Molecules of Life — DU B. Sc. (Hons) Biochemistry Previous Year Question Papers

There are six questions. (a) Define the following terms with suitable examples wherever applicable: (17) Isoelectric point (b) Match the biomolecules from List A with List B : List A : Glyceraldehyde, Palmitic acid, Phospholipid, Linoleic acid, Reducing sugar, Adenine, Cholesterol, Cerebroside, Ribose, List B : Pentose, Homopolysaccharide, Fructose, Triose, PUFA, Steroid, Glycolipid, Fatty acid, Nitrogenous base, Differentiate between the following : (a) Essential and non-essential amino acids (b) Reducing and non-reducing disaccharide (d) Cellulose and Glycogen (a) Draw the structure of the following : (b) Explain the salient features of the structure of B-DNA using a suitable diagram. (c) What are non-standard amino acids ? Discuss with suitable examples (any two). Draw the structures and mention their significance. 5x3 4. (a) Name the amino acid that absorb ultraviolet light. Which of these absorbs maximum UV light ? (b) Explain the effect of unsaturation on the melting point of fatty acids using suitable examples. (c) Indicate whether the following pairs of sugars are epimers, anomers or enantiomers : (i) D-Glucose and D-Mannose, and (iii) D-Fructose and L-Fructose. (d) Write an example each for the following : Essential fatty acid, an imino acid, a purine base, a sphingolipid, an amino acid that is optically inactive, a tetrameric protein. (e) Write briefly on the organization of DNA into Chromatin. 3x5 Mention the reasons for the following statements : (a) Amino acids act as buffers. (b) Lactose exists in two anomeric forms, while no anomeric form of sucrose has been reported. (c) DNA is more stable than RNA. (d) DNA rich in GC base pairs melts at a higher temperature than the DNA that is rich in AT base pairs. (e) Protein which is abundant in basic amino acids exhibits a positive charge. 3×5 (a) Write a note explaining the levels of protein structure. (b) Explain the functions of RNA briefly. (c) Why are triglycerides considered as preferred choice as storage fuel compared to Glycogen ? (d) What are Coenzymes ? Name any three Vitamins and their corresponding coenzymes. 5,4,3,3