. The order of increasing polarity of the amino acids-Ser; Glu; Asp; Lys; Ala; Gln is
      1. Ser > Glu > Asp > Lys > Ala > Gln
      2. Ser > Glu > Asp > Lys > Gln > Ala
      3. Glu > Ser > Asp > Lys > Gln > Ala
      4. Ala < Lys < Ser < Glu < Asp < Gln
7. Explain the differences between primary, secondary, tertiary, and quaternary protein structures by giving brief definitions of each.  What types of bonding are used in each?
8. Explain the difference between the alpha helix and the beta pleated sheet protein structures.  What are the differences in the hydrogen bonding?
9. Write down the structure of A, B, C and the absolute configuration of the produced chiral aminoacid in the following scheme.
   

   

10. Why the solid phase peptide synthesis proceeds from C to N-terminus and not N to C terminus synthesis?
11. What are the main applications of unnatural amino acids?