Exam in: Kje-2002 Molecular Structural Chemistry Date: Friday 29. November 2013 Time: Kl 15:00 19:00 Place: Åsgårdsveien 9

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1 EXAMINATION PAPER Exam in: Kje-2002 Molecular Structural Chemistry Date: Friday 29. November 2013 Time: Kl 15:00 19:00 Place: Åsgårdsveien 9 Approved aids: Calculator The exam contains 6 pages included this cover page Contact person: Ingar Leiros Phone: /

2 Question 1. Multiple choices. Select the correct answer to the statements. (Answer in a form like this: 1a), 2d), etc.) 1. The three-dimensional structure of macromolecules is formed and maintained primarily through noncovalent interactions. Which of the following is not considered a noncovalent interaction? a) hydrogen bonds b) van der Waals interactions c) disulfide bonds d) ion-pair interaction (salt bridges) 2. Which of the following amino acids is the smallest of all amino acids? a) Glycine b) Histidine c) Valine d) Lysine 3. In an α-helix, the R-groups on the amino acid residues. a) are found on the outside of the helix spiral b) generate the hydrogen bonds that form the helix c) stack the interior of the helix d) alternate between the outside and the inside of the helix 4. Peptide bonds link. a) fats b) amino acids c) nucleic acids d) carbohydrates 5. This stabilizes the secondary structure of proteins. a) peptide bonds b) psi bonds c) phi bonds d) hydrogen bonds 6. Amino acids that an organism cannot synthesize on its own are called a) essential amino acids b) basic amino acids c) acidic amino acids d) forced amino acids UiT / Postboks 6050 Langnes, N-9037 Tromsø / / postmottak@uit.no / uit.no 2

3 7. The amino acids sequence of a protein is the structure. a) primary b) secondary c) tertiary d) quaternary 8. Proteins are composed of monomer units. These units are called. a) peptide bonds b) functional groups c) amino acids d) thiols 9. The two strands of double-stranded DNA are interconnected by a) peptide bonds b) glycosidic bonds c) hydrogen bonds d) phosphodiester bonds 10. What is the main carbohydrate storage form in animals? a) cellulose b) protein c) starch d) glycogen 11. Of what is a triglyceride composed? a) One glycerol with 3 fatty acids b) 3 glycerides c) 3 glycerols and one fatty acid d) 3 fatty acids 12. In nucleic acids, the purine bases are. a) uracil and thymine b) cytosine and guanine c) thymine and cytosine d) adenine and guanine 13. What type of macromolecule carries out catalysis in biological systems? a) proteins called enzymes b) nucleic acids called DNA c) carbohydrates called sugars d) lipids called steroids UiT / Postboks 6050 Langnes, N-9037 Tromsø / / postmottak@uit.no / uit.no 3

4 14. Glucose is a. a) protein b) disaccharide c) nucleic acid d) monosaccharide 15. Which of the following bases is found in DNA but is not found in RNA? a) adenine b) cytosine c) thymine d) uracil 16. Fats and oils are composed of what two groups of molecules? a) starch and sugar b) glucose and fructose c) fatty acids and glycerol d) water and cellulose 17. Viruses possess genetic material composed of. a) protein only b) RNA only c) DNA and RNA together d) DNA or RNA 18. Viruses that infect bacteria are called. a) bacteriophages b) virions c) polyhedral d) hepadnaviridae UiT / Postboks 6050 Langnes, N-9037 Tromsø / / postmottak@uit.no / uit.no 4

5 Question 2. A Ramachandran plot is outlined: a) What angles are plotted along the x-axis and y-axis? Explain where these angles originate from. b) What do the framed areas in the Ramachandran plot represent? c) Which amino acids are generally not taken into account in the Ramachandran plot? Explain why. d) How can amino acids be classified with respect to properties? Give examples of such properties. e) What functions can proteins have? Describe briefly as many of these as possible. UiT / Postboks 6050 Langnes, N-9037 Tromsø / / postmottak@uit.no / uit.no 5

6 Question 3. a) Some important terms in Nuclear Magnetic Resonance (NMR) are: i) spin ii) spectrum iii) chemical shifts iv) internal standard. Explain briefly each of the terms. b) Deuteration is commonly used in Neutron Diffraction, but can also be used in Nuclear Magnetic Resonance (NMR). Describe briefly two main applications for deuteration when studying proteins with NMR. c) What is the difference between spin coupling and Nuclear Overhauser Effect (NOE)? Question 4. a) Give an overview of the most common method for crystallising macromolecules. b) Describe briefly the steps taken in order to solve the three-dimensional structure of a protein using X-ray crystallography. Assume that you are starting with a crystal. c) What is a big technical drawback of X-ray crystallography compared to NMR? Good luck! UiT / Postboks 6050 Langnes, N-9037 Tromsø / / postmottak@uit.no / uit.no 6