Question

40. This amino acid is not commonly found in a b-pleat. A) Alanine B) Tryptophan C) Leucine D) Valine E) Isoleucine

47. These amino acids would contribute to forming bridge salts in protein secondary and tertiary structures: A) Arginine, Lysine, Glutamic Acid, Aspartic Acid B) Methionine, C) Serine, Threonine D) Tryptophan, Tyrosine, Phenylalanine E) None of the above

24. The structure and general chemical composition of the cell membrane is similar to the membranes of organelles. True or false?

28. When bound to certain atoms, hydrogen can form a special type of bond. The following is correct regarding hydrogen bonds: A) In order to form a hydrogen bond, H must be bound to a more electronegative element such as O or N.

B) Hydrogen bonds are non-covalent.

C) Hydrogen bonds are weaker but numerous so they contribute to stabilize the structure of molecules such as proteins.

D) All of the above. E) None of the above.

14. This is an advantage for prokaryotic cells to have polycistronic mRNAs: A) Enzymes involved in entire metabolic pathways are encoded in a single message. B) All proteins in a polycistronic mRNA can be translated simultaneously. C) Faster adaptation to the environment when compared to eukaryotic organisms. D) Protein synthesis (translation) can occur while RNA synthesis (transcription) is still happening E) All of the above

Answer 1

40. Tryptophan is not found in b-pleat commonly. Due to it's bulky R group it doesn't fit in the groove, no hydrogen bond is formed.

47. Aspartic acid , glutamic Acid , lysine, arginine contribute to form salt bridge as these opositely charged residues can form an electrostatic interaction.

24. The structure and general chemical composition of cell membrane is topologically similar with inner phase of organelles. When organelles fused with plasma membrane, inside of organelles comes outside and attach with the cell membrane.

28. All the options are true.Hydrogen bond is always formed between two electonegative atoms where one atom acts as a hydrogen donar and another acts as a hydrogen acceptor. The energy of hydrogen bond is 5-10 kcal/mole that is less than 80 kcal/ mole so called non covalent interaction.