IGNOU CHE-09 - Biochemistry

1. a) Differentiate between glyoxisomes and peroxisomes and give their important functions. b) Describe the process of anomerisation taking glucose as the representative example. 2. a) Write five chemical reactions which justify the pentahydroxy structure of glucose. b) What are ketone bodies? How are these produced in the body? What does their presence in the body signify? 3. a) Name the different components of the cell membrane and state its functions. Who gave the fluid mosaic model of structure of cell membrane? b) What is the most common form of DNA? Explain the nature of forces responsible for holding the double helix together. 4. a) What is the role of hydrophobic interactions in protein folding. Differentiate between the tertiary and quaternary structures of proteins. b) What is meant by catalytic efficiency of an enzyme? Describe the mechanism of enzyme action. 5. a) What is the difference between vitamins and coenzymes? Why should our daily diet contain water soluble vitamins? Write the physiological functions of calcium, phosphorus, sodium and potassium. b) Differentiate between cysteine and cystine. What is the role of cystine in maintaining protein structure? 6. a) Describe and differentiate between substrate level phosphorylation and oxidative phosphorylation taking suitable examples for both. b) Name two inhibitors of glycolysis and explain their mechanism of action. 7. a) Explain the following with respect to TCA cycle: i) Substrate chanelling ii) Anaplerosis b) Describe the regulation of pyruvate dehydrogenase complex by product inhibition. 8. a) Define funelling effect, photosystem and photophosphorylation in photosynthesis. b) What is Hill reaction? Write the balanced equation for Hill reaction. Which photosystem is responsible for this? 9. a) Name one similarity and one dissimilarity between the action of DNA polymerase and RNA polymerase. Describe the transcription process. b) Describe the scope of biotechnology. Describe the process of separation of penicillin in the final stage of production. 10. a) Describe the activation of amino acids during protein biosynthesis. How does an antibiotic affect protein biosynthesis? b) List the different types of antibodies. What are the gross structural features of an antibody molecule? Name any three mechanisms by which antibodies interact with antigens.

1. a) What will be the sequence of separation of the organelles, ribosomes, nucleus and mitochondria in a tissue homogenate when subjected to centrifugation. Explain your answer. b) How are peroxisomes and lysosomes generated in a cell? c) Briefly describe different modes through which cell membrane controls the transport of ingoing and outgoing molecules? 2. a) What are reducing sugars? Sucrose is made up of two reducing sugars however it does not show the property of a reducing sugar. Explain. b) A fat has low iodine number and a high saponification number. What do you infer form that? What are essential fatty acids and why are they essential? 3. a) Draw the structure of a dinucleotide of adenosine – 5’- phosphate and uridine- 5’- phosphate. b) In which process of protein biosynthesis, t-RNA is involved? Illustrate the gross structural features of t-RNA. Indicate the different regions. c) Write a short note on the different forms of DNA. 4. a) Briefly describe the four ways by which enzymes can lower the activation energy. b) What is optimal pH? How can a change in pH render an enzyme inactive? 5. a) Name the vitamin whose coenzyme is unknown. What is the importance of this enzyme in our diet? b) Why is calcitriol classified as a hormone? c) What is the difference between macrominerals and trace elements? Write the main functions of any four trace elements? 6. a) How is the standard free energy for chemical reactions different form the standard free energy for biochemical reactions? b) Find out the value of free energy for a reaction when Keq is 1.0 and for another reaction where Keq is 10. c) With the help of an example explain the significance of coupling in biological reactions. 7. a) Standard free energy change alone cannot predict the direction of a biochemical reaction. Comment b) Enlist all the enzymes involved in glycolysis and write the type of reaction they catalyse. 8. a) What is meant by respiratory control? How is the rate of flow of electrons through the electron transport chain regulated? b) Why are chlorophyll molecules coloured? What are the other types of light absorbing substances in plants and how they are significant? 9. a) Compare the function of RNA polymerase with DNA polymerase. How is transcription terminated? b) What are the components of the initiation complex during protein biosynthesis in E.coli? How does the elongation of chain take place? 10. a) What is genetic engineering? Discuss its significance to mankind. b) List different types of antibodies. What are the gross structural features of antibody molecules? Discuss any one mechanism by which antibodies interact with antigens.