Amino acids and proteins, Study Guides, Projects, Research of Biomedicine

Download Amino acids and proteins and more Study Guides, Projects, Research Biomedicine in PDF only on Docsity! REVIEW QUESTIONS QUESTION ONE 1. Compounds having the same structural formula but differing in spatial configuration are known as a) enantiomers b) anomers c) optical isomers d) epimers 2. The general formula of monosaccharides is a) CnH2nOn b) C2nH2On c) CnH2n O2n d) CnH2O2n 3. Isomers differing as a result of variations in configuration of the —OH and —H on carbon atoms 2, 3 and 4 of glucose are known as a) epimers b) optical isomers c) anomers d) stereoisomers 4. Homodisaccharides linked by α-(1-4)-glucosidic linkage is (a) lactose (b) maltose (c) sucrose (d) isomaltose 5. In glucose the orientation of the —H and —OH groups around the carbon atom 5 adjacent to the terminal primary alcohol carbon determines a) Epimers b) D or L series c) Anomers d) α and β anomers 6. α-D-glucose and β -D-glucose are a) Stereoisomers b) Anomers c) Epimers d) Keto-aldo pairs 7. Lactose is a disaccharide formed by the formation of a bond between glucose and ________. a) glycosidic; lactose b) glycosidic; galactose c) hydrogen; sucrose d) hydrogen; fructose 8. Amylose is a type of c) Carrier proteins can mediate active transport, while channel proteins cannot. d) Carrier proteins do not bind to the material transported, while channel proteins do. e) Carrier proteins are synthesized on free cytoplasmic ribosomes, while channel proteins are synthesized on ribosomes bound to the endoplasmic reticulum. 16. All of the following statements about the fluid mosaic model of biological membranes are true EXCEPT: a) Lipid molecules in the membrane readily undergo lateral diffusion. b) Lipid molecules in the membrane readily undergo transverse (flip-flop) diffusion. c) Integral membrane proteins can undergo lateral diffusion. d) The saturated hydrocarbon chains of lipid molecules in the membrane undergo carbon-carbon bond rotation. e) The transition temperature of a membrane is sensitive to the composition of the lipid molecules in the membrane. 17. What locks all transmembrane proteins in the bilayer? a) Chemical bonds that form between the phospholipids and the protein. b) Hydrophobic interactions between nonpolar amino acids of the proteins and the aqueous environments of the cell c) Attachment to the cytoskeleton d)The addition of sugar molecules to the protein surface facing the external environment True/False 1. Lipids yield more energy per gram than carohydrates 2. Fatty acid molecules are amphipathic by nature 3. Phosphatidic acid is the simplest glycerophospholipid while ceramide is the simplest sphingolipid QUESTION TWO 1. Use an aldose sugar structures to illustrate the following types of stereoisomers. (a) Enantiomer (b) Epimer (c) Distereoisomer 2. Study the following structure and answer the questions that follow 3. Determine the value of n in each of the following using the chemical structure above. (a) (CH2O) n (b) H [CH (OH)] n (c) 2n 4. Some people cannot digest the disaccharide lactose. The term for this is known as lactose intolerance. Lactose is shown below. Answer the following questions. a. Label anomeric carbons by circling them. Is lactose a reducing sugar? b. Draw an arrow pointing to the glycosidic bond. Is the glycosidic bond connected to both anomeric carbons? c. Classify the glycosidic bonds using the alpha or beta-(α or β) format. d. If the glycosidic bond is hydrolyzed, what are the names of the monosaccharides produced. Remember to include the alpha or beta classification for the anomeric carbon. 5. Maltose, sucrose and lactose are the three of examples are disaccharides. These sugars have no free anomeric carbon, because of the glycosidic bonding. What are the possible roles of an anomeric carbon(s)? 6. What are the common names of these sugars? (a) Glucose (b) Galactose (c) Fructose (d) Sucrose (e) Lactose (f) Maltose 19. Without using any structure for demonstration, what are the similarities and differences between cerebroside and ganglioside? 20. Why is animal membrane less fluidity and more rigid? 21. How do you distinguish the inner and outer lipid layers from each other? 22. Why the transmembrane proteins have alpha-helix/beta-sheet as the most common structural motif? 23. Study the following structures and answer question a; b and c as follow: a). Examine the following two fatty acids. Classify them in detail as cis or trans form. b). Which of the two would be more densely packed together? c). Which one would have the lower melting point? 24. Explain in detail as to what do you understand by looking at the figure below? A B 25. Why lateral motion is called a spontaneous process different from flip-flop motion? 26. Describe five functions of membrane proteins. 27. Both fatty acids and steroids (and steroid derivatives) such as cholesterol are part of the lipid family of biomolecules. In what way are fatty acids and cholesterol similar? 28. State and discuss three factors that affect membrane fluidity in detail. 29. Describe in principle, how transmembrane proteins are purified. 30. Suggest a reason why inorganic ions, such as K+, Na+, Ca2+ and Mg2+, do not cross the biological membranes by simple diffusion