Fina Examination 16) For proteins to fold correctly, there can be free rotation

Question

Fina Examination 16) For proteins to fold correctly, there can be free rotation around theand bonds of the peptide chain. a) Phi c) Omega d) A and B e) Aand C 17) If you identified a protein secondary structure separated by a short 4 amino acid sequence containing a proline you might have an a) Antiparallel B-sheet b) Random co c) Parallel ?-sheet d) ?-helix e) Not enough information to determine the structure 18) An example of protein quaternary structure would be a) The amino acid sequence b) ?-helices c) A helix-turn-helix motif d) The 3-dimensional folded protien e) A homo-dimer of peptides 19) Which statement is not part of the description of the fluid mosaic model of membrane structure? a) Membranes are bilaminar and composed primarily of phospholipids b) Lipids can freely diffuse from one leaflet to the other leaflet c) Embedded proteins and lipids and can diffuse freely within the plane of the membrane d) Membranes exist in a viscous fluid state e) Proteins can be peripherally associated or embedded into membranes 20) Prostaglandin synthesis, and inflammation, can be inhibited by the action of the nonsteroidal anti-inflammatory drugs, aspirin and ibuprofen, competing with binding of to cyclooxygenases a) Thombroxanes b) Histamine c) Linolineic acid d) Sterols e) Arachidonic acid

Explanation / Answer

Ans 16: ( D ) A and B

( psi and phi) -- called torsion angles.

Ans 17. ( a ) antiparallel beta- sheet

Two anti parallel strands are linked by a short loop of two to five residues.

Ans 18: (e) A homo - dimer of peptides

Ans 19: ( d )

The fluidity and elasticity of membrane is due to lipid bilayer structure. The cell membrane consists of highly viscous fluid matrix of two layers of phospholipid molecules.

Ans 20: ( a )

Inflammation is reaction of living tissue to injury, irritation or infections. The injured region attract mast cells ( histaminocytes) of connective tissue and basophils of blood. They produce prostaglandin and histamins.

Histamin dilates blood capillaries and other small vessels. Therefore, more blood flows into the area of injury making it warm and red. Increased influx of phagocytes allows destruction of microorganisms. Plasma contains serum proteins with antimicrobial activity. Accumulation of these tissue fluid causes swelling.

Aspirin and ibuprofen ( NSAID ) inhibit the activity of prostaglandin and thromboxanes in which prostaglandins involved in inflammation and thromboxanes in blood clotting.

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